Urban forests in the global context

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FORESTS AND
SUSTAINABLE
CITIES
An internat ional journal of fore stry and forest ind ustries Vol. 69 2018/1
250
ISSN 0041-6436

World Forum on Urban Forests
Mantova, Italy, 28 November–1 December 2018 2018
The rst World Forum on Urban Forests will showcase cities
worldwide that are using urban forestry to provide economic
benets and ecosystem services and to strengthen social cohesion
and public involvement. The Forum will bring together actors from
around the world and across sectors to explore urban forestry
strategies towards a greener, healthier and happier future.
An initiative of FAO, the City of Mantova, the Italian Society of Silviculture and
Forest Ecology, and Politecnico di Milano
More information: www.wfuf2018.com
© BLUEJAYPHOTO
Mantova, Italy, will host the rst World Forum
on Urban Forests in November/December 2018

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ISBN 978-92-5-130383-2
Contents
Editorial 2
S. Borelli, M. Conigliaro and F. Pineda
Urban forests in the global context 3
P. Calaza, P. Cariñanos, F.J. Escobedo, J. Schwab and G. Tovar
Building green infrastructure and urban landscapes 11
C. Dobbs, A.A. Eleuterio, J.D. Amaya, J. Montoya and D. Kendal
The benets of urban and peri-urban forestry 22
D. J. Nowa k
Improving city forests through assessment, modelling
and monitoring 30
C.C. Konijnendijk, P. Rodbell, F. Salbitano, K. Sayers,
S. Jiménez Villarpando and M. Yokohari
The changing governance of urban forests 37
N. Nagabhatla, E. Springgay and N. Dudley
Forests as nature-based solutions for ensuring urban
water security 43
P. Cariñanos, P. Calaza, J. Hiemstra, D. Pearlmutter and U. Vilhar
The role of urban and peri-urban forests in reducing risks
and managing disasters 53
J. Castro, S. Krajter Ostoić, P. Cariñanos, A. Fini and T. Sitzia
“Edible” urban forests as part of inclusive, sustainable cities 59
C. Y. Ji m
Protecting heritage trees in urban and peri-urban environments 66
FAO Forestry 75
World of Forestry 77
Books 79
Cover: T he Cheonggyecheon promen ade, Seoul,
Republic of Korea. The are a has been restored
in a major urban -renewal project to improve the
downtown environment. Cities ne ed forests
© Nicolas McComber
An internat ional journal of fores try and forest indu stries Vol. 69 2018/1
250
ISSN 0041-6436

EDITORIAL
M
ore than half the world’s population now lives in towns
and cities, and that proportion will continue to grow in
coming decades. If planned and managed well, cities
can be great places to live, but many urban developments cause
environmental havoc – ultimately leading to problems such as
urban “heat islands”, ooding, and air pollution. The cost for
citizens is borne in deteriorating well-being; the costs for the
planet include increased greenhouse gas emissions and other
waste and the degradation of soils and waterways.
Cities need forests. The network of woodlands, groups of trees
and individual trees in a city and on its fringes performs a huge
range of functions – such as regulating climate; storing carbon;
removing air pollutants; reducing the risk of ooding; assisting
in food, energy and water security; and improving the physical
and mental health of citizens. Forests enhance the look of cities
and play important roles in social cohesion; they may even reduce
crime. This, the 250th edition of Unasylva, takes a close look
at urban and peri-urban forestry (UPF) – its benets, pitfalls,
governance and challenges.
In the opening article, Borelli and co-authors describe the essen-
tial role that urban and peri-urban forests must play in meeting
global commitments on sustainable development. The United
Nations and other bodies have long recognized that unplanned
urban growth can drive poverty and inequality and cause social
and environmental problems on a global scale. Most recently, the
Sustainable Development Goals explicitly address the need for
sustainable urban development, aiming to “make cities and human
settlements inclusive, safe, resilient and sustainable”. Forests are
increasingly seen as essential elements of this, and many inter-
national organizations, including FAO, are assisting countries and
local governments to better integrate forests into city governance.
The article by Calaza and co-authors examines the role of UPF
as part of an overall strategy to develop green infrastructure – the
term used to describe the network of green spaces and water
systems delivering multiple economic, social and environmental
values and benets to an area. The article presents international
perspectives on the importance of good design in UPF and
suggests that it can help solve a number of urban problems.
Dobbs and co-authors use case studies in Australia, Brazil,
Colombia and the United States of America to demonstrate the
benets that urban and peri-urban forests can provide for city
residents. They also discuss some of the challenges that urban
forest planners and managers will need to meet in years to come.
In another article, Nowak sets out a four-step process for assess-
ing, modelling and monitoring urban forest structure, which
can have a profound impact on the benets and costs of urban
and peri-urban forests. This process, says Nowak, enables the
development of local forest management plans that optimize
forest structure to enhance human well-being.
Urban and peri-urban forests are often under pressure from
poor urban development, and better ways of governing them
are needed. According to Konijnendijk and co-authors, diverse
models of urban forest governance are emerging in which local
communities, not-for-prot organizations, municipal authorities
and the private sector all have roles to play in ensuring that the
benets and costs of UPF are shared equitably.
Nagabhatla and co-authors point out that ensuring a sustainable
water supply in cities looms as a major global challenge. They
advocate nature-based solutions, which are actions to protect
and manage ecosystems that both address societal challenges
and provide benets for human well-being and biodiversity.
Forests increase soil inltration, soil water-holding capacity and
groundwater recharge; regulate ows; reduce soil erosion and
sedimentation; and contribute to cloud cover and precipitation
through evapotranspiration. UPF, say the authors, will increas-
ingly be deployed as a cost-effective, nature-based solution for
managing water in cities.
Cariñanos and co-authors examine the role of UPF in reduc-
ing risks and coping with disasters. Poorly managed urban and
peri-urban forests can also create hazards, however, and the
article looks at how these can be handled with the overall aim
of increasing urban resilience to shocks.
The article by Castro and co-authors takes a somewhat different
tack, looking at the role of “food forests” in city sustainability.
It concludes that more work is needed to maximize the potential
of such forests as part of the green infrastructure of cities.
Finally, the article by Jim looks at the cultural role, management
and mismanagement of heritage trees, which are “outstanding”
trees to which societies attach special value. If a city can take
excellent care of its heritage trees, argues Jim, “it can inspire
condence in its capacity to care for all its urban and peri-urban
forests”. The article makes recommendations aimed at mitigat-
ing existing problems in the management of heritage trees and
improving professional practice.
The world will continue to urbanize for decades to come.
Villages will become towns, towns will become cities, and cities
will become megacities. Ensuring that these urban expanses are
both liveable and sustainable is a massive challenge to which
UPF advocates and practitioners must rise. Safeguarding and
sustainably managing forests and other green spaces in cities
will be crucial for the health and well-being of the planet and
its inhabitants. u

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Unasylva 250, Vol. 69, 2018/1
Cities can lead the way in meeting
the Sustainable Development
Goals and other globally
established objectives by deploying
urban and peri-urban forestry.
number of people living in urban areas
and, overall, 53 per cent of the world’s
urban population (United Nations, 2014).
Managing urbanization poses huge
challenges. Cities can be hubs of socio-
economic development, but the rapid
pace of urban growth and the limited
resources available to accommodate
increasing demand for food and basic
services can also present huge barriers
for the equitability and sustainability of
city development (United Nations, 2016).
Particularly in less-developed countries,
exponential urban population growth has
not been matched by a corresponding
increase in the availability of goods and
services such as clean drinking water,
Urban forests in the global context
S. Borelli, M. Conigliaro and F. Pineda
Simone Borelli, Michela Conigliaro and
Florencia Pineda a re in the Forestr y Policy and
Resources Division, Forest ry Depar tment, FAO.
© SIMONE BORE LLI
Above: A scene in an urban park
in Viterbo, I taly. Urban and peri-
urban fore sts are a crucial pa rt of a
sustainable future for the planet
T
he last century has been charac-
terized by (among other things)
increasing urbanization, with cities
worldwide expanding in both number and
size. For example, the world urban popula-
tion increased from 746 million people
in 1950 to 4 billion in 2015 (more than
a vefold increase), and this growth is
expected to continue in coming decades,
with low- and middle-income countries
projected to more than double and triple
their urban populations, respectively,
by 2050 (United Nations, 2016). Of the
world’s regions, Africa and Asia are
urbanizing fastest: Africa had the highest
urbanization rate of all the regions between
1995 and 2015; and Asia (already home
to 17 megacities1) has by far the largest
1 A megacity is a city with more than 10 million
inhabitants.

Unasylva 250, Vol. 69, 2018/1
4
adequate housing and sanitation, and
energy. In most less-developed countries,
urbanization has translated largely into
unplanned urban expansion accompanied
by unsustainable production and con-
sumption patterns, leading, in turn, to the
overexploitation of natural resources in
and around urban areas. As a result, cities
have become more vulnerable to natural
disasters and to the effects of climate
change, and many urban and peri-urban
communities are highly exposed to food
insecurity and poverty.
This article outlines the international
response to the urgent need to better
manage urbanization, specically through
the establishment, management and sustain-
able use of urban and peri-urban forests.
URBAN ISSUES IN
THE GLOBAL AGENDA
The international community and the
United Nations have widely acknowledged
that rapid, unplanned urban growth can
drive poverty and inequality, especially in
newly urbanizing countries. As far back
as 1976, the rst Habitat conference (held
in Vancouver, Canada) drew international
attention to the need to consider and discuss
the challenges posed by increasing urbani-
zation. Among other things, it led to the
creation of the United Nations Commission
on Human Settlements – an intergovern
-
mental body – and the United Nations
Centre for Human Settlements, the two
precursors of the United Nations Human
Settlements Programme, commonly known
as UN-Habitat. The second Habitat con-
ference, held in Istanbul, Turkey, in 1996,
ended with the endorsement of the Habitat
Agenda, a policy document containing more
than 100 commitments and 600 recom-
mendations for member countries, setting
a plan of action and urban sustainability
goals for the new millennium.
In 2015, urban sustainable development
was also at the heart of the two main
global development agreements endorsed
by the international community: the 2030
Agenda for Sustainable Development and
the Paris Agreement on climate change.
Building on the Millennium Development
Goals, the 2030 Agenda (which includes
17 Sustainable Development Goals –
SDGs) calls on countries to “mobilize
© SIMONE BORE LLI
Participants in
the Habitat III
conference, held
in Quito, Ecuador,
in 2016, enjoy th e
ecosystem services
provided by trees

5
Unasylva 250, Vol. 69, 2018/1
efforts to end all forms of poverty, ght
inequalities and tackle climate change,
while ensuring that no one is left behind”.
The 2030 Agenda recognizes urban
sustainability as a key element for
achieving sustainable development and
includes a specic goal on urban devel-
opment (SDG 11): “make cities and
human settlements inclusive, safe, resil-
ient and sustainable”. About one-third
of the 231 indicators in the SDG Global
Monitoring Framework are related directly
to urban policies with clear impacts on
cities and human settlements and can be
measured at the local level (UN-Habitat,
2017).
The key role of cities in achieving
the sustainability goals set in the Paris
Agreement was recognized at the 22nd
Conference of the Parties to the United
Nations Framework Convention on
Climate Change, held in Marrakech,
Morocco, in 2016. Parties agreed that,
given that cities are the main source of
carbon emissions and contain most of the
human population (UN-Habitat, 2011), the
most important efforts for climate-change
mitigation and adaption will have to be
implemented in urban areas.
The Habitat III conference, held in
Quito, Ecuador, in 2016, put equality
and socio-economic and environmental
sustainability at the heart of discussions
on sustainable urban development. The
main outcome of that conference was the
endorsement of the New Urban Agenda
(NUA), which sets out a global strategy
for addressing urbanization issues in
coming decades. According to the NUA,
cities must develop urban strategies that
are people-centric, helping their citizens
to thrive rather than simply survive. The
NUA is based on three “interlinked”
principles: leave no one behind; ensure
sustainable and inclusive urban economies;
and ensure environmental sustainability.
The NUA builds on the assumption that
well-planned and -managed urbanization
can be a powerful tool for sustainable
development in both developing and
developed countries. It also stresses its
links with the 2030 Agenda and its role
in implementing the latter.
ROLE OF URBAN FORESTS
IN THE NUA AND THE SDGs
The NUA and the SDGs, particularly
SDG 11, highlight the importance of green
spaces in improving living standards in
cities, increasing community cohesion,
improving human wellness and health,
and ensuring sustainable development,
with the text of the NUA echoing the
wording of the SDGs. Thus, countries
commit themselves to the promotion of
safe, inclusive, accessible and green public
spaces (SDG 11) that:
•
provide urban dwellers with multi-
functional areas designed for social
interaction and inclusion (SDGs 10
and 11);
•
contribute to human health and well-
being (SDG 3);
•
promote economic exchange, cultural
expression and dialogue among a
wide diversity of people and cultures
(SDG 8); and
• are designed and managed to ensure
human development and build
peaceful, inclusive and participatory
societies (SDGs 10 and 16), as well as
to promote living together, connectiv-
ity and social inclusion.2
© SIMONE BORE LLI
Residents and
tourists in Lju bljana,
Slovenia, enjoy
outdoor leisure time
in the shad e of a
large tree. There
is evidence of an
inverse relationship
betwee n tree
canopy cover and
crime rate s. Green
spaces increase
social cohesion and
provide documented
health benets
2
The NUA addresses the se bu llet poi nts in para-
graphs 13b, 13h, 14c, 37, 38, 51, 53, 65, 67, 71,
100 and 109.

Unasylva 250, Vol. 69, 2018/1
6
Urban forests, social cohesion and
human health
If properly planned and managed,
urban and peri-urban forests – dened
as “networks or systems comprising all
woodlands, groups of trees, and individual
trees located in and around urban areas”
(FAO, 2016) – can make valuable contribu-
tions to the quality of urban green spaces.
In Baltimore, United States of America,
for example, a strong inverse association
was observed between crime rates and
tree-canopy cover (adjusting for many
confounding factors); this association was
true for both public and private lands but
was strongest for public lands that were
accessible to all (Troy, Grove and O’Neil-
Dunnea, 2012). A study on the collective
efcacy3 of various urban features found
that parks are considered community
assets. They bring people in surrounding
areas to common places to participate in
leisure activities – at times when people
are most likely to be open to what they
see around them and more receptive to
others because they are pursuing recrea-
tion together and sharing common spaces
(Cohen, Inagami and Finch, 2008).
Another study, in the Netherlands
(Maas et al., 2009), found, after adjust-
ing for socio-economic and demographic
characteristics, that less green space in
people’s living environment coincided
with feelings of loneliness and with a
perceived shortage of social support.
Overall, information collected through
interviews showed that people with more
green space in their living environments
felt healthier, had experienced fewer health
complaints in the previous 14 days, and
had a lower self-rated propensity for psy-
chiatric morbidity than those with less
access to green areas. The study also
found that the relationship between green
space and health indicators was strongest
and most consistent for the percentage
of green space within a 1-km radius of
people’s homes. A report by The Nature
Conservancy (2017) considered that, given
the increasingly well-documented benets
of urban and peri-urban forests for human
health, “there is a strong business case for
more investment in urban trees”; thus, “the
health sector (whether public or private
institutions) could supply some nancial
resources that help partially pay for activi-
ties in the urban forestry sector”.
Socio-economic development
In the NUA, green spaces are no longer
viewed simply as aesthetic features
in landscapes but as drivers of socio-
economic development that can be
leveraged to increase socio-economic
value, including by increasing property
values, facilitating business and public and
private investments, and providing liveli-
hood opportunities for all (SDGs 8 and 10).
Hedonic models used to determine the
effects of green spaces and urban and peri-
urban forests on house sale prices have
found, for example, that the presence of
green spaces within 80–100 m of a home
increases its price by 7 percent (Conway
et al., 2010). Wolf (2003) used contingent
valuation methods to assess correlations
between variations in urban forest char-
acter and shopper behaviour in a number
of cities in the United States of America,
nding that consumers were 9–12 percent
more likely to make their purchases in
shopping districts that had trees than in
comparable districts without trees.
Environmental benets
In line with SDG 13 (climate action) and
SDG 15 (life on land), the NUA calls for
the sustainable management of natural
resources in cities and human settlements
in a manner that protects and improves
urban ecosystems and their ecosystem
services, reduces greenhouse gas emis
-
sions and air pollution, and promotes
disaster risk management. Urban and
peri-urban forests and trees help mitigate
climate change by directly capturing
and storing atmospheric carbon dioxide.
Also, trees provide shade and reduce wind
speeds, thereby indirectly lowering carbon
emissions by reducing the need for air con-
ditioning and heating and thereby cutting
emissions from power plants (Nowak et al.,
2013). Shaded surfaces can be 11–25 °C
cooler than the peak temperatures of
unshaded materials (Akbari et al., 1997);
shading, therefore, can extend the useful
life of street pavement by as much as ten
years, thus reducing emissions associated
with petroleum-intensive materials and the
operation of heavy equipment required
to repave roads and haul away waste
(McPherson and Muchnick, 2005).
Urban areas are generally warmer than
their surroundings – typically by 1–2 °C
but by as much as 10 °C in certain climatic
conditions (Bristow, Blackie and Brown,
2012; Kovats and Akhtar, 2008). Urban
and peri-urban forests can reduce this
“heat island” effect by providing shade
and reducing urban albedo (the fraction
of solar radiation reected back into the
environment) and by cooling through
evapotranspiration (Romero-Lankao and
Gratz, 2008; Nowak et al., 2010).
People in urban areas face many poten-
tial climate-related risks, such as the
increased incidence and severity of storms
and ooding. Urban trees can contribute
to stormwater management in a number of
ways. Stormwater run-off can be reduced
by the evaporation of rainfall intercepted
by tree canopies and through transpiration,
and stormwater quality can be improved
by the retention of pollutants in soils and
plants (Stovin, Jorgensen and Clayden,
2008). Reducing stormwater ows also
reduces the risk of hazardous combined
sewer overows (Fazio, 2010).
By increasing social cohesion, urban and
peri-urban forests can help prevent deaths
related to, among other things, the effects
of climate change. Community stability is
an essential component of effective long-
term sustainable strategies for addressing
climate change (Williamson, Dubb and
Alperovitz, 2010). For example, the death
rate in the severe 1995 Chicago heatwave
3 Collective efcacy, a form of social capital, is a
standa rdized and well-tested agg regate measure
of individual perceptions of “social cohesion
among neighbors combined with the will ingness
to intervene on behalf of the common good”
(Sampson, Raudenbush and Earls, 1997).

7
Unasylva 250, Vol. 69, 2018/1
varied greatly by neighbourhood, due in
part to differences in community cohesion
(World Health Organization, undated).
ROLE OF INTERNATIONAL
ORGANIZATIONS
There is increasing evidence that
government institutions are no longer
the only important actors in decision-
making processes, and a key ingredient
of sustainable urban and peri-urban forest
management, therefore, is inclusive govern-
ance (Lawrence et al., 2013). Civil-society
actors are increasingly recognized as
important partners in policy discussions and
in promoting the potential benets of urban
and peri-urban forests. Intergovernmental
organizations and non-governmental
organizations (NGOs) are playing cru-
cial roles in closing knowledge gaps by
conducting action research, providing
policy guidance and building institutional
capacities. Such organizations also facili-
tate dialogue between countries and cities
and with civil society to increase people’s
awareness of the need to live more sustain-
ably (Al Mubarak and Alam, 2012) and,
ultimately, to achieve the full integration
of urban and peri-urban forests and city
planning and governance.
FAO supports its member countries
through the development of technical
guidelines and regional networks and
the implementation of eld projects. In
addition to its work on urban and peri-
urban forestry, FAO has initiatives and
programmes aimed at helping achieve
SDG 11, and it is collaborating increas-
ingly with partner organizations such as
UN-Habitat on urban–rural linkages and
land tenure.
UN-Habitat works in human settlements
worldwide – from villages to megacities.
The United Nations Environment
Programme (UNEP) addresses the role
of cities in climate change through its
Urban Environment Unit. Integrating their
complementary expertise, UN-Habitat
and UNEP have developed the Greener
Cities Partnership, which advocates and
promotes environmental sustainability in
urban development and the mainstreaming
of environmental considerations in urban
policymaking. For more than two decades,
© SIMONE BORE LLI
A family in the
Republic of Korea
look out over a forest
canopy. Cities have
the opportunity
to lead the way
towards a gre ener
and healthier planet
that ensures the
well-b eing of all
people by investing
in nature -based
solutions as a key
tool for achieving
sustainable urban
development

Unasylva 250, Vol. 69, 2018/1
8
the Greener Cities Partnership has been
an incubator of ideas for collaboration
and innovation while also serving local,
national and international stakeholders
through various activities.
Launched in 2016, United for Smart
Sustainable Cities (U4SSC) is a joint
initiative of 16 United Nations agencies
and programmes to assist in achieving
SDG 11. Coordinated by the International
Telecommunication Union and the United
Nations Economic Commission for
Europe, U4SSC has developed a set of
international key performance indicators
and a related data-collection methodology
to assess the contributions of information
and communication technology to the
creation of smarter and more sustainable
cities. A number of the key performance
indicators are designed to assess the avail-
ability, accessibility and management of
green and natural spaces in cities.
Environmental NGOs and international
organizations such as the World Wide
Fund for Nature (WWF), the International
Union for Conservation of Nature (IUCN),
The Nature Conservancy and Conservation
International are playing growing roles
in urban and peri-urban forest govern
-
ance (Duinker et al., 2014). The aim of
WWF’s One Planet Cities Challenge, for
example, is to support cities in enabling
all their citizens to thrive while respect-
ing the planet’s ecological limits. WWF’s
Urban Solutions for a Living Planet is a
platform for showcasing best practices in
sustainable urban development. WWF
also works with urban planners around the
world through its Financing Sustainable
Cities programme to promote investment
in sustainable urban infrastructure.
In 2000, IUCN’s World Commission on
Protected Areas, a global network to help
governments and others plan protected
areas and integrate them into all sectors,
created the Urban Conservation Strategies
Specialist Group. This group works to
strengthen the ability of the conservation
community to serve urban people, places
and institutions.
100 Resilient Cities is a not-for-prot
organization dedicated to helping cities
become more resilient to the physical,
economic and social challenges they face.
The 100RC global network provides cit-
ies with resources to develop resilience
strategies. For example, the network gives
guidance on establishing the position of
“chief resilience ofcer” in governments to
lead resilience efforts and provides access
© SIMONE BORE LLI
Trees line this green space in
Belgium. Urban and peri-urban trees
and forests provide a wide range of
environmental benets, in addition
to their contributions to soc ial
cohesion and human well-being

9
Unasylva 250, Vol. 69, 2018/1
to innovative solutions, service providers,
and potential partners from the private,
public and NGO sectors. Membership
of the 100RC network enables cities to
learn from and help each other in achieving
common objectives.
CONCLUSION
Achieving the goals and targets of the 2030
Agenda for Sustainable Development, the
Paris Agreement and other agendas and
strategies requires a joint effort to move
from global commitment to local imple-
mentation. Through urban and peri-urban
forestry and greening solutions, cities have
the opportunity to lead the way towards a
greener and healthier planet that ensures
the well-being of all people. To do so
requires that city administrators:
•
involve all key stakeholders in the
governance of urban and peri-urban
forests;
•
develop policy and legal frameworks
that support the integration of urban
and peri-urban forests and other
green spaces in overall “green cities”
policies; and
•
invest in nature-based solutions as
a key tool for achieving sustainable
urban development.
Networking and the exchange of experi-
ences and knowledge among cities and
disciplines are also crucial for achieving
the global goals set by the international
community (FAO, 2016). The C40
Cities Climate Leadership Group, Local
Governments for Sustainability (ICLEI),
URBACT and the Carbon Neutral Cities
Alliance are some of many active national,
regional and global networks that are shar-
ing experiences and making joint efforts
to increase the sustainability of urban
development and raise local awareness of
the key role that forests and green spaces
can play in sustainable urban development
worldwide.
First World Forum on Urban Forests
The increasing interest in urban and
peri-urban forestry suggests that the
time is ripe to initiate a global process
to enhance communication and network-
ing among practitioners, scientists and
decision makers, support the NUA and
optimize the potential of urban and peri-
urban forests in achieving the SDGs.
Thus, the rst World Forum on Urban
Forests will be held in Mantova, Italy,
on 28 November–2 December 2018 with
the aim of highlighting positive examples
of urban and peri-urban forest planning,
design and management. These examples
will be drawn from cities with diverse
cultures, forms, structures and histories
that have used urban and peri-urban for-
estry and green infrastructure to develop
economic and ecosystem services and
strengthen social cohesion and public
involvement. The event will bring together
representatives of international organi-
zations, national and local governments,
research and academic institutions, NGOs,
urban planners, urban foresters, arborists,
landscape architects and designers, and
professionals from many other sectors to
exchange experiences and lessons learned.
Participants will also discuss long-term
collaboration on the development of
urban and peri-urban forest strategies
and the identification of nature-based
solutions towards a greener, healthier and
happier future. u
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en/index3.html u

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Urban and peri-urban forests are
the most important components
of green infrastructure in
cities – when well planned,
designed and managed.
(World Health Organization, 2017). Climate
change, which is leading to increases in
oods and heatwaves, is complicating
the situation.
A major global challenge is to design
and customize cities to overcome such
problems. A possible strategy, supported
by the European Union (EU), involves
“nature-based solutions”. The EU empha-
sizes green infrastructure
1
in cities for
its multifunctionality, multiscalability
and governance attributes. Urban and
peri-urban forests are arguably the most
Building green infrastructure and urban landscapes
P. Calaza, P. Cariñanos, F. J. Escobedo, J. Schwab and G. Tovar
Pedro Calaz a is Professor of Landscap e
Archite cture at Escuela Gal lega del Paisaje,
Spain, Dean of Colegió Ocial de Ingenieros
Agronomos, Spain, an d a member of the Silva
Mediterranea Working Group on Urban and
Peri-urban Forestry (FAO WG7).
Paloma Cariña nos is Professor of Botany at the
University of Granad a, Spain, and a member of
FAO WG7.
Francisc o J. Escobedo Montoya is Professor at
Del Rosario University, Colombia.
Jame s Schwab is a consu ltant and urban
planni ng specialist based i n the United States of
America.
Germán Tovar is a specialist in the Ofce of the
Mayor of Bogotá, Colombia.
© PEDRO CALAZ A
Above: Grand Parc, Versailles
Gardens, France. Sustainably
managed urban and peri-urban
forests ca n provide a wide range of
ecosystem s ervices that will increase
the resilience of cities and societies
to shocks and rapid change
T
he accelerated growth of the human
population has been accompanied
by a process of rapid and often
poorly planned urban development, dra-
matic changes in lifestyle and poor dietary
habits. Today, largely due to emigration
from rural areas, more than 54 percent
of the world’s population lives in cities.
The combination of globalization, rapid
unplanned urbanization, and ageing
populations is leading to an increase in
the incidence of non-communicable dis-
eases, the major cause of global mortality
1 The EU denes green infrastructure as “a stra-
tegically plan ned network of hig h-qualit y nat ural
and semi-nat ural areas with other environmen-
tal features, which is designed and managed
to deliver a wide range of ecosystem services
and protect bio diversity in both r ural and urban
settings” (European Commission, 2013).

Unasylva 250, Vol. 69, 2018/1
12
important elements of green infrastructure,
connecting cities with nature and provid-
ing a wide range of ecosystem services.
This article examines the role of urban
and peri-urban forests as part of an overall
strategy to develop green infrastructure by
presenting various international perspec-
tives on the importance of proper design
in urban and peri-urban forestry (UPF).
In so doing, we propose that UPF can
help solve urban problems through multi-
scalar, context-specic, socio-ecologically
relevant strategic approaches.
A SOLUTION FOR IMPROVING
WELFARE IN MODERN CITIES
As rural and agricultural communi-
ties have transformed into urban and
technological societies, UPF has evolved
from a practice with a limited purpose,
such as growing certain tree crops and
beautifying landscapes, to a strategic
approach for meeting economic, social and
environmental objectives. Increasingly,
the scientic, practical, management and
planning knowledge, tools and lessons
derived from UPF – mostly from Australia,
Canada, Germany, the United Kingdom of
Great Britain and Northern Ireland, and
the United States of America – are being
used to help solve the problems caused
by increasing urbanization. European and
North American countries have established
UPF teaching and research institutions
and developed national-level and local
political and regulatory tools and laws for
conserving, regulating and incorporating
the use of urban and peri-urban forests.
Recently, too, Brazil, China and other
developing countries have started using
UPF to increase food security, create jobs,
conserve biodiversity and mitigate the
impacts of climate change. Rapid urban
growth in Africa and South Asia provides
an opportunity to adopt the latest ndings
and knowledge on UPF to address food
security, human health and the environ-
ment in cities.
© PEDRO CALAZ A
Leidsebosje, Amsterdam, the Netherlands.
Urban and p eri-urban forestry is
evolving from a limited practice of
tree-growing to the strategic use of trees
to address multiple economic, social
and environmental issues

13
Unasylva 250, Vol. 69, 2018/1
Nevertheless, UPF science, practices and
technologies need to continue to evolve
(Livesley, Escobedo and Morgenroth,
2016). UPF is more than planting or prun-
ing trees – urban and peri-urban forests
are part of multiscalar socio-ecological
ecosystems (Figure 1) that provide a range
of benets and incur costs. Therefore,
ensuring that UPF makes an optimal
contribution to the resilience and sustain-
ability of modern cities requires long-term
planning, knowledge of the biophysical,
socio-ecological and socio-economic
context, and participatory approaches
(Livesley, Escobedo and Morgenroth,
2016).
Solving diverse problems
Australia and China – two countries with
very different political systems – are both
using UPF to solve problems. In Australian
cities, participatory processes are taking
place for the development of adaptive
management plans and governance in order
to integrate urban and peri-urban forests
as essential components of city planning
and management. China, through national
decrees, has fostered large-scale urban
reforestation to create green spaces for
recreation and to mitigate air pollution
and improve public health. Costa Rica and
some Andean countries have developed
tools such as payments for ecosystem
services, which are helping improve the
management of peri-urban forests to
maintain water quality and conserve bio-
diversity. In Japan and Scandinavia, UPF
is being used as a strategy for reducing
stress and thereby improving public health.
Chile recently implemented policies on
urban and peri-urban forests as a way of
offsetting industrial-sector greenhouse
gas emissions.
Climate change
Climate change is expected to increase the
incidence and severity of extreme weather
events, such as drought, heat and heavy
rains. Extreme heat events – such as those
in France in 2003, 2006 and 2017 – can
have major impacts on human health in
cities. A heatwave in the United States
of America in 1995 caused the deaths of
more than 700 people, most of them elderly
and disabled. The casualties of extreme
heat events most commonly occur in
neighbourhoods that lack social support
for the most vulnerable people and where
there is less access to human services
and to shaded areas. UPF is increasingly
being used to reduce the impacts of such
extreme heat events in cities (Livesley,
Escobedo and Morgenroth, 2016), includ-
ing in tropical America and Asia. Urban
and peri-urban forests can also mitigate
other extreme weather events: in some
parts of the Caribbean, the conservation
of urban trees and mangroves seems to
have reduced the damage caused by recent
hurricanes (Escobedo et al., 20 09). Many
North American cities are implementing
measures to incorporate green infrastruc-
ture as a way of increasing resilience.
1
Socio-ecological scales related to
urban for ests, their management
and ecosystem services
Continent and global
Ecoregion
Watershed
Tre e cover
Groups of
trees
Tre e
International organizations
Nation
Region
Municipality
Neighbourhood
Home/
family
Organizations
1 000 km2
Individuals
10 m2

Unasylva 250, Vol. 69, 2018/1
14
Economic, social and
environmental benets
The science and practice of UPF have
evolved as understanding of the benets
has increased and with the adoption of
new technologies (Livesley, Escobedo
and Morgenroth, 2016). For example, the
measurement of energy savings due to the
shading effects of trees has changed the
public discussion on the costs and benets
of green infrastructure. Trees are not only
aesthetic amenities, they are also strat-
egies for economic investment and savings.
Depending on the context, only relatively
minor efforts are needed to determine
and promote the social and environmental
benets of urban and peri-urban forests.
THE PUBLIC ADMINISTRATION OF
URBAN AND PERI-URBAN FORESTRY
Most cities divide public spaces among,
and deliver administration through,
various agencies with differing objectives.
Parks, water bodies, railway easements,
roads, conservation areas and other spaces,
which might all feature trees, may be man-
aged in very different ways by different
agencies. Many such agencies, especially
those with no statutory conservation func-
tion (and therefore no budget for it), may
completely ignore tree management. A
key challenge for cities, therefore, is to
increase coordination and collaboration
among agencies to bring to bear a con-
sistent approach to the management of
urban and peri-urban forests. Such an
intersectoral approach may produce better
results than centralizing forest manage-
ment in a single agency.
Multisectoral approach
In many places, urban and peri-urban for-
est management is still site-specic and
fragmented, and the concept of achieving
citywide functionality, therefore, is lacking.
The lack of cohesion reduces the effective-
ness of UPF in inuencing city landscapes
and the lives of residents. The challenge
facing many cities is to create institutional
structures that allow the comprehensive
planning and management of the forest
estate across a city. Most cities lack an
agency able to regulate, monitor and coor-
dinate the forest management actions of
the various public agencies, and the lack of
coordination among agencies also reduces
the potential for the participation of private
companies and civil society. One city that
does feature such an institutional architec-
ture is Bogotá, Colombia: the municipal
© FRANC ISCO J. ESCOBEDO MONTOYA
Bosque de Chapultepec, Mexico City,
Mexico. A challenge facing many cities
is to create institutional structures
that allow the comprehensive planning
and management of urban forests
across land uses and tenure

15
Unasylva 250, Vol. 69, 2018/1
2
Instituti onal structure f or urban tree management in Bogotá , Colombia
SECRETARÍA DISTRITAL DE AMBIENTE
(Environmental Authority of Bogotá)
Determines the urban tree management policy
Carries out urban silvicultural planning for Bogotá
Monitors, evaluates and regulates the entities involved in urban
tree management
Botanical Garden of Bogotá
Administers the georeferenced census of urban trees
Advises other entities on tree- cover management
Conducts research on urban trees
19 local mayorships Carry out root-pruning on trees that are causing damage to
platforms and sidewalks
Unidad Administrativa Especial de Servicios
Públicos (Special Public Services Unit)
Carries out tree-pruning throughout the city following a pruning
plan, by species, type of pruning and intervention cycle
Maintains a census of urban trees
Instituto de Desarrollo Urbano (Institute of Urban
Development – public) Manages trees in the construction of public works
Empresa de Acueducto, Alcantarillado y Aseo de
Bogotá (Water and Aqueduct Company of Bogotá) Manages trees in and around the city’s water system
(i.e. rivers, streams and canals)
Agencia de Infraestructura Nacional (National
Infrastructure Agency) Manages urban trees in railway easements
Codensa and Grupo Energía de Bogotá (electricity
supply companies) Manage trees of potential risk to the electricity supply
Instituto de Recreación y Deporte (Institute for
Recreation and Sports) Manages trees in city parks
Fireghters and Instituto Distrital de Gestión
de Riesgos y Cambio Climático (District Institute for
Risk Management)
Manage trees of potential risk in res and other disasters
District Treasury of Bogotá Collects, in a separate account, funds paid for harvesting rights
and nes paid for damaging urban forest resources
Fondo Distrital para la Gestión de Riesgo y
Cambio Climático (District Fund for Risk
Management and Climate Change)
Disburses funds to reduce the risks posed by urban trees

Unasylva 250, Vol. 69, 2018/1
16
environmental authority there coordinates
the management of 31 public agencies that,
to a greater or lesser extent, have roles in
UPF (Figure 2).
Master plans
A good starting point for a coordinated
approach to UPF is to conduct a geo-
referenced tree census to provide the
basis for analysis and the development and
implementation of an urban forest master
plan. In general, the most sensitive issues
in such plans are those associated with risk
management, tree felling, and maintaining
the existing forest stock. Underlying – but
less visible – aspects are increasing the
provision of goods and ecosystem services;
species selection; biodiversity conserva-
tion; the connectivity of green spaces; and
pest and disease management.
UPF generally attracts only small
budgets; therefore, longevity is an
important criterion in species selection
in the establishment of urban and peri-
urban forests. Maintenance costs are also
important. In Bogotá, for example, the tree
species caucho sabanero (Ficus andicola)
is being planted less and less. This native
species is resilient, well adapted to the
area and well accepted by residents; it
has proven prone to pests and diseases,
however, meaning that maintenance costs
are ten times higher than for other species.
Providing space for forests in new urban
and peri-urban areas is often a signicant
challenge because of land scarcity and
high land values. The urban growth model,
which may be either low-density or high-
density (or on a scale between these two
extremes), is a major determinant of
policies on the creation of public green
space. Allocating large blocks of land in
industrial or residential areas for ecological
connectivity or recreation requires strong
political effort and a clear justication, as
established in the urban forest master plan.
Such plans are essential tools, therefore, for
enabling municipalities to plan new urban
and peri-urban forests in the ux created
by urban growth dynamics.
MULTISCALAR DESIGN:
FROM INDIVIDUAL TREES TO
COMPREHENSIVE STRATEGIES
The design of urban and peri-urban forests
should consider various scales, from the
individual tree to the citywide forest (FAO,
2016). It should also address the structural,
functional, ecological, landscape, social
and cultural requirements for ensuring
multifunctionality.
Among structural aspects, the mor-
phology of species (e.g. trees, bushes
and grasses) and their distribution in the
available space should be considered with
a view to creating environments with
© PEDRO CALAZ A
A London plane tree
(Platanus spp.) in front
of the Strausberger
Platz, Berlin,
Germany. The de sign
of urban and peri-
urban fore sts should
consider various
scales , from the
individual tree to the
citywide forest

17
Unasylva 250, Vol. 69, 2018/1
varying vertical structures. Species may be
selected to favour certain ecosystem func-
tions. Tree size, longevity and growth type
are other elements to consider in design
(Gustavsson, 2002); a diversity of species
with different morphologies and functions
occupying different ecological niches
reduces the risk of widespread mortality
in the face of a given threat and may also
mean lower maintenance requirements.
Access and infrastructure are two of the
most relevant functional aspects of urban
and peri-urban forest design. All residents
should have access to a diverse range of
open spaces to meet their varying needs
and expectations, regardless of age, ethnic-
ity, culture or disability. The elimination
of physical and legal barriers to urban and
peri-urban forests is not only the best way
of ensuring that all people have access to
a healthy environment, it is a principle
of environmental justice2 that should be
promoted by design and planning (Nilsson,
Sangster and Konijnendijk, 2011).
The resilience of cities in the face of
climate change and associated extreme
weather events will depend on the main-
tenance of ecological processes. Ensuring
urban and peri-urban connectivity is essen-
tial for maintaining ecological processes
such as succession and transition.
Landscape design is important for
conveying the “message” of UPF. For
example, a lack of geometric lines in
planting arrangements will help convey
a sense of spontaneity and closeness to
nature; geometric designs, in contrast, can
convey closeness to urban design (Bell
et al., 2005). The planting of individual
trees should take the environment into
account: for example, trees planted in
historically important places should not
disrupt the landscape but rather become
a discreet part of it. On the other hand,
the role of tree alignment zones in new
areas is to strengthen architecture and
aesthetics and improve health. The general
aim is to achieve a multisensory experi
-
ence, producing views, sounds, smells and
other stimuli that reinforce the sense of
connection between humans and nature.
Finally, the sociocultural element should
be a priority; urban and peri-urban forests
should be politically neutral places that
enable environmental justice and the
integration of social groups (O’Brien
et al., 2017). It is essential to consider
the “forest culture” – that is, the way in
which a community views and uses urban
and peri-urban forests according to their
diversity and biogeographical features.
In northern Europe, for example, forest
designs should take into account the
need both for light and for contact with
nature; in the Mediterranean, urban and
peri-urban forest designs should provide
cooling shade and be conducive to the
prevailing outdoor lifestyle.
Table 1 summarizes a range of
international approaches to urban and peri-
urban forest planning to achieve various
objectives.
2 Environmental justice is the fair treatment and
meaningful involvement of all people regard-
less of race, colour, national origin or income
with respect to t he development, implementation
and enforcement of environmental laws, regula-
tions and policies (United States Environ mental
Protection Agency, undated).
© PEDRO CALAZ A
The publicly
accessible Saxon
(“Saski”) Garden,
Warsaw, Poland.
Urban and p eri-urban
forests should be
politically neutral
places that enable
environmental justice
and the integration
of social groups

Unasylva 250, Vol. 69, 2018/1
18
TABLE 1. International experiences in urban and peri-urban forestry
Country City Name Goal Description
Germany Berlin Biotope Area
Factor (1984)
To regulate new urban development with
an ecological approach
Part of the area to be developed is to be used for green
spaces in which the original vegetation is to be kept or new
plant cover planted. Guidelines are provided for landscape
planning and design, species protection, and conservation.
One of the main advantages of the Biotope Area Factor is
that it is exible in the design of the urban forest and enables
stakeholder participation. Since the Biotope Area Factor
was introduced in the design and planning of green areas,
the provision of vegetation in heavily populated areas has
signicantly reduced the impacts of climate change, such as
heatwaves, ooding and storms
Sweden Mälmo Green Space
Factor (2001)
To regulate urban development for new
urbanization areas using an ecological
approach
The approach is similar to the Biotope Area Factor, with
various versions and biotopes
USA Seattle Urban Forest
Stewardship
Plan
Seattle Green
Factor
•To create an ethical model of urban
forest management for all stakeholders
•To make specic improvements with
a view to achieving a net increase
in the functions of urban forests and
the associated economic, social and
environmental benets
•To increase forest cover by 30 percent
•To strengthen the health and longevity
of urban forests, improve the quality of
species and eliminate invasive species
The management plan is framed within the Trees for Seattle
Strategy, which brings together all efforts on forests in the
city. A section of the strategy focuses on the design and
safety of street trees and their role as elements for reducing
driving speeds, crime and domestic violence without
reducing the important aesthetic values they provide.
The Seattle Green Factor is an adaptation of the Mälmo
Green Space Factor, which is being incorporated into other
cities in the United States of America
Australia Sydney Greening
Sydney Plan,
2012
•To protect and maintain existing urban
forests
•To increase canopy cover
•To improve biodiversity
•To increase knowledge and
commitment in the community
Strategy aimed at developing and protecting urban and
peri-urban forests
Sweden Umeå Young urban
forests
To develop new urban forests Young urban forests have been created by regenerating
previous forests or by planting trees, the latter seeking to
perform predetermined functions entailing specic forest
treatments that need to be permanently maintained. An
experimental study was carried out in Umeå on a 2.1-hectare
plot that had been reforested 20 years before. In this forest,
12 small forest compartments were created using various
thinning methods, with different functions and traditions,
creating areas for relaxing and meditating in isolation;
children’s play areas; natural-looking spaces; areas subject
to heavy management for aesthetic purposes; and various
samples of local forest types
Norway
Akerselva
(Oslo)
To create multisensory environments A corridor was created along the Akerselva River to enable
downtown residents to travel to nearby parks hosting
14 “quiet areas” for contemplation
USA New
Yor k
Program
PlaNYC: 2030
To ensure accessibility The aim is for every inhabitant to have a green area within a
10-minute walking distance
Singapore
To provide opportunities to be outdoors
and enjoy nature
The integration of 200 km of pathways through elevated
runways to enable inhabitants in different parts of the city to
access parks
Japan Nagoya To promote actions to actively support
nature conservation
Conserve 10 percent of land next to the city boundaries as
an unmanaged area and protect it as a nature reserve
USA Phoenix To encourage actions to actively support
nature conservation
17 000 hectares of desert were purchased to avoid the
negative ef fects of urban expansion, and this area was
designated as a nature conser vation site
USA Portland To invest in social infrastructure that
helps urban dwellers understand nature
Investment of more than 5 percent of the annual city budget
in biodiversity. The aim is to attain one of the highest tree-
canopy covers among the nation’s cities (29.9 percent)

19
Unasylva 250, Vol. 69, 2018/1
TREE SPECIES SELECTION
AND PLANTING DESIGN IN
URBAN LANDSCAPES
Tree planting is an important tool for
improving cities, but it needs to be done
properly; often, trees are selected for use or
planting with no technical criteria. Many
strategies can be used for incorporating
trees in cities. For example, FAO (2016)
identies ve main types of urban and
peri-urban forests: 1) peri-urban forests
and woodlands; 2) city parks and urban
forests (> 0.5 hectares); 3) pocket parks
and gardens with trees (< 0.5 hectares);
4) trees on streets or in public squares; and
5) other green spaces with trees. All these
are important resources for the spatial
design and planning of an urban and peri-
urban forest estate. Urban and peri-urban
forest design should comply with basic
landscape design principles addressing
unity and structure, scale, proportion and
balance, space division and denition, light
and shade, colour, texture and shape.
Trees bring buildings closer to the human
scale, and they enable the creation of
spaces by providing a range of textures,
light, shapes and seasonality (Arnold,
1980). Trees can be customized to suit
almost any situation, thus addressing
problems such as stormwater management
and climate change and achieving specic
aesthetic objectives.
Leaf area
Although, in general, the more trees in a
city the better, the most important param-
eter is canopy cover because of the role that
leaf area plays in the services provided by
urban and peri-urban forests. The leaves of
trees provide the most important ecosystem
services of UPF – such as the maintenance
of water quality; thermal regulation; the
capture of volatile organic compounds and
other air pollutants (e.g. sulphur dioxide,
nitrogen oxides, ozone, and ne particulate
matter such as soot, dust, pollen, and emis-
sions from diesel vehicles); and oxygen
production. Such services improve human
health (e.g. asthma and related illnesses)
and help reduce other complex air-quality
problems (such as ground-level ozone,
smog and the urban “heat island” effect).
In Spain, one of the goals of Barcelona’s
recently published Urban Forest Master
Plan 2017–2037, therefore, is to increase
tree canopy cover by 5 percent of the land
area, thus achieving a forest cover in the
city of 30 percent.
Big trees
Cities need big trees, and one of the aims
of design, therefore, should be to maximize
tree size. Large-stature trees deliver up
to eight times the benets compared with
small trees (United States Forest Service,
2004); even at maturity, small-stature trees
do not come close to providing the same
magnitude of benefits. A strategically
located large-stature tree can contribute
signicantly to mitigating the urban heat
island effect and conserving energy.
Choosing tree species that will be large
at maturity, planting these on suitable
sites, and managing them to ensure they
grow strong and healthy will maximize
carbon sequestration. The use of large-
stature trees can multiply the bottom-line
benets of urban and peri-urban forests:
in one theoretical study of trees at age 30
(projected to life expectancy), the annual
benets generated were USD 55 for large
trees, USD 33 for medium-sized trees, and
only USD 23 for small trees (McPherson
et al., 2003).
Diversity
The Santamour rule (sometimes called
the “10 percent” rule) proposes maxi-
mum percentages for tree species, genera
and families in a plantation (Figure 3).
This rule, which was proposed by Frank
Santamour (1990), a geneticist at the United
States National Herbarium, states that no
more than 10 percent of any one species, no
more than 20 percent of any one genus, and
no more than 30 percent of any one family
should be planted; others have proposed a
“5 percent” rule. The objective behind the
rule is to maximize protection against pest
outbreaks. Thus, another important goal of
the Barcelona Urban Forest Master Plan
is to achieve a tree diversity in which no
species represents more than 15 percent
of the total. Urban forest design should
3
The Santamour rule
for biodiversity in
forest plantations
No. of trees of the
same species
< 10% of the total
No. of trees of the
same genus < 20%
No. of trees
of the same family
< 30% of the total
Tre e 1
Tre e 2
Genus 1
Genus 2
Genus 3
Species
1
Species
2
Tre e 3

Unasylva 250, Vol. 69, 2018/1
20
also aim for an adequate age distribution
– that is, trees of a range of ages to enable
planning for tree senescence and adequate
and sequential removal and replacement
of dead or dying trees.
Planting
Adequate tree-planting practices are essen-
tial for meeting urban and peri-urban forest
objectives, and preparation of the planting
site is also crucial: it is better to plant a
tree that costs 1 euro in a hole that costs
50 euro than a 50-euro tree in a 1-euro
hole. Several examples exist of planting
systems customized to local needs; the
City of Stockholm, Sweden, for example,
employs a hybrid system for the sustain-
able management of stormwater (Box 1).
Engineering approaches, such as the use
of cells and oating soils, can help achieve
consistent results in varying conditions
(Urban, 2008; TDAG, 2014).
A study in the United States of America
using the i-Tree model conducted a cost–
benet life-cycle analysis of 1 million
trees over a 50-year period (MacDonagh,
2015). The two treatments were: 1) urban
trees planted using a modern technique
in which the pavement is suspended over
adequate uncompacted soil volume, giving
trees a lifespan of more than 50 years; and
2) urban trees planted with insufcient
uncompacted soil volume, in which the
trees have an estimated lifespan of only
13 years and therefore need to be replaced
three times over the 50-year period and
will die before they grow sufciently
large to provide signicant ecological and
nancial benets. The study projected
that, after 50 years, the rst treatment
generated a net prot of USD 25 billion
(i.e. USD 25 000 per tree; Kestrel Design
Group, 2011), while the second resulted
in a net cost of USD 3 billion (Table 2;
MacDonagh, 2015). This nding is con-
sistent with other research, such as that
of Fowler (2011). Thus, although the
initial cost of best-practice planting may
be relatively high, the long-term benets
are immense. Planting many trees is good,
but decisions on the methods used will
largely determine the long-term costs
and benets.
UPF knowledge and management tech-
niques continue to improve, but major
gaps remain and, in most countries, there
is a lack of awareness and knowledge
among urban designers. The best way to
bridge such gaps in urban development
and management is in multidisciplinary
teams – because green infrastructure
is multifunctional and cuts across all
urban sectors.
Box 1
The Stockholm system for stormwater management
The City of Stockholm uses large stones (“large-stone skeleton soils”) to provide a high-quality
environment for tree roots that improves tree growth in urban environments and encourages
stormwater inltration and effective gas exchange. The technique involves forming a wide base
of large (100–150 mm) angular stones covered with an aeration layer (washed granite stones
63–90 mm in size). A surface layer suitable for vehicles or pedestrians, and its subgrade, is
installed over a geotextile layer placed on top of the aeration layer.
The Stockholm system pr ioritizes aboveground/belowground gas exchange and voids in the
growing medium over the abundant provision of loam soil. It enables a high degree of water
inltration while enhancing the effectiveness of aeration (water expels any carbon dioxide
built up in the voids, thereby avoiding the risk of root poisoning). Through condensation, the
aeration layer offers better moisture retention in the warm season.
The Stockholm system continues to be studied; a recent development is the use of biochar
as a lter for pollutants and to better retain nutrients and water.
Benets of the Stockholm system
• The substrate has high load-bearing capacity, including resistance to lateral forces
(e.g. heavy vehicular trafc).
• The system uses similar construction practices to those used in the industry, facilitating
its incorporation in the construction sector.
• The system can be implemented for existing trees, including mature trees.
• Tree growth rates are very high – but the system needs more study because it has been
in place for less than ten years.
Limitations of the Stockholm system
• Installation costs are high.
• Existing soil is not reused.
• The system is not technically complicated, but it requires rigorous implementation.
Sou rce: City of Stockholm, 2009.
TABLE 2. Calculation of benets and costs for tree life cycles, 1 million trees,
with inadequate and adequate planting
Inadequate planting Adequate planting
Benet after 50 years USD 2.718 billion USD 41.769 billion
Cost after 50 years USD 5.812 billion USD 16.342 billion
Life-cycle net benet (cost) after
50 years
(USD 3.064 billion) USD 25.427 billion
Investment return after 50 years -47% 250%
Value after 50 years USD 3.064 billion USD 25.427 billion
Sou rce: MacDonagh, 2015.

21
Unasylva 250, Vol. 69, 2018/1
CONCLUSION
Urban and peri-urban forests are the most
important components of green infra-
structure, providing landscape solutions
for several urban problems, including
climate change. It is essential that UPF
science, practice and technologies continue
to develop. Multiscalar, multidisciplinary,
long-term planning is key to optimizing
the advantages and ecosystem services of
UPF and for guaranteeing solutions that
meet the specic needs of a given city
and its social and demographic context,
provide equitable access, and ensure envi-
ronmental justice. It is imperative that tree
species are selected to ensure adequate
biodiversity, appropriately sized trees, the
maintenance of ecosystem functions, and
affordable maintenance. Planting systems
should be used that guarantee and leverage
ecosystem benets throughout tree life
cycles. Contemporary UPF approaches are
being applied in various contexts world
-
wide, and regulatory frameworks have
been developed to integrate and design
urban and peri-urban forest experiences
and achieve multiple purposes. Ultimately,
UPF is a socially acceptable, politically
effective, economically efcient and thus
sustainable tool. u
References
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Castel-Branco, C., Simson, A. &
Olsen, I.A. 2005. Design of urban forests.
In: C. Kon ijnendijk, K. Nilsson, T. Randr up
& J. Schipperijn, eds. Urban forests and
trees. Berlin, Springer.
City of Stockholm. 20 09. Planting beds in
the City of Stockholm. Stockholm (also
available at http://foretag.stockholm.se/
PageFiles/192562/100322%20GH_HB%20
STHLM%20-%20Engelsk%20version.pdf).
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canopy coverage in Phoenix by 2030.
Unpublished master’s thesis on landscape
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K. Nilsson, eds. COST Action E12: urban
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returns for healthy urban trees: lifecycle
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or-nightmare
McPherson, E .G., Simpson, J.R. , Peper, P. J.,
Xiao, Q., Maco, S.E., Hoefer, P.J. &
Davis, D. 2003. Northern mountain and
prairie community tree guide: benets, costs
and strategic planting. Albany, USA, Pacic
Southwest Research Station, United States
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2011. Forests, trees and human health and
well-being: introduction. In: K. Nilsson,
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K. Seeland & J. Schipperijn, eds. Forests,
trees and human health. Dordrecht, the
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Sánchez, M. et al . 2017. Social and envi-
ronmental justice: diversity in access to and
benets from urban green infrastructure.
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S. Krajter Ostoić, G. Sanesi & R.A. del Amo,
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sense. Proceedings of the 7th Conference of
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Unasylva 250, Vol. 69, 2018/1
22
Forests in cities produce goods
and generate ecosystem services
that improve the well-being of
citizens and increase the resilience
of cities to shocks.
Urban and peri-urban forests provide reg-
ulating, cultural and provisioning services
that can be of both local and global impor-
tance. Regulating services include climate
regulation (e.g. cooling), carbon storage,
air pollution removal and ood regulation
(Dobbs, Escobedo and Zipperer, 2011).
Cultural services include natural heritage,
recreation, aesthetics, knowledge transfer
and “sense of place” (Dobbs, Escobedo
and Zipperer, 2011). Provisioning ser-
vices – which are especially relevant to
city dwellers in developing countries –
include products such as food, woodfuel,
clean water and medicines (Shackleton
et al., 2015). Urban and peri-urban forests
The benets of urban and peri-urban forestry
C. Dobbs, A.A. Eleuterio, J.D. Amaya, J. Montoya and D. Kendal
Cynnamon D obbs is a researcher at t he
Depar tment of Ecosystems and Envi ronment at
Ponticia Universidad Católica de Chile, Chile.
Ana Alice Eleuterio is P rofessor at the
Depar tment of Rural Development and Food
Securit y, Universidade Federal d a Integração
Latino-A mericana, Brazi l.
Juan David A maya is Professor at Javeriana
University, Colombia.
Juliana Montoya is a res earcher in the
Biodiversity in Urban– Regional Environment s
programme, Humboldt Institute, Colombia.
Dave Kendal is a researcher a t the School of
Ecosystem and For est Sciences, University of
Melbourne, Austra lia.
© MARÍ A DEL PILAR ARROYAVE MAYA
Above: Panoram ic view of
the ecological network of the
Valle de Aburrá, northwestern
subsector of Medellín, Colombia
U
rbanization places pressure on
adjacent natural resources in and
around cities by competing for
space and demanding products from them.
Well managed, however, these natural
resources can improve the lives of urban
dwellers by providing ecosystem services.
1
Urban and peri-urban forests comprise
all the trees and associated vegetation
found in and around cities. They occur
in a range of settings, including in man-
aged parks, natural areas (e.g. protected
areas), residential areas and informal green
spaces; along streets; and around wetlands
and water bodies.
1
Here we de ne ecosystem services as the bene-
ts derived from nature that are consumed or
enjoyed by humans, increasing t heir well-being
and exer ting positive inuences on human health
(Coutts and Hahn, 2015).

23
Unasylva 250, Vol. 69, 2018/1
also contribute to biodiversity in urban
areas (Alvey, 2006) and help build cul-
tural diversity, thereby increasing urban
resilience to environmental shocks and
stresses (Colding and Barthel, 2013). This
article explores, through case studies, the
benets that urban and peri-urban forests
can provide for citizens and discusses some
of the challenges that urban forest planners
and managers will need to accommodate
in years to come.
THE BENEFITS OF URBAN AND
PERI-URBAN FORESTS
Figure 1 provides a framework for the
role of urban and peri-urban forests in the
provision of ecosystem services, thereby
shaping the well-being of urban dwellers.
Preferences for certain ecosystem services
affect policymaking and decision mak-
ing and the value assigned to ecosystem
services, ultimately affecting the structure
and composition of the urban and peri-
urban forest estate through management
actions. All components of this framework
can inuence a city’s resilience to social
and environmental stresses and shocks
(Dobbs, Martinez-Harms and Kendal,
2017).
Forest ecosystem services
Urban and peri-urban forests in good condi-
tion perform various ecosystem functions.
Through shading and evapotranspiration,
for example, they can reduce summer day-
time temperatures by up to 6 °C (depending
on the city’s latitude; Skoulika et al., 2014).
A large tree can intercept up to 190 litres
of water in a rain event, thereby reducing
water run-off and the risk of ooding and
landslides. Urban and peri-urban forests
lter air pollution, which is deposited on
leaves, thereby acting as passive sinks
for particulate matter (Nowak, 1994);
particulate matter accumulation rates of
10–70 micrograms per cm
2
of leaf area
have been recorded (Sæbø et al., 2017).
Forest products
Urban and peri-urban forests are impor-
tant sources of wood for construction and
fuel, especially for people in developing
countries, who still rely heavily on wood
energy for cooking and heating. Urban
dwellers can also make good use of the
products of fruit trees and medicinal
plants in private and community gardens,
residential areas and streets (Fuwape and
Onyekwelu, 2011). Jamun trees (Syzygium
cumini) in public areas of New Delhi,
India, for example, produce fruits that are
sold to pedestrians and motorists (Singh,
Pandey and Chaudry, 2010).
Urban agriculture
The planting and growing of trees in
urban areas contributes to the economic
strength and multifunctionality of urban
agriculture (de Bon, Parrot and Moustier,
2010), providing sources of income and
employment opportunities. Urban food
production is not only beneficial as a
service, it also increases food availability
at the local scale, thus shortening sup-
ply chains for some products (e.g. leafy
vegetables) and thereby reducing the nega-
tive impacts associated with long supply
chains. Shorter supply chains also result
in fairer product values and lower costs
for consumers, therefore improving food
security at many levels (de Bon, Parrot
and Moustier, 2010) and contributing to
community resilience (Salbitano, Borelli
and Sanesi, 2015).
On the other hand, many cities worldwide
are experiencing major shifts in property
rights from public to privately owned lands
and an associated lack of community access
to public lands that can hinder the effective-
ness of urban agriculture in the provision of
ecosystem services (Colding and Barthel,
2013). Moreover, urban agricultural plots
can serve as sinks (e.g. as receptacles of
residential solid and organic waste) and
sources of environmental pollution, includ-
ing pesticides, herbicides and fertilizers (de
Bon, Parrot and Moustier, 2010).
Social interactions, culture
and well-being
People in urban communities can lose
contact with nature (Maller et al., 2006).
There is a trend towards people spending
1
Framework for the ecosystem
servi ces provided by u rban and
peri-urban forests
Management and
conservation
Policymaking and
decision making
Resilience
Ecosystem services
Regulating, cultural,
provisioning
Human well-being
Benets and values
Human preferences
Urban and peri-urban forests
Structure and
composition
Functions
and
processes
Landscape
Forest
Tre e
Sou rce: Adapted from Dobbs, Martinez-Harms and Kendal (2017).

Unasylva 250, Vol. 69, 2018/1
24
less time in natural areas, parks and
forests than in the past, with both adults
and children adopting more sedentary and
individualistic behaviours in preference to
group activities that use open public spaces
(Taylor and Kuo, 2006). Urban forests can
foster cultural services such as a sense of
community, place and satisfaction because
they provide spaces in which people can
come together and interact socially (de
Vries et al., 2013). People become attached
to places where they feel relaxed and
comfortable, incorporating those places
into self-identity (Stoner and Rapp, 2008).
Additionally, by spending time outdoors,
people tend to exert themselves more,
boosting their physical health (Dinnie,
Brown and Morris, 2013; Giles-Corti et al.,
2013). Urban forests also have restorative
effects and can lead to improved mental
health. For example, attention fatigue
can be ameliorated by spending time
walking in green areas (Taylor and Kuo,
2006). Exposure to nature can reduce the
symptoms of depression and the risk of
developing mental disorders (Annerstedt
et al., 2015).
Financial benets
Urban and peri-urban forests can provide
nancial benets. For example, the pres-
ence of mature trees can increase property
values by 2–15 percent, and the presence of
tree cover in a residential area can increase
real estate prices by up to 9 percent (Wolf,
2017). Trees in commercial areas can
boost shopping by providing a welcoming
environment for retail stores and shaping
consumer expectations (Wolf, 2017).
The demand for urban forest products and
ecosystem services depends on their per-
ceived importance to urban dwellers, which
can vary according to socio-economic,
cultural and political realities, psycho-
logical well-being, physical health, power
inequities, and the biophysical location of
the city (Ordóñez-Barona, 2017). Urban
forest food and fuel production, for exam-
ple, may be more important in developing
countries, especially for some groups, than
in developed countries.
Biodiversity
The role of urban and peri-urban forests
in biodiversity conservation can be sig-
nicant: data on bird presence compiled
in 54 cities and on plants in 110 cities,
for example, show that a large proportion
of taxa are native, and some are endemic
(Aronson et al., 2014). In Australia,
hundreds of threatened native species occur
in cities, many of them largely dependent
on urban habitats (Ives et al., 2016).
Biodiversity can play an important role
in increasing the resilience of urban forests
to external shocks and stressors, such as
climate change (Gomez-Baggethun et al.,
2013). Diversity is needed at different taxo-
nomic levels (Kendal, Dobbs and Lohr,
2014). For example:
•
Genetic diversity contributes to resis-
tance to pests and diseases.
•
Species diversity ensures a variety
of functions (to provide multiple
ecosystem services) and functional
redundancy (to minimize the risk of
loss of particular services).
• Genus and family diversity can help
reduce the incidence of particular
pests and diseases (e.g. emerald ash
borer and myrtle rust).
•
Age diversity should be maintained
in urban and peri-urban forests to
maintain the provision of ecosystem
services over time and to reduce the
risk of uniform senescence of large
areas of forest.
•
Structural diversity (that is, the diver-
sity of tree species, vegetation strata
and density) is important for promot-
ing fauna conservation in cities by
increasing the number and complexity
of habitats (Lindenmayer, Franklin
and Fischer, 2006).
CASE STUDIES OF URBAN AND
PERI-URBAN FORESTS
A growing body of evidence from North
America, Europe, the Global South and
elsewhere corroborates the contribu-
tions of urban and peri-urban forests to
the well-being of urban dwellers. Local
governments are increasingly including
urban and peri-urban forests in their deci-
sion making, planning and regulations,
both formally and informally. Here we
provide examples of cities in which for-
estry is becoming a mainstream option for
creating sustainable and resilient cities.
Providing ecosystem services
in Colombia
Various Colombian cities have developed
explicit greening actions in recent years,
and studies have shown the benets of
urban and peri-urban forests. In the Aburrá
metropolitan area, it was estimated that
urban trees save 6 712 megagrams of car-
bon dioxide emissions per year (MgCO
2
/yr)
– equivalent to the yearly emissions of 1 428
average petrol-engine cars – by avoiding
the emission of 5 090 MgCO
2
/yr due to
savings in electric cooling and sequestering
2 077 MgCO
2
/yr (Reynolds et al., 2017). In
Medellín, large urban and peri-urban trees
represent only 1.33 percent of the total tree
population but sequester more than 25 per-
cent of carbon emitted annually in the city
and remove almost 10 tonnes of particulate
pollution (Restrepo et al., 2016). Research
on the cultural and economic benets of
urban and peri-urban forests shows that
80 percent of residents in Bogotá, Cali
and Pereira are interested in interacting
with nature (Ordóñez-Barona and Duinker,
2014). Bogotá residents also perceive that
urban forests provide other positive ser-
vices, such as shading and temperature
regulation (Rojas, 2013). Using spatial
econometric techniques, Carriazo and
Tovar (2016) found a signicant positive
relationship between the presence of urban
forests and a reduction in theft, suggesting
that psychological precursors of violent
behaviours, such as mental fatigue, could
be lower in urban populations with greater
contact with nature (Kuo and Sullivan,
2001).
This accumulated knowledge and
information has been incorporated into
policies in Colombia. A partnership
between the Humboldt Institute and the
Ministry of Environment and Sustainable
Development (Ministerio de Ambiente y

25
Unasylva 250, Vol. 69, 2018/1
Desarrollo Sostenible) has produced strat-
egies and management tools to facilitate
land planning, leading to an increase in
social connectedness with urban and peri-
urban forests and in the success of policy
implementation (Montoya et al., 2017).
Tackling climate change with urban
and peri-urban forests in Los Angeles
Los Angeles, in the United States of
America, is highly vulnerable to the
impacts of climate change, such as
increases in the frequency and severity
of ooding, drought and wildre. People
living under social constraints are most
vulnerable to the consequences of such
events. TreePeople,
2
a not-for-profit
organization, has developed a long-term
programme called The Urban Forest
Initiative with the aim of involving
local communities in increasing canopy
cover and building resilience to climate
change. Actions include planting and car-
ing for trees; supporting residential and
neighbourhood strategies for rainwater
collection; and restoring forests in depleted
areas. The ten-year goal of the initiative
is to increase canopy cover in the city by
25 percent, reduce inequities in forest dis-
tribution, and source at least 50 percent of
the water supply locally. The initiative also
intends to supply information and to work
with all levels of government to create
progressive policies for the use of urban
and peri-urban forests, changing laws and
regulations where necessary.
Recognizing the benets:
Open Tree Map
Recognizing the benets of urban and
peri-urban forests, a number of cities in
the United States of America have made
information on the location, species and
care of urban trees available to the local
and global communities using the Open
Tree Map platform,
3
which can also be
deployed to create future scenarios for
tree populations. Several local govern-
ments are using Open Tree Map to manage
and communicate information on their
urban and peri-urban forests and as a
decision-making tool to help deliver eco-
system services and create a pathway to
sustainability.
© ÁREA ME TROPOLITANA, VALLE DE ABUR RÁ
An aerial view of
El Poblado Pa rk,
Aburrá, Colombia,
where urban trees
store large amounts
of carbon and
provide residents
with shade and other
ecosystem services
2 www.treepeople.org 3 www.opentreemap.org

Unasylva 250, Vol. 69, 2018/1
26
Increasing participation for
integrated urban planning
In Foz do Iguaçu, Brazil, researchers at
the Federal University of Latin American
Integration (Universidade Federal da
Integração Latino-Americana) have
mapped urban and peri-urban forests as
part of a federally supported regional
initiative on the management and conser-
vation of Atlantic forests. The framework
generated by this initiative, the Atlantic
Forest Municipal Plan, provides informa-
tion on the state of urban natural areas.
In addition to mapping, the plan includes
environmental perception studies, risk
assessment and scenario analysis; it
also involves diverse stakeholders. The
aims of the plan are to increase public
participation in decision making and to
establish strategies for integrating urban
planning and environmental conservation.
Other university-supported projects have
investigated other benets of urban and
peri-urban forests, such as their role in
shaping children’s perceptions of socio-
ecological systems. In that project, children
participate in eld trips to urban gardens
and natural areas within their neighbour-
hoods and interview elderly residents about
local environmental history. These activi-
ties help the children develop social skills
and increase their environmental aware-
ness, and they expose children to local
arrangements in the use and conservation
of private and community green areas.
Planning with urban and
peri-urban forests
The City of Melbourne, Australia, has
changed its management of urban for-
ests in line with the challenges it faces:
climate change, population growth and
increasing urban heat. Recognizing that
a healthy forest is crucial for maintaining
the well-being of people, the City devel-
oped an urban forest strategy aligned with
its climate adaptation and open-space
strategies (City of Melbourne, undated).
The image below is a visualization of the
City’s urban forests of the future, in which
trees are present in streets and parks and
on rooftops. City planners used participa-
tory methods – strong communication and
engagement, including online visualization
and a popular “email a tree” function –
to involve residents and commuters in
establishing a clear vision and goals for the
City’s urban forests. The strategy is being
implemented through ten precinct plans,
© CITY OF ME LBOURNE
A visualization of the future
urban fore sts in the City of
Melbourne, Australia

27
Unasylva 250, Vol. 69, 2018/1
which put the principles of the strategy
into practice while integrating community
views. Complementing this, and recogniz-
ing the importance of the community in
generating and transferring knowledge,
the City of Melbourne created the Citizen
Forester Program, under which citizens are
enlisted to collect data on, among other
things, trees, tree genetics, habitats and
pollinators. Recently, the City created the
Urban Forest Fund, which, in partnership
with the private sector, unlocks nancial
support to deliver more greening on private
properties and therefore more benets for
the community.
FUTURE DIRECTIONS
Of the many challenges facing urban and
peri-urban forests and their management,
climate change, population growth and
social inequalities are the most widespread
and locally important.
Climate change
Climate change increases the risks to
urban and peri-urban forests, which must
be capable of surviving extended periods
of severe drought and extreme heat and
rain events. Urban forest plans must
reduce the likelihood of catastrophic tree
losses due to pests and diseases (Dobbs,
Martinez-Harms and Kendal, 2017).
Approaches to tree planting and landscape
design based on ornamental features and
historical performance will not necessar-
ily work in the future; rather, species will
need to be selected for the probable future
climate. Creating a genetically and func-
tionally diverse pool of species in cities
will be crucial for ensuring resilience to
climate change (Kendal, Dobbs and Lohr,
2014) and the maintenance of vital eco-
system services (Dobbs, Martinez-Harms
and Kendal, 2017).
Population growth
It has been estimated that, globally, urban
areas will have expanded by 185 percent
by 2030 compared with circa 2000, espe-
cially in China, India and other Asian
countries (Seto, Güneralp and Hutyra,
2012). Demand for food and other eco-
system services will increase worldwide
as populations grow. Urban expansion will
affect biodiversity hotspots, such as the
Eastern Afromontane, the Guinean Forests
of West Africa, and the Sri Lanka hotspots
(Seto, Güneralp and Hutyra, 2012). Urban
and peri-urban forests can be thought of
as green networks that can connect rural
and urban areas, parks and other natural
areas in and around cities. Such forests
can enable fauna mobility and increase
people’s connection with nature – requir-
ing urban planning initiatives and policies
that operate at several scales and involve
diverse stakeholders. Planning needs
to become a multidisciplinary process,
involving not only a range of government
institutions but also the communities who
inhabit the cities.
Social inequalities
Social inequalities affect access to, and
the distribution of, ecosystem services.
This is especially relevant in cities in less-
developed regions, such as Latin America.
Therefore, management strategies and
policy decisions that address only the eco-
logical dimension of ecosystem services
may increase socio-ecological vulner-
ability (Laterra et al., 2016).
Creating institutional spaces to allow the
blooming of local governance processes
for urban and peri-urban forests, involving
social networks of people of various ages,
genders, ethnicities, socio-economic back-
grounds, education and values, is essential
for building resilient communities. Civic
participation is likely to lead to innovative
actions adjusted to local realities that cre-
ate and sustain long-term linkages between
cultural and biological diversity.
Understanding the socio-ecological
context of urban forests
To develop sustainable and resilient cities,
it is necessary to understand the contexts in
which these urban dynamics occur. Urban
and peri-urban forests will not succeed by
simply copying what other cities are doing;
plans and management must be adjusted
according to the needs of individual cit-
ies, as determined by their biophysical
contexts and the values and preferences
of their communities. Planning urban
and peri-urban forests that contribute to
the sustainability and resilience of cities
requires a multidisciplinary approach in
which planners, urban designers, landscape
architects, urban foresters, engineers, park
managers and communities work together
to develop effective policies, management
regimes and regulations. The extent to
which communities are involved in the
policymaking process will be a determi-
nant of the success of urban and peri-urban
forest policies because community support
is essential, in the long term, for successful
implementation.
Access to data on the quality, quantity
and distribution of urban and peri-urban
forests is another prerequisite for
successful planning and management.
Policies must incorporate both scientic
knowledge and people’s preferences and
values. Finally, a monitoring system is
needed to evaluate the implementation of
policies; citizen science programmes are a
promising measure for obtaining ongoing
information on the status of urban and
peri-urban forests and for communicating
with and educating citizens. u
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30
Methods for estimating the
costs and benets of urban and
peri-urban forests are increasingly
accurate and easy to apply. U
rban and peri-urban forests
produce numerous benets for
society. These include moderating
the climate; reducing energy use in build-
ings; sequestering atmospheric carbon
dioxide; improving air and water quality;
mitigating rainfall run-off and ooding;
providing an aesthetic environment and
recreational opportunities; enhancing
human health and social well-being; and
lowering noise impacts (Dwyer et al.,
1992; Nowak and Dwyer, 2007; Dobbs,
Martinez-Harms and Kendal, 2017).
Inappropriate landscape design, tree selec-
tion and tree maintenance, however, can
increase environmental costs (e.g. through
pollen production and chemical emissions
that contribute to air pollution), energy use
in buildings, waste disposal, infrastruc-
ture repair, and water consumption. These
potential costs must be weighed against the
benets when developing natural resource
management programmes.
To sustain or enhance the benets of
urban and peri-urban forests for society,
it is important to understand the exist-
ing forest structure, how this structure
affects the magnitude of the benets and
costs, and how the forest structure and
therefore benets change over time. With
such understanding, managers can guide
forest structure to maximize benets for
society. Signicant advances have been
made in recent years on urban and peri-
urban forest monitoring and assessment
Improving city forests through assessment,
modelling and monitoring
D. J. Nowak
David J. Nowak is at the United St ates Forest
Service in Syracuse, New York, United States
of America.
© DAVID LORENZ WI NSTON/UNITE D STATES FOREST SERVICE
Above: The monito ring and assessment
of urban and peri-urban forests enables
the development of management plans
that optimize forest structure and the
benets s uch forests provide

31
Unasylva 250, Vol. 69, 2018/1
and in quantifying the benets and costs
associated with the resource. Many of
the benets are not easily measured in
the eld, and modelling techniques must
therefore be used to estimate their magni-
tude. This article provides an overview
of a four-step process for easily assess-
ing, modelling and monitoring urban and
peri-urban forest structure and benets.
Through this process, local management
plans can be developed that optimize forest
structure to enhance the health and well-
being of current and future generations.
STEP 1: ASSESSING FOREST
STRUCTURE
Forest structure is a key variable because
it is what managers manipulate to inu-
ence forest benets and values. Structure
represents the physical attributes of the
forest, such as the abundance, size, species,
health and location of trees. Managers
often choose what species to plant, where
and when to plant them, and what trees
are removed from the landscape. These
actions directly inuence structure and
consequently the benets derived from
the urban and peri-urban forest resource.
Bottom-up or top-down?
There are two basic ways of quantifying
structure in urban and peri-urban forests:
1) top-down aerially based approaches; and
2) bottom-up ground-based assessments.
Top-down assessments provide basic
metrics on tree cover (e.g. percentage tree
cover) and other cover types, and they can
map the specic locations of such elements.
Tree cover can often be estimated
by interpreting aerial photographs or
by developing tree-cover maps using
moderate-to-high-resolution imagery
(e.g. Nowak, 2012a). If only the amount
or percentage of tree cover is needed, photo
interpretation provides a cost-effective and
accurate means of assessing tree and other
cover attributes; it lacks specic informa-
tion on cover location, however.
If cover locations are needed, tree-cover
maps can provide both tree-cover estimates
and specic locations of cover elements
(e.g. to be integrated into a geographic
information system). Tree cover and distri-
bution are important parameters of urban
and peri-urban forest structure because
they provide a simple way of conveying
the magnitude and distribution of the
forest resource. More detailed data on
forest structure (e.g. species composi-
tion, the number of trees, tree size, tree
condition, leaf area, leaf biomass and tree
biomass) are often needed, however, to
© DAVID LORENZ WI NSTON/UNITE D STATES FOREST SERVICE
Healthy tree leaves are crucial for
the provision of many of the benets
of urban and peri-urban forests

Unasylva 250, Vol. 69, 2018/1
32
assess the benets and costs and to guide
management. Although various aerially
based approaches are being researched and
developed to derive specic tree informa-
tion, the best existing approach for deriving
many tree variables is eld measurement.
Field data on urban and peri-urban forest
structure can be obtained from inventories
or by sampling. For large tree populations,
eld data in conjunction with aerially
based assessments will likely provide the
best and most cost-effective means for
assessing urban and peri-urban structure.
The most important parameters are spe-
cies, diameter, crown dimensions, and tree
condition. This information is helpful to
managers for population management and
in assessing risks to the resource, and it
is also essential for estimating benets
and costs.
Attributes for modelling
For most benets, the most important
tree attribute is leaf area. Although not
directly measured in the eld, this vari-
able can be modelled from information on
species, crown size and crown condition,
while diameter measures are essential for
estimating carbon storage. Leaf and tree
biomass can be modelled from these core
tree variables. Other important attributes
for estimating urban and peri-urban forest
benets are crown competition (important
for estimating tree growth and carbon
sequestration) and location around build-
ings (important for estimating energy
conservation). Numerous benets of urban
and peri-urban forests can be modelled
from these tree variables, in conjunc-
tion with other local information (e.g. on
weather, pollution and demographics).
There is interdependence between urban
and peri-urban forest structure, benets
and economic valuation. Valuation is
dependent on good estimates of the
magnitude of the benet provided, and
benet estimates require good estimates
of forest structure and how it affects
benets. Benets and values cannot be
adequately quantied without good data
on forest structure. Combining accurate
data with sound procedures for quantifying
benets will produce reliable estimates
of the magnitude of benets provided by
urban and peri-urban forests. With these,
the value of benets can be estimated using
valid economic estimates and procedures.
Thus, three crucial elements are needed in
sequence to value the benets of urban and
peri-urban forests and to aid their man-
agement: structure  benets  values.
Errors with precursor elements will lead to
errors in subsequent estimates (e.g. errors
in forest structure will lead to errors in
estimating benets and values).
STEP 2: MODELLING URBAN AND
PERI-URBAN FOREST BENEFITS,
COSTS AND VALUES
Information on forest structure can aid
managers by revealing species composi
-
tion, sizes, locations and potential forest
risks (e.g. species composition can reveal
potential risks posed by insects and
disease infestations). Understanding the
links between urban and peri-urban forest
structure and the benets those forests
provide is essential for optimizing the
benets through management. Because
many benets cannot be measured easily
in the eld (e.g. air pollution removal),
UNIT ED STATES FOREST SERVICE
A colour-enhanced
aerial image of
New York City,
United States of
America . The structure
and benets of
urban and p eri-urban
forests var y across
landscapes as forest
cover and hum an
populations vary

33
Unasylva 250, Vol. 69, 2018/1
models are used to estimate benets, costs
and values based in part on the measured
data on forest structure. Once the benets
have been quantied, various methods of
market and non-market valuation can be
applied to characterize their monetary
value (e.g. Hayden, 1989).
Various models exist for quantifying
forest benets; freely available models
include InVEST (Natural Capital Project,
undated), Biome-BGC (Numerical
Terradynamic Simulation Group, undated)
and numerous tools for assessing forest
carbon (e.g. United States Forest Service,
2016a). Few models quantify urban and
peri-urban forests, however. The most
comprehensive model developed to date
for quantifying urban and peri-urban
forest structure, benets and values is
i-Tree,
1
a freely available suite of tools
developed by the United States Forest
Service through a public–private part-
nership. i-Tree is based on peer-reviewed
science and can be used globally, and it
has more than 180 000 users in 130 coun-
tries; it was designed to accurately assess
local forest structure and its impacts on
benets, costs and values (Table 1). Model
results have been validated against eld
measurements (e.g. Morani et al., 2014) to
provide sound estimates of the benets of
urban and peri-urban forests. The model
focuses on estimating forest structure and
the magnitude of services received (e.g.
tonnes of carbon removed). It then relies on
economic valuation (e.g. dollars per tonne
removed) to estimate the value of a given
service. The model uses various economic
estimates; users can adjust many of these if
local economic values are available.
i-Tree Eco
The core programme of the i-Tree suite is
i-Tree Eco. This model, which can be used
globally, uses sample or inventory data and
local environmental data to assess and
forecast forest structure, benets, threats
and values for any tree population (Nowak
et al., 2008). i-Tree Eco includes plot
selection tools; mobile data entry appli-
cations; tabular and graphic reporting and
exporting; and automatic report genera-
tion. Assessments of urban and peri-urban
forests have been conducted using this
model in numerous cities globally, includ-
ing Barcelona, Spain; Calles, Mexico;
Chicago, United States of America;
London, United Kingdom of Great Britain
and Northern Ireland; Medellín, Colombia;
Milan, Italy; New York, United States of
America; Perth, Australia; Porto, Portugal;
Santiago, Chile; Seoul, Republic of Korea;
Strasbourg, France; and Toronto, Canada
(Chaparro and Terradas, 2009; Escobedo
et al., 2006; Graca et al., 2017; Nowak
et al., 2007, 2010, 2013; Rogers et al., 2015;
Selmi et al., 2016).
The other tools in i-Tree are:
•
i-Tree Species – selects the most
appropriate tree species based on
desired environmental functions and
geographic area;
• i-Tree Hydro – simulates the effects
of changes in tree cover and impervi-
ous cover on run-off, stream ow and
water quality;
•
i-Tree Canopy* – allows users to
easily photo-interpret Google aerial
images to produce statistical estimates
1 www.itreetools.org
TABLE 1. Benets and costs of trees currently quantied and in development
in i-Tree
Ecosystem effect Attribute Quantied Valued
Atmosphere
Air temperature  
Avoided emissions  
Building energy use  
Carbon sequestration  
Carbon storage  
Human comfort 
Pollen 
Pollution removal  
Transpiration 
Ultraviolet radiation 
Volatile organic compound emissions 
Community/social
Aesthetics/property value  
Food/medicine 
Health index1
Forest products2 
Underserved areas 
Terrestrial Biodiversity 
Invasive plants 
Nutrient cycling 
Wildlife habitat 
Water Avoided run-off  
Flooding  
Rainfall interception 
Water quality 
Not es:  = attribute currently quantied or valued in i-Tree;  = attribute in development in i-Tree;
1 = developing a health index based on mapping of green viewing (“forest bathing”); 2 = estimating product
potential based on forest structure (e.g. timber, wood pellets, ethanol).
Sou rce: Nowak (2017).

Unasylva 250, Vol. 69, 2018/1
34
of land-cover types. Historical imagery
in Google Earth can also be used in
analysing changes in land-cover types;
•
i-Tree Design – links to Google Maps
and enables users to quantify the cur
-
rent and future benets of trees on
their properties;
•
MyTree – easily assesses the benets
of one to a few trees using a phone via
a mobile web browser; and
• i-Tree Landscape – allows users to
explore tree canopy, land cover, tree
benets, forest and health risks, and
basic demographic information any-
where in the United States of America
and to prioritize areas for tree planting
and protection.
i-Tree is being developed through a col-
laborative effort among numerous partners
to better understand and quantify how
changes in forest structure will affect
benets and values and to aid in urban and
peri-urban forest management and plan-
ning. Many new forest benets and costs
are being added to the model (Table 1).
Assessments and modelling in the
United States of America indicate that
there are an estimated 5.5 billion trees
(39.4 percent tree cover) in urban areas
nationally, containing 51.5 million hec-
tares of leaf area and 40 million tonnes of
dry-weight leaf biomass. Annually, these
trees produce a total of USD 18.3 billion
in value, comprising air pollution removal
(USD 5.4 billion), reduced building energy
use (USD 5.4 billion), carbon sequestration
(USD 4.8 billion) and avoided pollutant
emissions (USD 2.7 billion) (Nowak and
Greeneld, in press).
STEP 3: DEVELOPING
MANAGEMENT PLANS
Urban and peri-urban forests change
constantly, and the goal of management
is to guide such forests towards desirable
outcomes that maximize benets for pres-
ent and future generations. A crucial step
towards achieving this goal is to develop an
urban and peri-urban forest management
plan that optimizes forest structure over
time. Data from local assessments and
modelling, in conjunction with inputs from
residents, can be used to develop plans to
sustain or enhance urban and peri-urban
forest structure and benets. These plans
can be as simple as detailing the means
(e.g. funding) for attaining desired tree-
cover goals at specic locations, or they
can provide detailed information on plant-
ing rates by species and location.
© DAVID NOWAK
A tree- lined street in H onolulu, Hawaii ,
United States of America. The design
of urban and peri-urban forests is
important for minimizing potential
negative ef fects, such as trapping
pollutants near roadways

35
Unasylva 250, Vol. 69, 2018/1
Urban tree cover is on the decline in the
United States of America (Nowak and
Greenfield, 2012). Management plans
need to consider various forces that are
likely to alter forest structure over time,
including forces that decrease tree cover
(e.g. development, storms, insects and
diseases, and old age) and increase tree
cover (e.g. tree planting, natural regenera-
tion and invasive species). In the United
States of America, it is estimated that two-
thirds of the existing urban forest is from
natural regeneration (Nowak, 2012b). The
inuence of tree planting tends to increase
in cities in grassland and desert areas, in
more densely populated cities, and on land
uses that are highly managed in relation to
trees (e.g. residential lands). Planning for
both human- and nature-driven changes in
urban and peri-urban forests will facilitate
better management plans that can sustain
forest structure and benets over time.
STEP 4: MONITORING CHANGE IN
URBAN AND PERI-URBAN FORESTS
The last step in the assessment process is
to remeasure the forest periodically (i.e.
monitoring) to determine how it is chang-
ing and whether management goals are
being met. This step is a remeasurement of
the forest structure, as conducted in step 1,
thereby restarting the cycle of modelling
benets and evaluating or updating man-
agement plans (Figure 1). The evaluation
cycle (e.g. every 5–10 years) can ensure that
the structure of the urban and peri-urban
forest is progressing in the desired fashion
to sustain benets and values for society.
An increasing number of cities globally
are assessing their urban and peri-urban
forests so as to better understand the
benets and costs. The United States Forest
Service Forest Inventory and Analysis pro-
gramme, in partnership with states and
cities, is undertaking long-term urban forest
monitoring in the United States of America.
This programme collects urban forest data
annually to assess forest structure, benets
and values and changes in these over time.
The rst city to complete a baseline assess-
ment was Austin, Texas (Nowak et al.,
2016); 26 cities were monitored in 2017, and
new cities will be added to the monitoring
programme over the next few years (United
States Forest Service, 2016b).
KEY FINDINGS
The main points made in this article can
be summarized as follows:
•
Understanding and accounting for the
benets provided by urban and peri-
urban forests enables better planning,
design and economic decisions for
using those forests to improve envi-
ronmental quality and human health
and well-being.
• Data on urban and peri-urban forest
structure (e.g. species composition
and tree locations), and how that struc-
ture affects benets and values, are
crucial for such improvement.
•
i-Tree is a simple and freely available
set of tools for assessing and valu-
ing the impact of trees and forests –
from the scale of local forest parcels
to regional landscapes – on environ-
mental quality and human health and
well-being.
•
Monitoring urban and peri-urban
forests is crucial for assessing change
and evaluating management plans.
The United States of America has
recently begun a national urban for-
est monitoring programme in several
cities and states.
• Future assessments, monitoring and
management plans can help lower
costs and sustain the benets of urban
and peri-urban forests. u
Disclaimer: The use of trade names in this
article is for the information and conveni-
ence of readers. Such use does not constitute
official endorsement or approval by the
United States Department of Agriculture
or the United States Forest Service of any
product or service to the exclusion of others
that may be suitable.
1
Cycle of ur ban and peri-ur ban forest
assess ments and monitor ing for
sustaining forest bene ts over time
Model benets
and costs
Develop/implement
urban and
peri-urban forest
management plan
Assess forest
structure

Unasylva 250, Vol. 69, 2018/1
36
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37
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Demand for forests and other
green spaces is leading to new
models of urban governance. Trees, woodlands and other vegeta-
tion make crucial contributions to
the health, well-being and resil-
ience of urban communities. A body of
evidence has accumulated in recent years
on, for example, the roles of urban forests
in mitigating the impacts of climate change
and urban “heat islands” (Roy and Byrne,
2014; Dobbs, Martinez-Harms and Kendal,
2017), and the case has also become strong
for urban forests and other green spaces
as important contributors to public health
(e.g. van den Bosch, 2017). Urban forests
are often under pressure, however, from
development and urban densication, poor
management and their low political status
(Haaland and Konijnendijk van den Bosch,
2015).
Better urban and peri-urban forestry
(UPF) programmes are needed in com-
munities worldwide. The interdisciplinary
eld of UPF operates in a complex context,
with rapidly changing conditions, drivers
and “storylines” (such as biodiversity loss,
and the need to adapt cities to climate
change and to enhance public health), and
many issues compete for the attention of
decision makers and local communities
(Sheppard et al., 2017).
The changing governance of urban forests
C.C. Konijnendijk, P. Rodbell, F. Salbitano, K. Sayers, S. Jiménez Villarpando and M. Yokohari
Cecil C. Konijnendijk van den Bosch is Professor
of Urban Forestry at the University of British
Columbia, Canada.
Phillip Rodbell is Urban and Community Forestry
Program Leader, United States Forest Service,
Northeastern Area, United States of America.
Fabio Salbitano is Associate Professor at t he
University of Florence, Italy, and a regular advisor to
FAO’s urban and peri-u rban forestry prog ramme.
Kevin Sayers is Program Coordinator for Urban and
Community Forestry at the Michigan Department of
Natural Res ources, United States of Am erica.
Sarah Jiménez Villarpando is an urban forester
working in Cochabamba, Bolivia (Plurinational
State of).
Makoto Yokohari is Professor of Landscape
Planning at the University of Tokyo, Japan.
© THE GRE ENING OF DETROIT
Local action organized by
The Greening of Detroit in Mic higan,
with seed funding from the fed eral and
state governments, is a governance
model that has built a constituency
for city fore st management across the
United States of America

Unasylva 250, Vol. 69, 2018/1
38
An expanding global urban forestry
community, and increasing networking
and knowledge exchange supported by
organizations such as FAO, has resulted in
greater knowledge and acceptance of good
practices in urban forest design, planning
and management. To date, however, only
limited attention has been given to the
way in which decisions on urban forests
are made at the strategic level. Who is
involved in such decisions, and who is
left out? What are the main storylines?
How is decision making organized, and
who takes the lead? All these questions
need attention.
From education to governance
Traditionally, UPF professionals have
focused efforts on educating politicians
and raising citizen awareness about the
importance of urban trees and wood-
lands. We have come to realize, however,
that UPF needs to move beyond this to
find ways of including a wider set of
stakeholders in decision making and
management (Sheppard et al., 2017).
In forestry in general, there is grow-
ing interest in emerging, often complex
multi-actor decision making – processes
captured in the concept of “governance”.
Previously, public actors such as state
forest authorities tended to dominate
forest policy, planning and manage-
ment, but this is less the case today. In
UPF, municipal forestry and parks (or
planning and engineering) departments
still play leading roles, but increasingly
they must involve other actors. Thus, we
can see a movement from governance
by government to governance with (and
sometimes even without) government
(Konijnendijk van den Bosch, 2014).
Denitions of governance vary widely.
All recognize, however, a strategic shift in
which a range of government actors share
(or transfer) decision making and rule
setting with (or to) civil society and busi-
nesses (Lawrence et al., 2013; Sheppard
et al., 2017). Governance involves deci-
sions, negotiation and a range of power
relations among stakeholders to determine
who gets what, when and how (UNDP,
2009).
Knowledge of urban and peri-urban for-
est governance and the different shapes
and models it can take is still limited.
Therefore, we need to study examples
of governance models across the world
and draw lessons from them. There is an
emerging body of research on urban forest
governance (e.g. Bentsen, Lindholst and
Konijnendijk, 2010; Lawrence et al., 2013;
Buizer et al., 2015; Sheppard et al., 2017),
but much more work is needed, involving,
for example, more cases from develop-
ing countries. In this article, we illustrate
the diversity of urban forest governance
using three promising examples. The rst
introduces a well-established, public-
sector-led UPF programme in the United
States of America. The second presents a
case of emerging urban forest governance
in a difcult developing-country context
in Bolivia (Plurinational State of). The
third examines an innovative govern-
ance approach in Tokyo, Japan, involving
public–private partnerships.
PUBLIC-SECTOR LEADERSHIP
AND CIVIL-SOCIETY PARTNERSHIP
IN MICHIGAN
The United States Forest Service has a
unique programme across all states and
territories of the United States of America
to support state and local governments
in improving the extent and condition
of their urban and peri-urban forests.
Authorized in 1978 and expanded in
1990 with the help of non-governmental
partners, the programme builds capacity
and strengthens local action to plant and
protect trees and forests for the economic,
social, environmental and psychological
benets they provide (United States Forest
Service, 2017).
The national programme has focused
on local governance since its inception.
Although tree planting is recognized
as an important entry-level activity that
engages people and organizations, the real
target has been local tree inventories and
management planning and the creation and
nurturing of sustainable local programmes
and institutions that protect existing tree
cover across all lands. Delivered in part-
nership with state forestry agencies, the
programme supports a network of state
coordinators and technicians in every
state and reaches more than 7 800 cities,
towns and villages serving 200 million
residents nationwide. These communities
have local laws protecting trees, and nearly
70 percent employ professional staff and
have management plans in place.
One model partnership is between
the United States Forest Service and
the Michigan Department of Natural
Resources (DNR). The state of Michigan
lies within the Great Lakes basin, sur-
rounded by the world’s largest freshwater
lake system, and the majority of the state’s
nearly 10 million residents live on roughly
11 000 km2 (13 percent of the land area).
The state concentrates its urban work in
300 communities, with an average 21 per-
cent tree canopy.
The provision of federal funds
(USD 344 000 in 2017) to the state through
the urban forest programme is driven by
a DNR forest action plan developed in
collaboration with a statewide advisory
(governing) council. The programme’s
focus is to:
• reduce threats from invasive pests;
•
build local community capacity to
manage urban forest resources;
•
maintain community quality of life
and economic resilience; and
• reforest urban and peri-urban areas.
The funding supports state technical
assistance and non-governmental partner-
ships that help deliver services and engage
a growing network of professional and
volunteer leaders. More than 50 percent of
funds are allocated in grants to local gov
-
ernment to build public- and private-sector
capacity in tree planting, tree inventory,
management planning and education and
training.
Detroit (population 711 000), in
Michigan, provides an example of how
the federal programme is delivered
locally. The city has a storied history

39
Unasylva 250, Vol. 69, 2018/1
of local park and tree investment dat-
ing back to its founding in 1701, and it
boasts 1 986 hectares of parkland in a
total area of 360 km
2
. In the mid-twentieth
century at the height of its population
(1.8 million people), the city reportedly
had 250 000 street trees; by 1990, however,
it had lost half its tree canopy to Dutch
elm disease, and thousands more trees
were subsequently lost to the emerald
ash borer. Since 2000, with DNR lead-
ership, the United States Forest Service
has supported The Greening of Detroit, a
non-governmental organization, to engage
residents in restoration planting and tree
maintenance. In 2010, the Forest Service
and DNR funded a multiyear, citywide
street-tree inventory that identied the
species and condition of 175 000 public
trees. Using i-Tree tools,
1
the inventory
collectively valued the city’s street trees at
USD 29 million; this convinced city lead-
ers to fund and implement a management
plan to address dead and dangerous trees,
diversify its tree population, and rebuild
its forestry division to conduct regular
maintenance. With a strong constituency
for trees in Detroit, the future looks bright.
The pattern is similar in other Forest
Service and state work in cities across
the country. Sustaining long-term rela-
tionships, leveraging local capacity and
investing in credible, science-based
approaches are key to creating govern-
ance and building local commitment for
successful city forest management.
COCHABAMBA: A COMMUNITY
CALLS FOR BETTER GOVERNANCE
With 630 000 residents, Cochabamba is the
fourth-largest city in Bolivia (Plurinational
State of), and it is situated at the centre of
a larger metropolitan area with 1.2 million
residents. Cochabamba’s urban population
is growing by almost 2.5 percent per year.
Located at 2 500 m above sea level on an
inter-Andean plateau, the city has a mild
climate compared with elsewhere in the
region. Because of this, it is also known as
the “Garden City” and the “City of Eternal
Spring”. Conditions in the city have
changed dramatically in the last decade,
however, due to poor urban governance and
planning, which transformed the Garden
City into a chaotic urban complex with
severe socio-environmental problems.
Many of these problems are strongly asso-
ciated with a substantial decrease in tree
and vegetation cover in both established
urban settings and new urban development
zones. The city’s environment has been
under pressure from rapid and unplanned
urban expansion. Pervious soils tradition-
ally covered by vegetation and trees have
been converted to impervious surfaces.
The few native trees remaining on public
roads, sidewalks and parks have been
replaced with exotic ones because of the
latter’s allegedly more rapid growth. The
exotic trees are declining, however, and
are not being replaced, and the loss of tree
cover has accelerated.
1 www.itreetools.org; see also article on page 30
of this issue.
© SARAH JI MÉNEZ VIL LARPANDO
Unplanned urban developm ent
is causing the deterioration of
environmental quality in Cochabamba,
Bolivia (Plurinational State of).
Pressure from a citizens’ group has
led to the development of an urban
forest strategy in the city

Unasylva 250, Vol. 69, 2018/1
40
Faced with deteriorating environmental
quality, Cochabamba residents began
expressing concern about what was hap-
pening to the city environment as well as
with the municipal administration and its
management choices. Before the approval
of the Municipal Tree Law in 2017, the
management of public green spaces was
based on a 1998 tree ordinance and on a
regulation for the protection and control
of green spaces dating from 2003. Both
these documents lacked clear legal and
administrative procedures as well as tech-
nical support for their implementation.
The weak municipal structure has been
unable to develop effective tree care and
forest management.
Facing this critical situation, in 2016
the municipal administration promoted
the preparation of an urban forest master
plan as a planning tool with a compre-
hensive vision for addressing prevailing
problems and nding solutions. The plan
denes strategic, technical, administra-
tive, normative and institutional guidelines
and criteria and sets the course for a new
model of urban forest management and
planning.
Local citizens played a crucial role in
the development of this plan by stressing
the need for better protection of exist-
ing trees and for afforestation initiatives.
Community involvement was encouraged
through a process of active tree citizen-
ship. The grassroots collective No to the
Felling of Trees (No a la tala de árboles
– “the collective”), was created in March
2016 to defend the city’s trees. Sarah
Jiménez Villarpando, an urban forester,
participated in it from the beginning, and
it soon gained popularity in social media,
reaching nationwide attention within a few
weeks and inspiring similar spontane-
ous actions in other cities. The collective
made public announcements about the
mistreatment of trees. Although apoliti-
cal, it could be considered radical, and
it was highly critical of the mayor and
especially of EMAVRA, the company
responsible for managing the city’s trees
and green spaces. Initially, the collective
was opposed to any intervention that
would harm the city’s trees and did not
want to negotiate with the mayor’s ofce.
Many members of the collective, although
passionate about trees, had only basic
knowledge about the need for the proper
management of urban trees and forests. To
address this, Sarah Jiménez and a few of
her urban-forestry colleagues conducted a
long process of education within the group.
The collective initially rejected the pro-
posed municipal urban forest master plan,
and the negotiation expanded to include
other interested parties. The process was
long and delicate, and the collective’s strat-
egy was to put pressure on the municipal
authorities while maintaining the techni-
cal content of the plan. Eventually, the
collective accepted a modied plan and
the Municipal Tree Law that followed.
The strong commitment of the citizens
and public institutions, and the common
recognition of the importance of urban
trees to the city’s future, encouraged the
© GERAR DO BRAVO BAYÀ, LOS TIEMPOS, 17 MAY 2016
Members of the
grassroots collective
“No to the Felling of
Trees” march in Plaza
14 de Septiem bre,
Cochabamba, in
May 2 016

41
Unasylva 250, Vol. 69, 2018/1
various municipal bodies to nally collab-
orate with civil society. The Municipal
Tree Law was adopted on 3 October 2017,
in tribute to the National Day of the Tree
(traditionally held on 1 October).
PUBLIC–PRIVATE PARTNERSHIPS
FOR NEW URBAN FORESTS IN TOKYO
Increasing green open spaces has been a
major challenge for many Japanese cities,
and Tokyo is no exception. Although the
western third of Tokyo is mountainous and
covered mainly by forests, only 3 percent
of the land area in the core of the city is
dedicated to green spaces. The Tokyo
Metropolitan Government and local munici-
palities in Tokyo have worked persistently
to increase public green spaces, especially
parks, but increases have mainly been in
the suburbs and there has been no major
improvement in the central area. Although
the shortage of green spaces in central
Tokyo is a major public concern, further
investment by the Tokyo Metropolitan
Government and local municipalities in
creating public green spaces cannot be
expected because of the stagnant nancial
condition of those bodies.
Meanwhile, a growing concern for envir-
onmental conservation has led real estate
developers and enterprises to contribute to
the improvement of the urban environment
as part of their corporate social responsi-
bility policies. To encourage the private
sector to participate actively in the creation
of green spaces, which can help conserve
biodiversity, improve the urban climate
and provide recreational opportunities, the
Government of Japan approved several new
regulations on building design and urban
planning. The “overall design system”,
established in the Building Standards Act,
is a good example. The aim is to improve
the quality of development projects by
providing bonus volume- or height-control
allowances to buildings on project sites
that full environmental-quality criteria
set by the government. One of the criteria
is the creation of a substantial area of
green space that is permanently open to
the public. The application of this system
has enabled the development of more than
700 green spaces in central Tokyo, includ-
ing the headquarters of Mitsui Sumitomo
Marine Insurance, which has 4 700 m
2
of green space at its base that is open to
the public.
Another prominent regulation under
the Urban Green Space Conservation
Act establishes a system for certifying the
public accessibility of privately owned
green spaces. This system encourages the
creation of green spaces for public use on
privately owned vacant lands by providing
landowners with nancial incentives such
as tax concessions. The Kashiniwa pro-
ject, established in 2012 in Kashiwa City
(near Tokyo), was used as a model for the
system: it brings together the owners of
© GOOGLE M APS
The headquarters
of Mitsui Sumitomo
Marine Insurance in
Tokyo has 4 700 m2
of publicly a ccessible
green space at its
base. A new model
of public–private
partnership is helping
create new green
space in this densely
populated city

Unasylva 250, Vol. 69, 2018/1
42
vacant land and citizens who want to create
green spaces for public use and supports
such matches by providing landowners
with nancial incentives.
In the history of open green spaces in
Japanese cities, there used to be a robust
“wall” between the public and private
realms. Public open spaces such as parks
were created only by the public sector on
publicly owned lands, and the private sec-
tor had no interest in contributing to the
creation of publicly available green spaces.
As corporate social responsibility policies
have become more integral to the activi-
ties of private enterprises, however, and
in light of the United Nations Sustainable
Development Goals, this is no longer the
case. The private sector is actively seeking
opportunities to play substantial roles in
the “public” domain. The future of open
green spaces in central Tokyo relies on such
successful public–private partnerships.
TAILOR-MADE GOVERNANCE FOR
SUCCESSFUL URBAN FORESTRY
The three cases described in this article
illustrate the wide variety of urban forest
governance approaches in place across
the world. No single model will work
everywhere: each city and urban forest
will need its own, tailor-made approach.
In Cochabamba, where good governance
was absent, it took a bottom-up initiative
by a group of concerned citizens to move
towards better urban forest governance
and laws. Many cities in the developing
world face similar conditions and lack
basic governance and urban forest pro-
grammes. When resources are limited, the
involvement of local communities and non-
prot-making organizations is essential.
Nevertheless, municipal authorities will
continue to play crucial roles, too, because
they usually have formal responsibility for
public street trees, parks and woodlands
and for city master planning. At the other
end of the spectrum, in the United States
of America, a federal government initia-
tive to support urban forestry in states and
cities has been in place since 1978. The
programme has evolved to leverage effort
and funds by means of partnerships with
states, cities and non-prot-making organi-
zations, as the case of The Greening of
Detroit illustrates. Ultimately, a top-down
governance structure has become blended
in a co-governance model in which local
communities play leading roles.
The case of Tokyo presents a third
approach to governance. There, businesses
are becoming drivers of urban forest
establishment and even governance. In
dynamic, densely populated cities such
as Tokyo, land comes at premium prices,
and retrotting the urban core with urban
forests or other green components is very
difcult for local authorities. A new avenue
towards greening can be created, however,
if businesses see benets in greening their
properties, encouraged by co-governance
in the form of public–private partnerships.
Faced with the challenge of creating
healthy living environments for their citi-
zens, cities across the world are increasingly
recognizing urban and peri-urban forests
as key components. Good governance is
required to make urban forest programmes
effective while also ensuring that the
benets are shared equitably. Learning
from the successes and failures of existing
governance approaches and models is an
important part of the process of developing
better urban forest governance. u
References
Bentsen, P., Lindholst, A.C. &
Konijnendijk, C.C. 2010. Reviewing eight
years of urban forestry and urban greening:
taking stock, looking ahead. Urban Forestry
and Urban Greening, 9(4): 273–280.
Buizer, M., Elands, B., Mattijssen, T.,
van der Jagt, A. , Ambro se , B., Ge rő házi, E.
& Møller, M.S. 2015. The governance
of urban green spaces in selected EU
cities. Deliverable 6.1, EU 7th Framework
project GREEN SURGE (also available
at: http://greensurge.eu/products/planning-
governance).
Dobbs, C., Mar tinez-Harms, M. & Kenda l, D.
2017. Ecosystem services. Chapter 4 in:
F. F er rini, C. Konijnendijk van den Bosch
& A. Fini, eds. Routledge ha ndbook of urban
fores try. Abingdon, UK, Routledge.
Haaland, C. & Konijnendijk van den Bo sch, C.
2015. Challenges and strategies for urban
green space planning in cities undergoing
densication: a review. Urban Forest ry and
Urban Greening, 14(4): 760–771.
Konijnendijk van den Bosch, C. 2014. From
government to governance: contribution to
the political ecology of urban forestry. In:
L.A. Sandberg, A. Bardekjian & S. Butt,
eds. Urban forests, trees and greenspace:
a political ecology perspective, pp. 35–46.
Abingdon, UK, Routledge.
Lawrence, A., De Vreese, R., Johnston, M.,
Sanesi, G. & Konijnendijk van den Bosch,
C.C. 2013. Urban forest governance: towards
a framework for comparing approaches.
Urban Forestry and Urban Greening, 12(4):
464–473.
Roy, S. & Byrne, J.A. 2014. A systematic
quantitative review of urban tree benets,
costs, and assessment methods across cities
in different climatic zones. Urban Forestry
and Urban Greening, 11: 351–363.
Sheppard, S., Konijnendijk van den Bosch, C.,
Croy, O., Palomo, A.M. & Barron, S. 2017.
Urban forest governance and community
engagement. In: F. Ferrini, C. Konijnendijk
van den Bosch & A. Fini, eds. Routledge
handbook of urban forestry, pp. 205–221.
Abingdon, UK, Routledge.
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governance practice. New York, USA, United
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and Community Forestry Program [online].
[Cited 5 October 2017]. www.fs.fed.us/
managing-land/urban-forests/ucf
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and long live nature! Commentary. The
Lancet Planetary Health, 1(7): e265–266. u

43
Unasylva 250, Vol. 69, 2018/1
Increasing international attention
is an opportunity to deploy
smart, green, cost-effective water
management policies in towns and
cities and their hinterlands.
T
he era of globalization is giving
rise to unprecedented trends and
patterns in the ows of humans
and natural capital. Most prominently, the
speed and magnitude of the shift from
rural to urban living are having direct
impacts on water demand and supply.
Cities might occupy only a small propor-
tion (roughly 2 percent) of the world land
area but they account for 60 percent of total
world energy consumption and 70 percent
of greenhouse gas emissions (BP, 2017). In
2014, about 54 percent of the global popula-
tion was urban; this is projected to increase
to 60 percent by 2030 and to 66 percent
by 2050 (when the total population is
projected to reach 9.55 billion) (U NDESA,
2014). Minimizing the resultant stress on
urban areas and natural capital and ensur-
ing water security will require increased
attention and smart planning.
Water security is “the capacity of a
population to safeguard sustainable access
to adequate quantities of acceptable-
quality water for sustaining livelihoods,
human well-being, and socio-economic
Forests as nature-based solutions for
ensuring urban water security
N. Nagabhatla, E. Springgay and N. Dudley
Nidhi Nagabhat la is Pr ogra mm e Of cer at th e
United Nations University Institute for Water,
Health and Environment. She is also at the School
of Geography and E arth Sciences, McMaste r
Un iver sity, Ha mi lton , Ca na da .
Elaine Springgay is Forestry Ofcer in the
Forestry Policy a nd Resources Division, Forestr y
Depar tment, FAO, Rome.
Nigel Dudley is at the School of Ea rth and
Environmental Sc iences, University of Queensland,
Brisbane, Australia. He is also a consultant with
Equilibr ium Research, Bristol, United K ingdom
of Great Brita in and Norther n Ireland.
© PREM NAGABHATLA
Visakhapatnam, Andhra Pradesh,
India, an urban centre of more than
5 million people, is preparing to
become a smart, green city. The need
for nature -based solutions to address
urban water insecurity is increasingly
apparent, here and worldwi de

Unasylva 250, Vol. 69, 2018/1
44
development, for ensuring protection
against water-borne pollution and water-
related disasters, and for preserving
ecosystems in a climate of peace and
political stability” (UN-Water, 2013).
Economic water scarcity, the deterioration
and destruction of water infrastructure,
unsustainable development and ecological
degradation are putting pressure on water-
supply systems. High population densities
and large industries mean that addressing
urban water security is a key priority.
Water security in both urban and rural
landscapes is affected by hydro-climate
dynamics (and climate change), migration
ows, demography and supply-based water
management practices. Water is at the
core of urban planning and is crucial for
socio-economic development and healthy
ecosystems; its links to the health, welfare
and productivity of populations are made
clear in many recent research and devel-
opment reports, including the UN-Water
(2013) synthesis report. Scientists sug-
gest that only about 200 000 km
3
of the
water supply – less than 1 percent of the
total available fresh water – is allocated
for ecosystems in supply-oriented water
management planning (Boberg, 2005). On
the other hand, water demand for human
consumption has almost doubled in the last
century, and the world is projected to face
a 40 percent global water decit under a
business-as-usual scenario (WWAP, 2015).
Ensuring a sustainable water supply is
crucial for the survival and sustainable
development of urban areas, and it looms
as a major global challenge in coming
years.
Nature-based solutions
Nature-based solutions are “actions to
protect, sustainably manage and restore
natural or modified ecosystems that
address societal challenges effectively
and adaptively, simultaneously providing
human well-being and biodiversity bene-
ts” (Cohen-Shacham et al., 2016). The
nature-based solutions approach is founded
on the concept that ecosystems innately
have various mechanisms that produce
services, which, in turn, provide social
and ecological co-benets for communi-
ties. For example, forests and trees provide
ecosystem services such as erosion control
and water regulation that help protect water
resources, manage stormwater, ensure
domestic water supplies, build resil-
ience to climate change and reduce the
risk of disasters. Development agencies,
including the World Bank, are promoting
nature-based solutions approaches to
protect, sustainably manage and restore
natural and managed systems and address
societal challenges, human well-being and
ecosystem services in an efcient and
adaptable manner (MacKinnon, Sobrevila
and Hickey, 2008). Nature-based solutions
involve the use of green and blue infra-
structure in its original form or designed
according to ecological principles to sup-
ply ecological services.
This article addresses the roles of urban
and peri-urban forests – including forested
watersheds in the hinterlands of cities – as
nature-based solutions for increasing water
© NIDHI NAGABH ATLA
Recreational shing in Windsor,
Ontario, C anada. Fishing is a common
urban activity requiring unpolluted
water and healthy ecosystems

45
Unasylva 250, Vol. 69, 2018/1
security. Because the focus of this article is
on forested landscapes, the terms “nature-
based solutions” and “green infrastructure”
are used synonymously.
CITIES NEED TO BE WATER-SMART
The need for nature-based solutions to
address water insecurity is increasingly
apparent. Traditionally, urban managers
have focused on increasing water supply
rather than managing demand. This has
led to a heavy reliance on large-scale grey-
infrastructure schemes such as large dams
and massive embankments along rivers and
coastal zones, which have proven expen-
sive – with high environmental, social and
political costs – but have failed to address
excessive water use. The outcome of this
myopic approach has been the further
deepening of water demands and the
exacerbation of water crises in urban and
peri-urban areas.
Water management in towns, cities
and municipalities needs to evolve from
conventional approaches towards innova-
tive management strategies that combine
natural (or “green”) and grey infrastructure
and include other multifaceted dimensions,
such as good governance, micronancing
for community-scale interventions, water-
related conflict management, pricing
policies, and strategies for disaster risk
reduction and community resilience.
Box 1 (see page 46) provides examples
of recent moves in this direction.
The UN Water for Life Decade (2005–
2015) brought together development actors,
agents and institutions to address water
security. Among other things, it gave rise to
the conceptual framework for water secu-
rity shown in Figure 1, which is designed to
guide efforts to address the cross-cutting,
multidimensional aspects of water-related
decision making (Mehta and Nagabhatla,
2017), including urban water manage-
ment. Increasingly, the global academic
community and development agencies
are prioritizing the water-security agenda
and recognizing the need for innovative,
cross-cutting approaches that integrate
grey and green infrastructure; there is an
urgent need to create “water-smart” and
“climate-resilient” cities (Nagabhatla and
Metcalfe, 2017).
Global demand for water is projected to
exceed supply in coming decades, but many
cities are already facing water crises as a
result of urbanization, aging infrastructure
and hydro-climatic variability. In October
2017, the World Water Council, with the
support of the Government of Morocco and
the United Nations Framework Convention
on Climate Change (UNFCCC), convened
an international meeting aimed at main-
taining water as an important element of
climate talks and to focus on water for
food and urban resilience. It has been
1
The water-s ecurity
conceptual framework
Sou rce: UN-Water (2013).
FINANCING
Innovative sources of financing
complement funding by the public
sector, including investments from
the private sector and
micro-financing schemes.
TRANSBOUNDARY
COOPERATION
Sovereign states discuss and
coordinate their actions to meet
the varied and sometimes
competing interests
for mutual benefit.
PEACE
AND
POLITICAL
STABILITY
The negative effects of conflicts are
avoided, including reduced water quality
and/or quantity, compromised water infrastructure,
human resources, related governance, and social or political systems.
Achieving water security requires collaboration across sectors, communities,
disciplines and political borders, to reduce the risk of potential conflicts
over water resources, between sectors and between water users or states.
What is
Water Security?
GOOD
GOVERNANCE
Adequate legal regimes,
institutions,
infrastructure
and capacity
are in place.
www.un.org/waterforlifedecade/water_cooperation www.unwater.org
“The capacity of a population to safeguard sustainable access to adequate
quantities of acceptable quality water for sustaining livelihoods, human
well-being, and socio-economic development, for ensuring protection against
water-borne pollution and water-related disasters, and for preserving
ecosystems in a climate of peace and political stability.”
Working definition, UN-Water, 2013
Water is central to achieving a larger sense of security, sustainability, development and human well-being.
UN-Water supports the inclusion of water security in the post-2015 development agenda as part of the
Sustainable Development Goals.
ECONOMIC
ACTIVITIES
AND
DEVELOPMENT
Adequate water supplies are available
for food and energy production,
industry, transport and tourism.
Adequate water supplies are available
for food and energy production,
industry, transport and tourism.
Populations have access to safe,
sufficient and affordable water to meet
basic needs for drinking, sanitation
and hygiene, to safeguard
health and well-being,
and to fulfill basic
human rights.
DRINKING
WATER AND
HUMAN WELL-BEING
Ecosystems are preserved and can
deliver their services, on which
both nature and people rely,
including the provision
of freshwater.
ECOSYSTEMS
WATER-RELATED
HAZARDS AND
CLIMATE CHANGE
Populations are resilient to water-related hazards
including floods, droughts
and pollution.
version October 2013

Unasylva 250, Vol. 69, 2018/1
46
estimated that protecting water sources,
including forests and trees on agricultural
land, could improve water quality for
more than 1.7 billion people living in cit-
ies globally – over half the world’s urban
population (Abell et al., 2017).
FORESTS AND WATER
It has been estimated that forested water-
sheds supply approximately 75 percent of
the world’s accessible freshwater resources
(Millennium Ecosystem Assessment,
2005). Forests increase soil inltration,
soil water-holding capacity and ground-
water recharge; regulate ows; reduce
soil erosion and sedimentation; and
contribute to cloud cover and precipita-
tion through evapotranspiration (Ellison
et al., 2017). Some forest ecosystems,
particularly tropical montane cloud forests
and dryland forests, increase net water
ow by condensing water from moist air
on their leaves, which then drips to the
ground. Forests also help reduce ooding
and the associated risks to property and
human safety.
Box 1
Nature-based solutions, urban development and
community resilience
Recent examples of nature-based solutions to water insecurity in an urban development
context include the following:
• The European Union’s Connecting Nature project is being implemented in 11 European
cities, one of seven European projects seeking nature-based solutions for smart cities and
climate change. The total investment of the suite of projects is EUR 150 million; the aim
is to help the transition to more sustainable and resilient cities (Thompson, 2017).
• China is investing heavily in innovative green infrastructure such as green roofs on build-
ings and urban wetlands, with the central goals of ood control, water conservation and
increasing the resilience of city inhabitants (Zweynert, 2017). Shenzhen, an emerging
smart city in Guangdong Province, is becoming an icon of international environmental
leadership by adoption a “green city” agenda. It is incorporating the concepts of green
energy, resilient communities and intelligent city infrastructure in its planning as part of
a nature-based solutions approach (Kam Ng, 2017).
• Architect s and urban planners in the Syrian Arab Republic are considering “people-centred”
housing strategies using local resources and approaches to infrastructure development in
an effort to create resilient cities (Zekavat, 2017).
• Taking note of intense weather, devastating hurricanes and frequent ooding episodes in
urban spaces, architects in the United States of America are proposing green solutions
that will embed and deploy ecological services and the benets of forested and aquatic
landscapes in the management of urban development (Lee, 2017).
© NIDHI NAGABH ATLA
The maintenance of
coastal vegetation
and forest fringes
in Shenzhen, China,
is a nature -based
solution to urban
problems and part
of creating a smart,
green city

47
Unasylva 250, Vol. 69, 2018/1
Healthy natural forests generally pro-
vide higher-quality, purer water than most
other land uses. An estimated 1.4 billion
people benet from forests due to reduc-
tions in sediments and nutrients in water
supplies (Abell et al., 2017). According
to Dudley and Stolton (2003), one-third
of the world’s 105 largest cities (selected
by geographical area) receive a signicant
proportion of their drinking water from
forested protected areas such as national
parks and wilderness areas. Investing in
the protection and sustainable management
of forested water catchments can reduce
costs associated with water treatment
(Ernst, 2004; WWAP, 2015). Maintaining
high water quality by investing in green
infrastructure may reduce the capital costs
of conventional treatments such as coagu-
lation, occulation and sedimentation and
more advanced treatment processes like
membrane ltration and activated carbon.
It is estimated that the protection of forests
as green infrastructure for water can cost
less than USD 2 per person per year, which
would be fully offset by savings from
reduced water treatment (World Bank,
2012; Abell et al., 2017).
FAO (2015) reported that approximately
25 percent of forests globally are managed
for soil and water protection, a proportion
that rose steadily from 1990 to 2015.
Although the global forest average has
increased, however, the area of tropical
and subtropical forests managed for soil and
water protection has declined, due mainly to
deforestation and conversion to other land
uses in Africa and Latin America. Tropical
and subtropical forests may be dispropor-
tionately important for water availability
because of their contributions to regional
precipitation through high rates of evapo-
transpiration and water recycling; mass
deforestation and conversion, on the other
hand, has been associated with reduced pre-
cipitation downwind (Ellison et al., 2017).
For example, recent droughts and water
scarcity affecting São Paulo, Brazil, and its
21.3 million inhabitants have been linked
to deforestation in the Amazon (Fearnside,
2005; Nobre, 2014; Watts, 2017).
Nature-based solutions in cities
The notion of conserving and managing for-
ests for water supply is not new, and many
nature-based solutions to water supply are
working effectively worldwide today. Some
are using payment schemes for ecosystem
services (“PES schemes”), whereby indi-
viduals or communities are incentivized
to protect and sustainably manage forests
through a fee paid by downstream water
companies and other users benefiting
from the improved management. In Quito,
Ecuador, and Costa Rica, for example, PES
schemes are in place to maintain green
infrastructure for the vital water-related eco-
system services it provides; similar schemes
are being implemented in other parts of
Latin America, such as Lima, Peru (Box 2).
Box 2
Addressing water security through greening infrastructure
in Lima
Lima, Peru, is the second-largest desert city in the world after Cairo, Egypt, and its 10 million
inhabitants put immense pressure on the surrounding environment and its natural resources,
including water and forests. Lima is in the Pacic Coast Basin, which has lost approximately
75 percent of its historical tree cover (Qin et al., 2016), and this vegetation loss has been
associated with changes in the region’s natural dry and wet seasons and an increased incidence
of droughts, oods and landslides (Barrett, 2017). The Pacic Coast Basin now supplies only
about 2 percent of the city’s water.*
The balance between water supply and demand is strained, with a high risk of water scarcity;
for example, water demand exceeded the renewable water supply in the dry season in 2015.
Wit h Lima pr ojected to grow by 1.4 percent per yea r, the scenario of demand exceeding sup-
ply is likely to become more frequent. Foreseeing this situation, the Peruvian Government
adopted the Law on the Mechanism for Ecosystem Service Compensation (2015) to guide
and oversee the process of introducing green infrastructure nationally. The law was based
on research by Gammie and de Bievre (2015), which showed that integrating existing grey
infrastructure with green infrastructure in the watersheds supplying Lima’s water could
reduce the dry-season decit by 90 percent, and this would be achieved at a lower cost than
by adding grey infrastructure alone. The new law is an opportunity for the water sector to
harmonize nature-based solutions with ongoing grey infrastructure projects.
Nature-based solutions such as reforestation, pastoral reforms and wetland restoration, as
well as other low-impact approaches such as t he rehabilitation of amunas,
#
have been planned
and are being implemented. Funding for the work will be provided by Lima’s water utility
authority, Servicio de Agua Potable y Alcantarillado de Lima (SEDAPAL), which has agreed
to earmark almost 5 percent of its water tariff (estimated at USD 110 million between 2015 and
2020) to address wat er management; 3.8 percent of the tarif f will be invested in cli mate- cha nge
adaptation and disaster risk reduction, and 1 percent will be spent on green infrastructure
projects to close the gap between Lima’s water demand and supply. SEDAPAL is develop-
ing a novel green infrastructure master plan to enhance and complement grey infrastructure
(SEDAPAL, 2016). Lima, therefore, is pioneering a new generation of integrated water and
landscape management, providing an example for other municipalities and countries to follow.
*
Most of the city’s water supply comes from the Rímac, Chillón and Lur ín watersheds in the Andes
and the Alto Mantaro watershed on the Amazonian side of the Andes.
# Amunas are stone canals built in the Andes by the Wari culture between 600 and 1000 CE, before
the rise of the Incas. Before modern times, amunas captured water from rivers in the mountains
during the rainy season and took it to places where it could inltrate rocks that fed year-round
springs fu rther down the mountains, so maint aining river ow during the dry season (Pearc e, 2015).

Unasylva 250, Vol. 69, 2018/1
48
A comparable PES scheme is working
successfully in Viet Nam, bringing money
and other incentives to forest conservation
and providing local communities with
powerful stakes in success. Cities in China
are using forest restoration to help manage
ooding, and local forest restoration has
also reduced ooding in Malaga, Spain.1
Discussions on “smart” and “climate-
resilient” cities are underway in some
countries, such as Australia, the United
Kingdom of Great Britain and Northern
Ireland, and the United States of America,
where national agencies provide spatially
distributed, easily accessible and often-
free data and information. The United
States Geological Survey, for example,
has a network of 1.5 million hydrometric
sites for gathering data on water.
2
Other
countries are in the process of develop-
ing information bases. Some countries
are using innovative economic and nan-
cial instruments to tackle urban water
management, such as pollution taxes for
managing costs related to decontamination
and for generating operational revenues
(OECD, 2012).
In other places, however, conditions
appear to have moved backwards. Jakarta,
Indonesia, receives a large fraction of its
water from two national parks, both of
which face serious problems of illegal
deforestation. In Africa, the rapidly grow-
ing port of Mombasa, Kenya, receives clear
and plentiful water from the Chillu Hills,
a protected area, but the forests there are
being illegally cut and degraded. The fate
of the forest that has supplied clean water
to Istanbul, Turkey, for thousands of years
remains uncertain because it has no formal
protection (Aydin et al., 2013).
Some tropical cities, especially coastal
cities with mangrove ecosystems, are
making conscious efforts to review their
urban and peri-urban forest management
strategies using a disaster risk reduction
“lens”. Mangrove ecosystems act as pro-
tective shields against the effects of wind
and wave erosion, storm surges and other
coastal hazards that affect people and
infrastructure (FAO, 2007). In addition,
coastal vegetation, especially mangrove
forests, can treat wastewater and remove
chemical contaminants (mainly total
suspended solids and heavy metals such
1
Large, frequent or exceptional precipitation
events can overwhelm both natural and engi-
neered defences – but forests can mitigate a
signicant proportion of minor to moderate
ooding events.
2
In contrast, Water Survey Canada’s Hydro-
metric Program operates just a few thousand
such sites, which are particularly sparse in the
north (Bakker, 2009).
© PREM NAGABHATLA
Lake Ontario and forest near the
industrialized “steel” city of Hamilton,
Ontario, C anada. The city is encouraging
nature-based solutions to help achieve
environmental sustainability

49
Unasylva 250, Vol. 69, 2018/1
as phosphorous, zinc, cadmium, lead and
nickel) (Tam and Wong, 1997; Boonsong,
Piyatiratitivorakul and Patanaponpaiboon,
2003), thereby mitigating coastal pollution
(Spalding et al., 2014). Other studies have
shown that mangrove forests can improve
water quality, especially in areas with
intensive aquaculture (Peng et al., 2009).
Urbanization is leading to the rapid
proliferation of medium-sized cities
(1 million inhabitants or more) in devel-
oping countries, where water supply is
often poorly or optimistically planned
and where there is a low level of under-
standing about the benets of maintaining
tree cover in catchments. It is projected
that, by 2025, 800 million people will be
living in countries or regions with abso-
lute water scarcity, and two-thirds of the
world’s people could be under water-stress
conditions (UNESCO, 2006). Decisions
to address water security have generally
already been made in the world’s major
cities, but there are opportunities to adopt
nature-based solutions in rapidly emerging
cities in Africa and Asia.
WATER SECURITY AND
SUSTAINABLE DEVELOPMENT
Water security is attracting increasing
policy attention. International deliberations
from the 1970s onwards (e.g. Habitat I in
1976, Habitat II in 1996 and Habitat III
in 2016), the Earth Summit, Rio+20,
climate-change discussions at the
UNFCCC, the Millennium Development
Goals (2000 –2010) and, most recently, the
Sustainable Development Goals (SDGs), as
set out in the 2030 Agenda for Sustainable
Development (United Nations, 2015), along
with global agreements such as the New
Urban Agenda and the Sendai Framework
(Figure 2), have all taken note of urban
issues, sometimes explicitly and at other
times as embedded objectives, goals
and targets.
The cross-cutting nature of the SDGs,
and the high level of commitment among
countries to implement them, gives impe-
tus to the recognition of the links between
forests and urban water security, including
in the monitoring and reporting of pro-
gress towards a more sustainable world.
Especially relevant SDGs are SDG 6 (clean
water and sanitation), SDG 11 (sustain-
able cities and communities), SDG 13
(climate action), and SDG 15 (life on land).
The links between forests and water are
explicitly mentioned in SDG targets 6.6
and 15.1 and implied in SDG target 11.a,
which calls for the support of “positive
economic, social and environmental links
between urban, peri-urban and rural areas
by strengthening national and regional
development planning”.
Although the links between forests and
water are recognized, however, they are not
adequately accounted for in the indicators
used for monitoring. Indicator 6.6.1, for
example, includes only swamp forests,
mangroves, and forests temporarily or per-
manently inundated by water (UN-Water,
2017). These forests undoubtedly have a
role in disaster risk reduction, but other
forests with potentially signicant value
for water-related ecosystem services are
unrecognized, such as forests managed
for water supply and other forest types
known to have strong roles in hydrologi-
cal cycles (e.g. riparian and cloud forests).
Indicator 15.1.2 focuses only on protection
for biodiversity and not other functions,
such as water-related ecosystem services.
None of the SDG targets considers the
spatial distribution or health of forests.
Thus, although the SDGs provide impor-
tant backing for nature-based solutions
as means for ensuring water security,
they could be greatly strengthened by the
inclusion of a wider set of goals relating
to forests and water supply. For example,
it would be useful to have an indicator for
2
Global agreements with
goals or ta rgets related
to urban wate r security
Sustainable Development
Goals (to 2030)
SDG 6: Clean water and
sanitation
SDG 11: Sustainable cities
and communities
SDG 13: Climate action
SDG 15: Life on land
Other targets that directly or
indirectly link to urban and
forested landscapes
New Urban Agenda
(to 2025)
Outlines the pathway towards
sustainable cities and human
settlements
Resilient cities – urban
governance and planning
Urban water management
Sendai Framework
(2015–2030)
Urban infrastructure and urban
planning is designed to reduce the
impact of natural disasters
Developing strategies that reduce
loss to economic, physical and
environmental assets of a countr y
and communities
Nature-based solutions
Protect, sustainably manage and
restore natural ecosystems in
urban areas
Address societal and climate
challenges in designing
interventions to ensure human
well-being and biodiversit y benets
Urban
water
security

Unasylva 250, Vol. 69, 2018/1
50
SDG 6.5 (on integrated water resource
management) addressing the health of for-
ested watersheds that are sources of urban
water. Existing data, such as FAO’s global
forest resources assessments (e.g. FAO,
2015) and the World Resources Institute’s
Global Forest Watch–Aqueduct Tool, could
be incorporated in the measurement of
existing indicators to recognize the inter-
connection of forests and water, improve
the analysis of progress towards the SDGs,
and better inform management decisions
at the national and local levels.
The goals and targets of the 2030 Agenda
for Sustainable Development, along with
other global agreements, require countries
to look for innovative, smart, collaborative
and sustainable solutions to urban issues.
For example, the recently convened Water
Desalination Symposium Africa 2017 fea-
tured discussions between government,
industry, academics and traders on ways of
tackling the water shortage in Cape Town,
South Africa, using a multistakeholder
approach. Similarly, a recent water crisis
in Bangalore, India, raised the alarm on
the need to make urban water security
a priority. In both cases, it is clear that
smart, strategic approaches are required to
manage water demand, including nature-
based solutions.
CONCLUSION
Water is a multisectoral issue. Ensuring
water security in urban, peri-urban and
rural contexts, therefore, requires a com-
mon framework and understanding and
a coherent policy approach among the
water, forest, land, urban, climate-change,
energy and other sectors. The acknowledg-
ment of urbanization as an issue in global
sustainable development frameworks is
encouraging for the future of urban
centres and their associated landscapes.
The recognition of integrated grey–green
approaches for addressing water security
and the conceptual framework proposed by
UN-Water (Figure 1) should be of interest,
therefore, to many stakeholders – such
as urban and regional planners, water
managers and policymakers, international
companies and organizations with large
water “footprints”, not-for-prot institu-
tions steering change, and communities.
Urban communities are just as vulnerable
as rural communities to natural hazards.
It is important, therefore, that they build
their capacity, evaluate their vulnerability,
and participate in designing and imple-
menting resiliency approaches, including
nature-based solutions, in the face of the
risks posed by environmental and climate
variability. Designing and planning for
water security requires collaboration
among stakeholders at the local to global
scales. Increasing green cover is also part
of the equation: smart, sustainable, forest
landscape protection strategies and invest-
ment plans will emphasize the security
and protection of urban and peri-urban
forests as green infrastructure for water.
In many cases, such strategies and plans
will require a better understanding of the
interconnections between urban ecosystem
services and sustainable urban develop-
ment planning and interventions.
Future innovations to improve urban
water security will likely involve the inte-
grated design of urban spaces to include,
for example, constructed wetlands, green
roofs and retention ponds. Overall, the
© PREM NAGABHATLA
The foreste d landscape
surrounding densely
urban Hong Kong,
China, is a s ource
of water and other
ecological benets
for city dwellers

51
Unasylva 250, Vol. 69, 2018/1
increasing acknowledgment, in global
sustainable development frameworks,
of the importance of urbanization is an
opportunity to address water security
in cities through innovative, long-term
nature-based solutions. u
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There is a pressing need to take
forests fully into account in
city risk reduction and disaster
management plans.
There is a need, therefore, for policies
and measures that reduce or eliminate
long-term risks to people and property
due to hazards and which strengthen the
resilience of cities and their structural ele-
ments in the face of increasingly extreme
stressors. The creation of UN-Habitat
in 2002 led to the development of strat-
egies for achieving and increasing urban
resilience to natural or human crises. The
United Nations Plan of Action on Disaster
Risk Reduction for Resilience, developed
in 2013, identies measures to strengthen
support for countries and communities
in managing disaster risk, including the
The role of urban and peri-urban forests in reducing
risks and managing disasters
P. Cariñanos, P. Calaza, J. Hiemstra, D. Pearlmutter and U. Vilhar
Paloma Cariña nos is Professor of Botany at the
University of Granad a, Spain, and a member of the
Silva Mediterranea Working Group on Urban and
Peri-urban Forestry (FAO WG7).
Pedro Calaza is Professor of Landscape
Archite cture at Escuela Gal lega del Paisaje, Spain,
Dean of Colegió Ocial de Ingenieros
Agr onom os , Spai n, an d a me mb er of FAO WG7.
Jelle Hiemstra is Senior Scientic Researcher,
Trees and Urban Green, at Wageningen University
and Research, t he Netherlands.
David Pearlmut ter is Professor of Arch itecture at
Ben-Gur ion University, the Negev, Israel.
Urša Vilhar is Research Fellow at the Depar tment
of Forest Ecology, Slovenian Forestry Inst itute,
and a me mb er o f FAO WG7.
© DAVID PEARLMU TTER
Above: Urban trees can dramatically
reduce th e radiant surface temperature
of paved areas and moderate the thermal
stress experienced by pedestrians
(note that blue and purple in the thermal
image indicate relatively cool areas)
The unplanned urbanization process
that many cities have undergone in
recent decades to accommodate
population growth has contributed to the
daily exposure of urban communities to
environmental risks that threaten their
health and well-being. In addition to the
poor living conditions in many cities,
residents face the risks posed by extreme
natural hazards such as storms, oods,
re and drought, which climate change is
exacerbating. Most regions of the world
are exposed to natural hazards that cause
signicant economic damage and the loss
of human lives. The risks posed by natural
hazards may be amplied in urban areas by
human interventions, potentially leading to
situations of accumulated risk and perma-
nent vulnerability (Figure 1). All sectors
of urban populations are exposed to these
risks, but the poor are especially vulnerable.

Unasylva 250, Vol. 69, 2018/1
54
implementation of the Sendai Framework
for Disaster Risk Reduction 2015–2030.
Among the priority lines of action in the
Sendai Framework are enhancing disas-
ter preparedness for effective responses
and “building back better” in recovery,
rehabilitation and reconstruction. This
means not only promoting resilience in
new and existing infrastructure but also
identifying areas that are safe for human
settlements and preserving ecosystem
functions (UNISDR, 2009).
One of the key measures for increasing
resilience in urban settings is the rein-
forcement of urban ecosystems to ensure
they have the capacity to reduce risks and
manage disasters. Urban green infrastruc
-
ture, of which urban and peri-urban forests
are the backbone, can boost resilience to
disasters and help minimize the intensity
of associated impacts. The establishment
of urban green infrastructure adheres to
the basic principles of proactive resilience
– efciency, diversity, interdependence,
strength, exibility, autonomy, planning
and adaptability (Table 1) (Bell, 2002).
This article presents examples of the role
of urban and peri-urban forests in reducing
the impact of hazards, both natural and those
caused by human interventions. It also looks
at how hazards presented by urban and
peri-urban forests can be managed, thereby
increasing urban resilience in light of the
challenges to be faced in coming decades.
URBAN HAZARDS ASSOCIATED
WITH CLIMATE CHANGE
Climate change is often considered synony-
mous with global warming, but we are
living in an era of climatic uncertainty –
with localized events that have usually been
considered extreme becoming increasingly
frequent (Meir and Pearlmutter, 2010).
Communities around the world are experi-
encing upsurges in catastrophic storms,
ooding, heatwaves and droughts, and
these disruptive events will likely become
more pronounced in the future.
1
Disaste r risk as the product
of hazard a nd vulnerability
Disaster risk for …
Vulnerability
(physical, economic, social and environmental factors)
Natural hazards
Natural causes
Technological hazards
Human causes
Sou rce: International Federation of Surveyors (2006).
Humans Fauna
Flora
Soil
Water
Climate
Cultural
goods
=
× ×
Feedback
TABLE 1. Urban hazards and the role of urban and peri-urban forests in
risk reduction
Hazard Role of urban and peri-urban forests
Natural
Strong winds (e.g.
cyclones, hurricanes)
Act as barriers; reduce wind speed; work as protection screens
Flooding and drought Reduce stormwater volumes and ood risk; increase precipitation
interception; increase water inltration and groundwater recharge
Landslides Increase stability of steep slopes by reducing surface run-off and
erosion
Soil loss Prevent soil erosion; reduce impact of raindrops on soil surfaces;
improve soil-water retention
Extreme heat and
cold events, urban
“heat island” effect
Cool by shading, evapotranspiration, etc.; protect from hot and cold
winds
Wildres Reduce re intensity, ammability and spread when properly
designed and managed
Biodiversity loss Conserve species and habitats; limit spread of invasive species
Pests and diseases Limit spread and impacts
Anthropogenic
Air pollution Sequester carbon; reduce ozone formation; capture particulate and
gaseous pollutants; reduce emission of allergens
Pests and diseases Provide buffer against invasive species
Reduced physical
and mental health
Provide pleasant spaces that increase well-being, social cohesion
and interaction, and leisure activities, etc.

55
Unasylva 250, Vol. 69, 2018/1
Urban heat island effect
The urban “heat island” effect is a com-
monly observed example of local climate
change, which is intensied by a city’s
size, density and material composition.
One of the main catalysts of urban heat
islands is the replacement of vegetated ter-
rain with “dry” urban landscapes, thereby
reducing the cooling achieved through
evapotranspiration (Pearlmutter, Krüger
and Berliner, 2009) and – most importantly
for human thermal stress – by the shading
of pedestrians. Heat stress is intensied by
unshaded urban surfaces, which absorb
solar energy and re-radiate heat and reect
solar energy directly onto the bodies of
pedestrians.
The most effective general strategy for
mitigating the urban heat island effect
is the cultivation of trees in and around
cities. The magnitude of the “park cool
island” effect – that is, the reduction of air
temperature in urban green spaces relative
to their built-up surroundings – is typically
in the range of 3–5 °C but can reach nearly
10 °C (Hiemstra et al., 2017). Tree canopies
are especially benecial for shading when
they are broad and dense and their leaves
are transpiring freely (Shashua-Bar and
Hoffman, 2004); a lack of water in urban
areas is often a constraint, however.
In the United Kingdom of Great Britain
and Northern Ireland, London is likely to
face increasingly frequent heat events in
com ing years, with potentially signicant
effects on public health and the associated
risk of hundreds of deaths in heatwaves.
The city established a climate-change
adaptation strategy in 2010 that identies
the risks to public health posed by climate
change and sets out the actions needed to
manage them. An action now underway
is to leverage the benets of urban forests
by increasing the number of green roofs
and street trees and the quantity and
quality of green spaces. The objective is
to increase tree cover in Greater London
by 10 percent and achieve a total green
cover of 50 percent by 2050 (Mayor of
London, 2017).
Floods and storms
Overwhelming stormwater volumes and
ooding in urbanizing cities associated
with deteriorating drinking-water quality
have become major health, environmental
and nancial concerns globally. Increased
urbanization alters the hydrology of an
area, reducing the inltration capacity of
soils and increasing both surface-water
run-off and peak discharges (Vilhar, 2017).
The increased incidence of ooding in
cities demonstrates that the existing grey
infrastructure for conveying stormwater
to wastewater treatment facilities or into
surface waters was not designed for cur-
rent rainfall intensities. In most urbanized
watersheds, too, the area of impervious
surfaces is increasing. Urban and peri-
urban forests have great potential to reduce
stormwater run-off by increasing evapo-
transpiration and water inltration into
the soil (Gregory et al., 2006) and by the
interception of precipitation by tree crowns
(Kermavnar and Vilhar, 2017). Tree roots
and leaf litter stabilize soil and reduce
erosion (Seitz and Escobedo, 2008).
Floods are the most frequent disasters
in many areas of Asia and the Pacic.
Ten of the countries most exposed to
ood risks in the region (Afghanistan,
© IZTOK SINJ UR
Flooding after heavy rain in
Ljubljana , Slovenia. Tree roots are
helping protect the soil from erosion

Unasylva 250, Vol. 69, 2018/1
56
Bangladesh, Cambodia, China, India,
Indonesia, Myanmar, Pakistan, Thailand
and Viet Nam) are riparian, and trans-
boundary oods occur frequently, causing
large-scale impacts (Luo et al., 2015). In
Bangladesh, practices under implemen-
tation to reduce the impacts of ooding
include the development of advanced
simulated weather forecasting to enable
the evacuation of large numbers of people
several days in advance of ooding events,
the planting of ood-resistant trees, and
stronger regional cooperation to coordi-
nate response measures (Basak, Basak
and Rahman, 2015).
Hurricanes and windstorms
Hurricanes and other windstorms are pre-
dicted to occur at an increased frequency
and severity due to global warming (e.g.
in the Atlantic: Bender et al., 2010). Like
other kinds of infrastructure, trees can
be damaged by high winds and storms,
but they can also contribute to hurricane-
resistant landscapes. Duryea, Kampf and
Littell (2007) studied ten recent hurricanes
and their impacts on more than 150 urban
tree species to assess the factors that make
trees wind-resistant. Trees best able to sur-
vive storms are compact and have a major
taproot and well-developed secondary
roots, a well-tapered trunk, a low centre
of gravity, and open, exible and short
branches. Trees in groups of ve or more
are also more likely than individual trees to
survive high winds. Only 3 percent of more
than 14 000 historic trees in New Orleans,
United States of America, were lost during
Hurricane Katrina in 2005; most of the
survivors were oaks, with many of the
characteristics listed above. The lessons
learned from the study by Duryea, Kampf
and Littell (2007) and others are being put
to use in areas devastated by the successive
hurricanes that hit the Caribbean and the
Gulf of Mexico in 2017.
Risk mitigation and disaster management
plans developed by the local government
of Kathmandu, Nepal, after the earthquake
in 2015 include the development of urban
forests and open spaces as measures to
reduce earthquake impacts and provide
community gathering points and tempo-
rary shelter (Saxena, 2016).
Forest res in the Mediterranean
Forest res, especially at the wildland–
urban interface, pose an increasing threat
to cities in the face of climate change.
People cause more than 90 percent of forest
res in the Mediterranean region, where,
on average, more than 800 000 hectares
burn each year. Droughts have lengthened
in recent decades, leading to an increase
in the number, extent and recurrence of
res and the scale of human and economic
losses (Gonçalves and Sousa, 2017).
Martínez, Vega-García and Chuvieco
(2009) found that the main factors asso-
ciated with high forest re risk in Spain
were landscape fragmentation, agricultural
abandonment and development processes.
On the other hand, policies to encourage
the afforestation of abandoned agricultural
land had little effect on re occurrence.
Portugal has experienced high recent
losses due to re: there were more than
500 fires in the summer of 2017, for
example, and more than 100 fatalities.
Since 2005, the country has been imple-
menting the Portuguese National Plan for
Prevention and Protection Against Fires
(Oliveira, 2005), which is intended as the
main approach for addressing one of the
country’s chief threats. Among the meas-
ures indicated in the plan is the progressive
replacement of eucalypt forests: the
country has more than 900 000 hectares
of plantations of these trees, the leaves and
bark of which are highly ammable. The
abandonment of agricultural lands and the
expansion of urban centres have brought
eucalypt forests closer to the peri-urban
fringe, increasing the risk of re at the
urban–rural interface.
Threats to biodiversity
Tree pests and diseases have spread
globally and are causing considerable
damage. For example, Dutch elm disease
(Ophiostoma ulmi and O. novo-ulmi) was
transported from Asia to the Americas
© PEDRO CALAZ A
Urban tre es can pose hazards: this tree
has fallen on a children’s playground,
although fortunately no one was hurt

57
Unasylva 250, Vol. 69, 2018/1
and Europe during the twentieth century
by means of infected logs, resulting in a
pandemic in the Northern Hemisphere.
In the United Kingdom of Great Britain
and Northern Ireland alone, Dutch elm
disease caused the deaths of about 28 mil-
lion mature elms in 1970–1990, many of
them in urban and peri-urban areas, and
the subsequent death of about 20 million
young elms (Brasier, 2008).
Many cities are adopting policies to
ensure sufcient tree species diversity
in cities to reduce the impacts of pests,
diseases and other factors that might other-
wise cause the decimation of urban trees. In
Canada, one of the objectives of the City of
Kelowna Sustainable Urban Forest Strategy
is to increase species diversity across the
city to avoid the catastrophic loss of trees
through pests, diseases and climate change.
The strategy calls for the diversication of
the species used as street trees so that ten or
more species are represented at 10 percent
or less of the total street-tree population.
Ornamental species compatible with the
city’s climatic conditions are being intro-
duced (Blackwell and Associates, 2011).
Urban areas can contain relatively high
levels of biodiversity (Alvey, 2006). Cities
are adopting management practices to con-
serve and promote such diversity, including
as a means to increase resilience in the
face of environmental change.
HUMAN HEALTH RISKS
AND BENEFITS
Modern urban living can have negative
impacts on public health and the qual-
ity of life of citizens. According to the
World Health Organization, an estimated
12.6 million deaths each year are attrib-
utable to unhealthy urban environments
(Prüss-Ustün et al., 2016), with air, water
and soil pollution, chemical exposure
and climate change linked to more than
100 types of ailment; cardiovascular and
respiratory diseases are among the top
ten causes of environment-related deaths.
Urban and peri-urban forests pose risks
to human health but can also have a wide
range of health benets.
Risks
Vegetal substances can be toxic to humans,
and trees and other plants can emit vola-
tile organic compounds and particulate
material that can adversely affect human
health (Cariñanos et al., 2017). Some of the
most frequently used species in urban and
peri-urban forests worldwide have been
identied as the main causative agents of
human pollen allergies (Cariñanos and
Casares-Porcel, 2011).
People are also at risk of being hurt
or killed by falling trees. For example,
a 200-year-old oak fell on a crowd of
people on the island of Madeira, Portugal,
in August 2017, killing 13 and injuring
nearly 50 (Minder and Stevens, 2017).
The risks posed by urban and peri-urban
forests can be managed by implement-
ing an urban tree hazards plan (Calaza
Martínez and Iglesias Díaz, 2016). For
example, the Master Plan for the Trees of
the Jardines del Buen Retiro in Madrid,
Spain, includes a tree risk management
plan that, among other things, establishes
a risk management protocol for the park.
Benets
Numerous studies have highlighted the
role of green infrastructure in general,
and urban and peri-urban forests in par-
ticular, in promoting human health. Many
initiatives have been launched – some
supported by national health services and
the World Health Organization – aimed
at encouraging the use of urban and
peri-urban forests for physical activities
and other forms of outdoor recreation to
improve human health (World Health
Organization, 2010).
Green spaces, including urban and
peri-urban forests, can provide a form of
natural therapy that helps people recover
from traumatic events, such as disasters.
Activities with potentially therapeutic
benets include planting gardens for peace
and reconciliation and caring for surviv-
ing trees or planting new trees in areas
affected by war, terrorist attacks or natural
disasters (Tidball et al., 2010).
CONCLUSION
In an era in which extreme natural events
are becoming more frequent, there is a
pressing need to develop and implement
risk reduction and disaster management
plans in cities to reduce vulnerability and
exposure to risks and improve adaptive
capacity. Urban and peri-urban forests
are key components of such plans, both to
minimize the impacts of disasters and the
damage they cause and to restore, rebuild
and rehabilitate urban ecosystems in the
aftermath. The multifunctionality of urban
and peri-urban forests, their effectiveness
in mitigating ooding, extreme heat events
and strong winds, and the hazards they
themselves pose, make it imperative that
they are taken into consideration in action
plans for disaster risk reduction.
The increasing risk to human health and
welfare posed by human activities such
as air, water and soil pollution also indi-
cates the need to install and manage urban
green infrastructure, especially urban and
peri-urban forests, as a measure to protect
people, built infrastructure and habitats.
Finally, given the transnational charac-
ter of some of the impacts of disasters,
transboundary and regional cooperation
is crucial for developing policies and
strategies for risk preparedness and dis-
aster impact mitigation and coordinating
response measures. u

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Urban and peri-urban forests
can produce a range of foods to
supplement local diets and provide
a focus for community activity. F
eeding an increasingly urban popu-
lation and ensuring the economic
and social well-being of urban
dwellers will be the primary challenge for
cities in coming decades. The impacts of
climate change are expected to slow down
urban economic growth, exacerbate envi-
ronmental degradation, increase poverty
and erode urban food security. Many cities
are on a quest for more sustainable urbani-
zation pathways that will enable effective
responses to the increasing socio-economic
and environmental challenges they face.
In the search to “make cities and human
settlements inclusive, safe, resilient and
sustainable” (Sustainable Development
Goal 11 in the United Nations Sustainable
Development Agenda 2030), interest is
increasing in growing local food. Edible
green infrastructure, mainly in the form
of urban food forests and trees (referred
to here generally as urban food forests
and also sometimes as tree-based edible
landscaping), can help address a range of
problems caused by rapid and unplanned
urbanization, such as food scarcity, pov-
erty, the deterioration of human health and
well-being, air pollution, and biodiversity
loss (FAO, 2016).
The use of edible plants in urban and
peri-urban forestry varies among cities
and is inuenced by historical, cultural
and socio-economic factors. Overall, it has
tended to be neglected in modern cities.
“Edible” urban forests as part of inclusive,
sustainable cities
J. Castro, S. Krajter Ostoić, P. Cariñanos, A. Fini and T. Sitzia
José Castro is P rofessor of Landscape
Ecology at the Polyte chnic of Bragança,
Portugal, a nd a member of the Silva
Mediterranea Working Group on Urban and
Peri-urban Forestry (FAO WG7).
Sil vija Kr ajt er O st oi ć is Res earch Associate
and Head of Department at the Croatian Forest
Research Institute, and a member of FAO WG7.
Paloma Cariña nos is Professor of Botany at the
University of Granad a, Spain, and a member of
FAO WG7.
Alessio F ini is Associate P rofessor of
Arbor iculture and Urban Forest ry at the
Depar tment of Agricultur al and Environment al
Sciences – Pro duction, Landscape and
Agroenergy, University of Milan, Ita ly, and a
member of FAO WG7.
Tommaso Sitzia is Assistant Professor at the
University of Padova, Italy, and a member of
FAO WG7.
© PALOMA CARI ÑANOS
Above: The pomegranate (Punica
granatum) – “granada” in Spanish –
is the heraldic symbol of the city of
Granada, Spain, where it appears
on streets throughout the town. It
produces a highly nutritious fruit

Unasylva 250, Vol. 69, 2018/1
60
This article explores the potential of urban
and peri-urban forests as sources of food
and the role that urban food forests can
play in fostering sustainable cities.
WHAT ARE URBAN FOOD FORESTS?
Clark and Nicholas (2013) dened urban
food forests and trees as “the intentional
and strategic use of woody perennial
food-producing species in edible urban
landscapes to improve the sustainability
and resilience of urban communities”. As
an “edible landscaping” practice, urban
food forestry involves a combination of
agriculture, forestry and agroforestry in
urban areas to supply cities with food. It
may involve various species of fruit and
nut trees, berry bushes, vegetables, herbs,
edible owers and other ornamental plants.
The integration of urban food forests
into the infrastructure of a city can pro-
vide urban dwellers with many benets.
There is evidence that urban food forests
can motivate stewardship practices and
give inhabitants opportunities to interact
with nature and each other (McLain et al.,
2012); enable the development of more
resilient food systems and promote social
and environmental sustainability (Yates,
2014); improve social cohesion and well-
being and strengthen local communities
(Lwasa et al., 2015); enhance biodiversity
(Dennis and James, 2016); and provide
economic benets for both municipalities
and citizens (Lafontaine-Messier, Gélinas
and Olivier, 2016).
Tree-based edible landscaping in urban
areas has been practised since ancient
times. Ancient Egyptian and Persian gar-
dens combined fruit trees with owers,
ponds, pot plants, vine-clad pergolas and
places to sit in winter sun or summer shade.
Classical ornamental gardens had water
channels, pools, fountains and cascades
cooling the air, owers producing scents,
and fruit trees providing food and shade.
Medieval monastic gardens produced fresh
fruit and vegetables, as well as owers
and medicinal herbs. Renaissance estates
had plots and terracotta pots for growing
owers and producing fruit, vegetables and
herbs that were sold locally to raise funds
for maintenance.
In the Industrial Revolution in the nine-
teenth century, however, the edible elements
of urban landscapes tended to be replaced
by ornamental vegetation. Today, most
cityscapes are largely devoid of edible com-
ponents and instead feature traditional shade
trees, lawns and other soil-cover plantings.
Urban food forest typologies are inu-
enced by city histories. In Central America,
for example, native gardens of multistrata
agroforestry systems coexist with colonial
cityscapes featuring large trees and exotic
plants (González-García and Gómez-Sal,
2008). Socio-economic circumstances may
also play a role: in Berlin, Germany, the esti-
mated fruit-tree density is still signicantly
higher in the eastern part of the city than in
the west (8.6 trees/ha versus 1.6 trees/ha)
(Larondelle and Strohbach, 2016).
EFFORTS TO APPLY URBAN FOOD
FORESTRY WORLDWIDE
The applicability of urban food forestry
and its efcacy in addressing social and
environmental challenges depend on a
range of social, environmental and other
local factors. Only a few examples exist
of modern efforts to encourage urban food
forestry, and these are mostly limited to
relatively small urban settings.
In Todmorden, West Yorkshire, in the
United Kingdom of Great Britain and
Northern Ireland, volunteers grow fruit,
herbs and vegetables for everyone to share;
they do so without paid staff, buildings
or funding from statutory organizations.
The volunteers also run events to help
strengthen the local community; income
is generated through donations and fees
for talks and tours (Incredible Edible
Todmorden, undated). In Copenhagen,
Denmark, in contrast, citizens do not
collect fruit from urban forests because it
is widely perceived that doing so would
break social norms (Yates, 2014).
United States of America
Among examples of urban food forestry
in the United States of America, Seattle’s
urban food forest (McLain et al., 2012) is
probably the best-studied. Seattle Public
Utilities owns the Beacon Food Forest,
but the forest’s fruit trees were planted
by community volunteers, many of whom
continue to work in the forest and maintain
the orchards. Ongoing participation gives
community members a sense of steward-
ship and pride in the space.
Lemon Grove – a municipality of
26 000 inhabitants in California – is
preparing to grow public orchards in city
parks as part of efforts to preserve the city’s
history and small-town charm. Issues to be
addressed in selecting sites for fruit trees
include proximity to roadways and side-
walks; accessibility for mobility-impaired
individuals; access for maintenance; and
input from community members and
garden experts (Federman, 2017).
The San Francisco Urban Orchard
Project provides ongoing resources for
the planting and maintenance of publicly
accessible fruit trees. The programme part-
ners with local not-for-prot organizations
to plant fruit- and nut-tree orchards and to
assist community-based groups in their
roles as local stewards of green spaces
(SF Environment, undated).
Barnum is one of eight city parks in
Denver, Colorado, with urban orchards.
It is in what used to be one of the city’s
least desirable neighbourhoods, but things
took a turn for the better when Denver
Urban Gardens – a not-for-prot organi-
zation that supports community gardens
in the city – purchased a vacant lot. This
is now a community orchard that grows
red currants, raspberries, grapes and
winter squash among fruit trees (Extreme
Community Makeover, 2016).
Developing countries
Rapid urbanization in many developing
countries is leading to increased urban
poverty and pressure on green spaces.
Edible landscaping is often in the form
of small-scale subsistence agriculture, and
such gardens represent signicant propor-
tions of urban green infrastructure. Even
in inner-city areas, residents cultivate

61
Unasylva 250, Vol. 69, 2018/1
roadsides and riverbanks, along railroads,
on vacant private lands and in parks, based
on minimal user rights such as informal
rents, leases and inheritances. In Taipei,
Taiwan Province of China, however, the
law forbids the planting of fruit trees and
vegetables in parks and public spaces
(Chang et al., 2016).
Disputes arise about who can plant, har-
vest or otherwise use urban forests when
laws or ordinances do not specify rights
for the use of common areas (Rana, 2008).
Fear of eviction is a strong disincentive for
people to introduce food trees and shrubs.
In illegal settlements in Kathmandu and
Lalitpur, Nepal, people grow seasonal food
crops but do not care for “doubt tenure”
trees. In South Africa, homestead fruit and
nut trees are important sources of food,
especially in informal settlements, where
the poorest people live. Residents of new
low-cost housing make especially exten-
sive use of urban tree products harvested
in public urban spaces because they have
fewer homestead trees than residents in
informal areas and townships (Kaoma and
Shackleton, 2014).
Urban food forestry is not widely
implemented in Asia and the Pacic, but
innovative urban forestry practices are
evolving in the region (Kuchelmeister,
1998). In China, residents can harvest fruit
in many parks; in Queensland, Australia,
residents and schools maintain edible pub-
lic parks, producing fruit, herbs, owers
and vegetables (Kuchelmeister, 1998).
Africa
Agroforestry gardens are probably the
most signicant type of urban green space
in West African countries (Fuwape and
Onyekwelu, 2011). In arid and semiarid
areas, it is common practice to establish
windbreaks to protect urban areas and
enhance soil productivity (Kuchelmeister,
1998). Urban forest practices that contribute
to food security include collecting wild
edible plants, planting fruit-bearing street
trees, and establishing medicinal public
parks. Fruit trees are planted in many
residential compounds, especially those on
urban fringes and in new urban settlements.
Despite the marked differences in the
sociospatial and environmental settings
of Botswana, Cameroon, Côte d’Ivoire,
South Africa and the United Republic of
Tanzania, wild food trees are integral to
most urban and peri-urban households
in small and mid-sized cities in those
countries. This applies not only to poor
families lacking access to productive soils
© JOSÉ CASTRO
An educational initiative in Chinandega,
Nicaragua, is designe d to help protect
urban fruit trees, such as this large
mango tre e (Mangifera indica). Fruit
trees are common in indigenous
neighbourhoods in Central America

Unasylva 250, Vol. 69, 2018/1
62
but also to those with a higher standard
of living (Schlesinger, Drescher and
Shackleton, 2015). A study in Senegal
nearly three decades ago (Brun, Reynaud
and Chevassus-Agnes, 1989) found that
urban food forests did not make a signi-
cant contribution to food consumption and
nutrition but were instrumental in improv-
ing the income and social status of women
and increasing their awareness of evolving
food habits in urban areas.
In Cabo Verde, the extent of urban food
forestry varies according to the actors
involved. Trees planted and managed by
municipalities are mostly ornamental, while
those planted and cared for by residents
are usually fruit trees (e.g. Carica papaya,
Mangifera indica and Terminalia catappa).
ISSUES FACING URBAN FOOD
FORESTS AND TREES
Research and literature on urban food
forestry are scarce, despite the long history
of growing forest foods in urban areas.
Most existing studies report specic cases
of local food production from urban food
forests, and there have been few attempts
to explore the adaptation and application
of local practices in other contexts or to
scale them up. The lack of research prob-
ably reects the general bias of studies
on urban ecosystem services in western
Europe and North America, where cities
today depend mostly on outside sources
of food (Larondelle and Strohbach, 2016).
Although edible urban landscapes were
widely used for centuries in the European
Mediterranean, the contributions of such
landscapes to the livelihoods of modern
urban communities are far from fully
explored. Of existing experiments, none has
explicitly addressed the food-provisioning
aspects of urban trees (Valette, Perrin
and Soulard, 2012). A recent review of
urban food forestry collected information
on 37 initiatives worldwide (Clark and
Nicholas, 2013): it evaluated 30 urban forest
master plans in various cities and found
that human food security was a primary
objective in only four of them.
Russo et al. (2017) analysed more than
80 peer-reviewed publications focusing on
urban ecosystem services and disservices.
They identied eight typologies of edible
green infrastructure, including edible
forest gardens and edible urban forests,
which were addressed in 38 percent of the
publications. Some publications showed
urban food forestry to be a multifunctional
urban landscape practice combining an
extended range of ecosystem services
efciently in cities and integrating the
provision of food with environmental,
sanitary, social, cultural and economic
co-benets. Evidence of the trade-offs
between the supporting, provisioning,
regulating and cultural services of urban
food forests is lacking, however.
Also lacking is a conceptual framework
that would enable the synthesis and analy-
sis of existing knowledge on urban food
forestry. Such a framework is needed to
integrate the relevant aspects of urban
food forestry into urban planning, such
as the area required, species, knowledge,
© JOSÉ CASTRO
In public a reas
of impoverished
districts in
Cabo Verde, people
plant, care for and
protect fruit trees
in preference to
ornamental trees

63
Unasylva 250, Vol. 69, 2018/1
management, governance, and nancial
and human resources. As to the area
needed, Richardson and Moskal (2016)
calculated that a 58-km buffer around
Seattle would be required to meet 100 per-
cent of the city’s food needs.
In most countries, the actual and poten-
tial contribution of urban food forestry
to sustainable and resilient urban devel-
opment models is unknown. Although
research into, and the practice of, urban
agriculture is growing, urban food forestry
has been implemented systematically in
only a few countries, and its practices are
little explored.
Risks of urban food forestry
Certain risks are associated with the
implementation of urban food forestry.
Poe et al. (2013), for example, pointed
out that the toxicological profiles of
urban soils should be investigated before
they are used for urban food forestry to
avoid health risks posed by the uptake by
plants of pollutants such as heavy metals.
Species selection and cultural techniques
can also help prevent the accumulation of
pollutants in the edible parts of plants:
the translocation of pollutants absorbed
by roots to edible parts, as well as the
amount of airborne pollutants penetrat-
ing the fruit epicarp, has been shown to
differ widely by species (von Hoffen and
Säumel, 2014).
Vegetables from urban and peri-urban
farming may contain unacceptable quanti-
ties of trace elements (Nabulo et al., 2012;
Samsøe-Petersen et al., 2002; Säumel et al.,
2012); on the other hand, some studies
have found it possible to produce healthy
food from fruit trees grown along streets
in large cities (von Hoffen and Säumel,
2014). The apparent discrepancy between
studies on the health risks of urban food
forestry may be due to soil characteristics
and the plant species used.
Another health risk that can occur from
the consumption of raw fruit produced in
urban food forests is an allergic reaction
known as oral allergy syndrome. This
can occur in sensitized individuals due to
cross-reactions between aeroallergens and
food allergens – such as between pollen
produced by species in the Cupressaceae
family and the fruit of Prunus persica,
giving rise to “cypress–peach syndrome”
(Popescu, 2015).
Unharvested fruit can be hazardous and
unsightly when they drop from trees, and
they can also attract vermin and pests.
Highly perishable crops require quick
processing, such as canning, freezing or
drying, or sufcient people to quickly
consume surplus supplies (Brown, 2016).
Most widely used fruit tree species
belong to only a few families or genera
© JOSÉ CASTRO
Orange trees planted
as part of a new
urban development
in Porto, Portugal.
Urban food
forestry involves a
combination of urban
agriculture, forestry
and agroforestry
techniques and
strategies

Unasylva 250, Vol. 69, 2018/1
64
(e.g. Rosaceae in temperate environments).
But the use of a small number of species
may challenge the 30–20–10 biodiversity
rule proposed by Santamour (1990) to
maximize protection against pest out-
breaks.
1
Many commonly grown fruit
trees are indeed very sensitive to pests
and pathogens, but this can be managed
through wise, inventory-based species
selection. New releases and the restora-
tion of ancient resistant cultivars of widely
used species, as well as the use of minor,
neglected species with edible uses, might
help improve the tolerance of urban food
forests to pests and diseases.
Urban food forestry strategies
The development of an urban food forestry
strategy requires a broad range of exper-
tise to ensure a comprehensive approach.
It involves the integration of knowledge
from social and environmental sciences
and disciplines such as urban forestry and
arboriculture, urban agriculture, urban
ecology, landscape and urban architec-
ture, economics, policy and governance.
Effective, efcient collaboration among
experts, policymakers, local governments,
the private sector and citizens is essential
to ensure effective urban food forestry.
CONCLUSION
The examples in this article show that
urban food forestry can be applied in
diverse contexts and to meet various
objectives. Urban food forests and trees
are located mostly on formal and informal
public land, and implementing an urban
food forest approach depends on owner-
ship, local rules, norms, policies, and an
effective governance model. Comparative
studies and lessons learned are needed to
understand the most effective approaches
in different contexts.
The consideration of urban food for-
ests and trees and their integration into
regional, national and local urban policies
can provide a pathway towards sustainable
urban development. Developed countries
have started to rediscover urban tree-based
edible landscaping but, in most cases, food
production is still not the primary objec-
tive of urban and peri-urban forestry. In
developing countries, knowledge gaps need
to be identied to stimulate research on
strategies to consolidate traditional models
of tree-based edible landscaping and to
foster new approaches.
The potential of urban food forests is
still far from adequately exploited, and
there is a need to develop modelling tools,
advanced design principles, and efcient
management and governance strategies.
Initiatives are needed to gather knowl-
edge on existing efforts and to fully assess
issues associated with food safety, such
as the risks posed by soil, water and air
pollution.
Further research is needed to identify
the species, compositions and congura-
tions that will maximize the benets of
urban food forests for local communities
and minimize the risks to human health.
Cultivars and genotypes are needed that
are adapted to harsh urban environments,
especially in the context of climate change.
Collaboration – subnationally, nationally
and internationally – among scientists,
citizens, policymakers and city managers
is crucial for establishing a robust con-
ceptual framework for urban food forests.
It is also desirable to compile traditional
tree-based edible landscaping practices to
guide the design of projects in which food
production is the central objective. Urban
food forests are potentially a valuable
multifunctional component of the broader
green infrastructure of the cities of the
future and can help achieve the Sustainable
Development Goals. u
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66
Some individual trees perform
especially important cultural
functions, and strong community
involvement is crucial for their
conservation and management
in urban settings.
P
eople have held trees in high esteem
and awe since antiquity. Primitive
peoples recognized that trees were
notably bigger, stronger, more majestic
and longer-lived than most other organ-
isms. Intimate interactions with nature
have increased human awareness of trees
progressively; over time, particular trees
have instilled in people a sense of frater-
nity, fear, generosity, providence, ubiquity,
immortality, eternity and divinity.
As benevolent providers and protectors
of humans, certain trees have acquired
special status. Beginning with admiration
and respect, attitudes evolved to adora-
tion and reverence and then to veneration
and worship (Taylor, 1979; Dafni, 2006).
Traversing geographical, temporal and
cultural divides, tree worship is com-
mon in many ancient polytheistic belief
systems. Many mythologies, legends and
folklores are associated with beloved or
feared trees, indicating a continued and
widespread human deference to them.
Many indigenous cultures have bestowed
a sacred standing on individual trees and
groves, seeing them as deities or the abodes
of certain spirits.
The pragmatic contributions of trees to
farming communities in soil and water
conservation and microclimatic ameliora-
tion are well recognized. In East Asia,
such contributions have been practised
systematically as feng shui or geomancy
(Han, 2001; Coggins et al., 2012). Such
Protecting heritage trees in urban
and peri-urban environments
C.Y. Jim
C.Y. Jim is Chair P rofessor, Department of
Geography, University of Hong Kong, Hong
Kong, China.
© C.Y. JIM
Above: Traditional villages in southern
China are protected by upslope feng
shui (geomancy) groves. This photo
shows the well-preserved tradition in
the village of Lai Chi Wo, Hong Kong

67
Unasylva 250, Vol. 69, 2018/1
indigenous knowledge reflects the
traditional wisdom of learning from and
mimicking nature to create a harmoni-
ous and healthy milieu for humans and
to tackle the capriciousness and harshness
of nature. Translated into adaptive prac-
tices, feng shui has provided a collective
community-based and holistic resource-
management system (Gadgil, Berkes and
Folke, 1993) that has fostered the persis-
tence of agrarian cultures for millennia.
In modern societies, systematic forest
management by governments or other
agents sometimes recognizes and protects
sacred trees. Associated with human settle-
ments, such trees may be subsumed in
urban and peri-urban forestry, but local
customs may also continue to defend them
in unwritten codes. Superstitious trad-
itions include taboos, the infringement of
which could incur the wrath of deities and
bring dire consequences (Laird, 2004).
For centuries, the fear of supernatural
retribution has protected many precious
trees. The attendant cultural internaliza-
tion and social regulation, expressed as
village sanctions, including punitive meas-
ures, have strengthened local enforcement
(Berkes, Colding and Folke, 2000).
In managing urban forests, outstanding
trees – whether or not associated with trad-
itional sanctity – are often given special
care. Among dozens of epithets used in the
literature, such trees have been labelled as
champion, monumental and heritage trees
(Jim, 2017a). There are clear indications of
the continued reverence attached to trees,
but the dilution of traditional taboos in
cities calls for substitute protection based
on statutory and administrative measures.
The impacts of urbanization
on heritage trees
Increasing urbanization by intensication
and sprawl has the potential to threaten
urban forests (FAO, 2016) and to deci-
mate the tiny but vital cohort of iconic
heritage trees. For example, subterranean
tree habitat is widely neglected. Heritage
trees in urban and peri-urban environ-
ments often suffer from the ill treatment
of soils, which could be inadvertent due
to misconceptions (Jim, 2005). Original
natural soils are commonly compacted,
added to, removed or polluted, and the
most valuable topsoil horizons – with
high organic matter content and nutri-
ent stock – are often degraded or lost.
Surface sealing and associated soil com-
paction can harm and restrict root growth.
Iconic trees attract many visitors, who
may damage soil structure and cause the
compaction or loss of topsoil; such trees
sometimes have literally been loved to
decline and demise. In dense cities, the
routine response to heavy foot trafc is
to install impermeable concrete, asphalt
or other paving materials, which causes
additional damage. Awareness needs to be
raised that soil problems have contributed
signicantly to poor tree health and long-
term deterioration.
Urban forest managers, as the modern
custodians of this natural-cum-cultural
heritage, are charged with ensuring the
long-term welfare of heritage trees in
urban and peri-urban environments. By
sharing research and practices, tailor-
made measures can be developed to
ensure the continued robustness and
survival of heritage trees. This article,
which draws on literature and extensive
field studies, focuses on such trees in
cities and their fringes with a view to
improving their conservation worldwide.
It evaluates designation yardsticks, surveys
notable management practices and certain
activities of citizens, and concludes with
lessons learned.
DESIGNATION AND TYPOLOGY
Table 1 shows the ten physical and cultural
criteria adopted in various jurisdictions
for the identication of heritage trees,
with three levels of significance. The
key physical tree dimensions are height,
crown spread and diameter at breast
height (American Forestry Association,
undated), which are measured in the
eld using accurate instruments such as
laser hypsometers. Trees that have crown
spreads wider than 30 m, are above 30 m
in height, or have diameters greater than
2 m at breast height are generally regarded
as landscape giants. There is a preference
for trees older than 100 years, and those
exceeding 300 years are widely rated as
exceptional.
Other criteria recognize crucial attrib-
utes such as tree performance,
1
ecological
function and scenic or landscape domi-
nance. Some trees vividly demonstrate
the outstanding traits of a species in form,
structural integrity or vigour. Veteran trees
accommodate assorted microhabitats,
offering complex micro-ecosystems
inhabited by diverse ora and fauna (Read,
2000). Cultural dimensions are expressed
1
“Tr ee performa nce” refers to genera l tr ee hea lth
and structural integrity.
TABLE 1. Designation criteria for the evaluation of heritage trees
Criterion Rating score
123
1 Tree height (m) < 15 15–30 > 30
2 Crown spread (m) < 15 15–30 > 30
3 Diameter at breast height (m) < 1 1–2 > 2
4 Tree age (yrs) < 100 100–300 > 300
5Tree performance Low Medium High
6Ecological function Low Medium High
7Scenic/landscape dominance Low Medium High
8Personality/event association Low Medium High
9Natural/cultural bequest Low Medium High
10 Spiritual/mythical connotation Low Medium High

Unasylva 250, Vol. 69, 2018/1
68
in the criteria “personality/event asso-
ciations” tied to local history; “natural/
cultural bequest”; and “spiritual/mythical
connotation”. For example, trees associ-
ated with personalities might be those
planted on the occasion of the coronation
of a king. Trees associated with events
could be those planted or designated to
commemorate an important event, such
as a battleground victory. Trees associated
with local beliefs might be those consid-
ered the abodes of spirits or deities with
mystical or religious connections. Some
trees are intimately linked to landmark
historical events or notable persons,
thereby bestowing social–cultural val-
ues (Blicharska and Mikusinski, 2014).
Trees planted by dignitaries on important
dates have commemorative signicance.
Others may be actively worshipped, as
evidenced by shrines, altars or associated
paraphernalia. Some trees grow spontane-
ously on articial structures such as old
buildings and masonry retaining walls
and in archaeological ruins. Specimens
of unusual size and form are likely to be
ecologically and culturally signicant
(Jim, 2013).
Heritage trees can be classied based
on site and tree characteristics to facilitate
understanding, management and conser-
vation. Figure 1 provides a typology of
tree sites based on seven criteria, each
with three states, that inuence habitat
quality and hence the past growth of a
given heritage tree and its prognosis. Site
origin may be remnant natural, emulated
natural or created articial, reecting the
degree of naturalness and habitat quality.
Site environs are characterized by building
density, which may impose microclimatic
stresses such as heat load and shading.
Within a site, the size of the belowground
space affects crown development. Soils
may be high-quality or degraded due to
human disturbance. The extent to which
the natural topsoil has been retained
affects tree growth. The site surface may
be open, or it may be sealed by imperme-
able materials (e.g. concrete), affecting
root development. Grade change – either
by burying existing soil with added soil or
by removing the original soil – is injurious
to roots (Jim, 2017b).
Figure 2 provides a typology of heri-
tage trees based on seven key attributes
(the photo on page 70 gives an indicative
typology for a tree in the Meiji Shrine in
Tokyo, Japan). Provenance is about whether
a tree is inherited from pre-urbanization
vegetation or planted after urban develop-
ment (or it could have been transplanted).
The decision to preserve a tree may have
been made consciously, with an accom-
panying protection and management plan,
or the tree may have survived by default.
The presence of companion trees could
indicate better habitat conditions than
those pertaining to solitary specimens.
Determining the relative age of trees can
help in identifying those veterans in need
of special care (Fay, 2002). The biomass
Site typology for heritage trees
Emulated
natural
Created
articial
Remnant
natural
1 Site origin
Low-density
built-up
High-density
built-up
Greeneld2 Site environs
Moderately
conned
Seriously
conned
Spacious
3 Belowground
space
Moderately
degraded
Badly
degraded
High-grade4 Soil quality
Partly lost Completely
lost
Largely intact5 Natural topsoil
Semi-
permeable Impermeable
Open soil6 Soil sealing
Raised LoweredOriginal7 Soil grade
1
Site typology for
heritag e trees in urban
and peri-urban settings

69
Unasylva 250, Vol. 69, 2018/1
structure can be evaluated as a function
of the live crown ratio (that is, the ratio
of the height of the crown containing live
foliage to the height of the tree) and soil–
root integrity,2 indicating the net outcome
of site history and contemporary factors.
The structural integrity of stems and roots
may have been compromised by natural
or human impacts.
EXEMPLARY MANAGEMENT
PRACTICES
People have been protecting and caring
for heritage trees since ancient times and
continue to do so today, often with little
or no government input. In cities, however,
heritage trees are usually managed by
urban forest administrations. The manage-
ment practices reviewed here are derived
from diverse sources (for the sake of
brevity, they are mostly unreferenced).
Some cities have established ofcial reg-
isters of heritage trees in printed or digital
form, together with the selection criteria
used. The information contained in such
registers varies from the bare minimum
(e.g. species and location) to detailed sur-
vey and assessment data, digital maps and
access guidelines (e.g. City of New York,
undated; Jim, 1994).
In some jurisdictions, trees in private
lands are excluded from the administrative
ambit and therefore may not benet from
systematic assessment, care and protection.
In cities experiencing rapid expansion and
redevelopment, such neglected trees are
prone to damage or felling – and residents
may not know what has been lost. Trees on
the grounds of private institutions, espe-
cially religious establishments, usually
receive a certain level of care, despite a
lack of ofcial input. For religious rea-
sons or because of taboos associated with
the harming of sacred trees, such trees
are less likely to be damaged by own-
ers, managers and visitors than trees on
other forms of non-public land. Because
religious grounds tend to persist in urban
landscapes, they are often valuable sites for
heritage trees. Their low-density, low-rise
built form and freedom from construction
works are conducive to tree preservation.
In contrast, residential and commercial
land uses are subject to urban renewal,
in situ intensication and inlling, all of
which can degrade site quality and cause
tree damage or removal.
Some cities have established comprehen-
sive heritage-tree databases, tree laws and
management agents to improve manage-
ment and conservation; such databases, if
continually updated, facilitate the timely
formulation of action plans. Some admin-
istrations assign sufcient resources and
well-trained professional and technical staff
to ensure appropriate tree care, and some
have active publicity and public-education
programmes that present information
in accessible forms. Such programmes,
2 That is, eld evidence showing that the soil in
the area embodying the tree roots has not been
disturbed or cut away.
Heritage tree typology
Inherited Cultivated
1 Tree
provenance
In situ Transplanted
2 Transplant
history
Conscious By default
3 Tree
preservation
Cultivated
neighbours Solitary
Natural
neighbours
4 Companion
trees
Mature Semi-matureVeteran
5 Relative
tree age
Medium
(60 –80%)
Low
(<60%)
High
(>80%)
6 Live crown
ratio
Moderately
restricted
Severely
restricted
Little
restriction
7 Soil grade
2
Tree typology for
heritag e trees in urban
and peri-urban settings

Unasylva 250, Vol. 69, 2018/1
70
including public lectures and guided eld
tours, disseminate relevant knowledge and
messages, raise awareness among citizens,
and increase public support for heritage-
tree maintenance and conservation.
Succinct, attractive information plaques
are installed at tree sites to convey conser-
vation messages. In addition to providing
basic information on the species, plaques
may include statements about the cultural-
historical background of a tree or site, its
association with local events and per-
sonalities, and interesting ecological and
ethnobotanical functions. Information on
connections with traditions, deities and
other supernatural objects is sometimes
included, together with problems affecting
tree health, arboricultural treatments, and
potential threats. In some jurisdictions,
QR codes are provided to direct interested
people to further web-based information.
Some cities have developed techniques
to arrest the decline of old or degraded
heritage trees. These focus on relieving
problems of soil compaction and the deg-
radation of soil structure, composition and
properties and on increasing the moisture-
holding capacity of soils and nutrient
supply. Soil treatments are restricted to
only a portion of sites to avoid shocking
the trees. Often, the site soil is loosened
to a prescribed depth by various means,
such as the use of air spades,
3
drilling
inclined bore holes, and opening narrow
radial trenches (Beijing District Standard,
2009). The poor site soil is replaced with
a soil mix enriched with mature compost.
Research is needed on soil improvement
techniques to arrest tree decline and boost
growth (Layman et al., 2016).
Heritage trees require a high standard
of arboricultural care, and inexperienced
or ill-informed tree management can have
detrimental impacts. Common mistreat-
ments include excessive or frequent branch
pruning, improper branch tipping, the pref-
erential removal of lower branches, and
aggressive crown reduction and thinning.
For veteran trees, an inadequate under-
standing of the multiple microhabitats they
provide for a diverse assemblage of ora
and fauna has led to overzealous sanitiza-
tion treatments (Woodland Trust, 2008).
3 Air spades are eld tools that use compressed
air to generate a supersonic air jet that can
blow away soil particles while retaining most
of the roots.
© C.Y. JIM
This old camphor tree (Cinnamomum
camphora) in the grounds of the Meiji
Shrine in Tokyo is venerated as a
wishing tre e. Note the open wo oden
frames installed below the tree
canopy for hanging wooden placards,
on which wishes are written. The
approximate typology of this tre e, as per
Figure 2, would be: 1) cultivated; 2) in situ;
3) conscious; 4) cultivated neighbours;
5) mature; 6) high; 7) little restriction

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Unasylva 250, Vol. 69, 2018/1
The proper management of heritage trees
requires knowledge of a wide range of
aspects – such as the tree’s ecology, growth
habits, microclimate, soil science, and cul-
tural signicance, and the threats posed by
the urban environment – and specialized
skills. To mitigate risks at sites with above-
average pedestrian trafc, a compromise
needs to be found between ecology and
safety (English Nature, 2000).
Outstanding trees affected by develop-
ment can sometimes be retained, given
sympathetic urban design. For example,
building footprints and road alignments
can be recongured or shifted to avoid
impacts on protected trees. Construction
activities near preserved trees can be
adjusted to minimize impacts, and precau-
tionary measures can be taken to protect
roots and stems. Future site conditions
should be designed to enable sustained
tree health, with sufcient good-quality
space to accommodate crown and root
expansions. Roadside heritage trees can
be protected from trenching damage by
diverting excavation alignments or by
adopting trenchless or no-dig techniques
(Jim, 2003).
Where circumstances do not allow
in situ preservation, transplanting may be
considered as a last resort. Transplanting
a large tree demands multidisciplinary
collaboration between tree experts and
engineers (Jim, 1995). Phased root pruning
is conducted well in advance. The root ball
should be large enough to accommodate
sufcient roots and strong and rigid enough
to prevent deformation by the moving and
lifting operations. The recipient site should
be chosen or prepared to match as closely
as possible the donor site in terms of above-
ground and soil conditions.
Advocates of trees in urban spaces have
tended to emphasize the environmental
and ecological benets but, increasingly,
the economic and social contributions of
trees are attracting research and com-
munity attention (Becker and Freeman,
2009). Recent studies have combined tree
evaluation and economic valuation to link
tree value more intimately with inherent
tree attributes (Jim, 2006). It is important
that the ndings of such studies are made
publicly available in accessible language
to increase community awareness of the
diverse roles played by heritage trees and
interest in their protection. Strong public
support for heritage trees will increase
the willingness of policymakers to assign
adequate funding and staff. In this way,
iconic heritage trees can play crucial roles
in rallying attention and support for urban
and peri-urban forestry.
© C.Y. JIM
This old Japanese cedar
(Cryptomeria japonica), situated
next to a path l eading to shrine s
in the Takao Mountains in
western Tokyo, is protected and
worshipped as a sacred tree

Unasylva 250, Vol. 69, 2018/1
72
Citizen endeavours
Many people living in urban environments
have considerable respect for trees due
to both tradition and modern environ-
mental education (Zhang et al., 2007),
and this can be harnessed to boost tree
protection efforts. Self-initiated citizens’
green groups have played pivotal roles in
protecting heritage trees by engaging com-
munities and raising public awareness and
knowledge (FAO, 2016). In such groups,
members are coached in tree assessment
techniques to become “citizen tree war-
dens” to participate in basic tree care. Most
importantly, they monitor site conditions
to prevent degradation and guard against
harm to heritage trees. Citizen tree war-
dens and green groups play important roles
in many cities by alerting governments,
non-governmental organizations and the
media to risks posed to heritage trees and
have launched many concerted tree-saving
operations. Good examples of such groups
include Big Trees in Bangkok, Thailand,
and the Conservancy Association in
Hong Kong, China, which alert citizens
to threats to urban trees and help prevent
their damage or removal. Overall, with
well-organized involvement, participation,
education and engagement, citizens can be
effective tree guardians and also partners
with governments in promoting green
urban spaces and nature conservation.
THE PROS AND CONS OF
WISHING TREES
In some places, there is a belief that
the deities or spirits residing in certain
heritage trees will respond benevolently to
people’s requests, and such trees have been
designated as wishing trees. This prac-
tice is probably a residual expression of
ancient polytheistic beliefs and associated
paganism and idolatry. Wishers seek good
fortune for themselves and their loved ones
in all sorts of personal and interpersonal
domains, such as romantic love, family
relationships, friendship, health, work
and study. Votive or token offerings are
transmitted to wishing trees in various
modes. Burning paper incense, candles and
joss sticks is a common ritual in East Asia.
Some cultures treat certain trees as living
temples and like to pray, sing and meditate
near them and to ambulate around them. In
Japan and the Republic of Korea, a com-
mon passive and non-intrusive approach is
to write wishes on small wooden placards
that are hung on racks near heritage trees
(see photo page 70). The placards are usu-
ally removed each day to provide space for
new ones. At some sites, visitors pay to
keep their placards in weatherproof glass
cabinets for longer periods.
Sometimes, intrusive or even damag-
ing actions are adopted to convey wishes
© C.Y. JIM
This century-old
Chinese banyan
(Ficus microcarpa)
was originally
designated as the
sacred (“deity of
the earth”) tree
protecting its Hong
Kong village from
harm but was
subsequently used
as a wishing tree.
The tree received
thousands of
paper offerings,
which were tied
to oranges and
thrown by visitors
to hang on the
branches, causing
considerable
damage. This mass
vandalis m was
stopped only after
a large branch fell,
injuring several
people

73
Unasylva 250, Vol. 69, 2018/1
from people to trees. In Western countries,
such actions include hammering nails, pins
or coins into tree trunks. Less injurious
methods are also used, such as tying cloth
or ribbons to branches, and irrigating trees
with alcoholic libations. Some people hang
material offerings on trees, such as apples,
meat, candy and cigars. These practices
are seldom adopted in Asia. In East Asia,
and especially on mainland China, people
write their wishes on pieces of paper which
are folded and tied onto small branches.
A more aggressive method of conveying
wishes to trees was invented in the 1990s
in a village in Hong Kong. Apparently
trying to boost sales, hawkers used string
to tie wish papers to oranges, and these
projectiles were thrown at a century-old
Chinese banyan (Ficus microcarpa) tree
in an attempt to lodge the “wishes” on it.
In the early 2000s, the tree was assaulted
daily with hundreds of oranges (with
wishes attached), and the ofcial tourism
organization promoted the practice to local
and overseas visitors. Many small branches
were broken. In removing the tokens so that
the tree could receive a fresh barrage each
day, the entwined strings were forcibly
pulled away, causing extensive damage
to foliage and branches and creating
numerous wounds open to pest and fungal
invasion. The daily cycles of attack and
dislodgement over several years seriously
enfeebled the tree. Eventually, in 2005, a
large branch fell and hurt several throw-
ers, whereupon the authorities stopped the
practice (Leisure and Cultural Services
Department, 2005). Unfortunately, the
practice has been mimicked in other cities
and religious establishments on mainland
China, damaging many heritage trees
(Huitu.com, 2017). Inexplicably, such
collective vandalism is often endorsed or
condoned by authorities.
LESSONS LEARNED
If a city can take excellent care of the
cream of its tree stock, its heritage trees,
it can inspire condence in its capacity to
care for all its urban and peri-urban forests.
The extent of care shown for heritage trees
also speaks volumes about the attitudes
of the community to nature and about
citizen welfare. From the above analysis,
the following recommendations can be
proposed to management authorities to
mitigate existing problems and improve
professional practice:
•
Heritage trees are a crucial part of
urban forests, and their in-depth
assessment, regular monitoring, and
high-order and specialized care is
warranted.
•
Local capacity to manage heritage
trees can be nurtured through the
education of high-level urban forest
managers and arborists.
•
A dedicated urban and peri-urban
forestry unit could be established in
government to ensure the implemen-
tation of recommended actions in a
timely and professional manner.
•
Statutory measures are essential
for supplementing administrative
approaches and ensuring sufcient
safeguards against the destruction of
heritage trees.
•
A well-maintained, detailed database
of heritage trees, and a regular and
systematic monitoring programme,
will enable the timely prognosis of
threats posed to heritage trees and
effective preventive care.
• It may be possible to save declining
heritage trees and prolong their safe
service life with dedicated rejuvena-
tion plans.
•
For long-term tree health, the qual-
ity of aboveground and belowground
habitats must be assiduously ensured
and acute and chronic stresses abated.
• The neglect of tree risk assessment,
which is particularly important for
the management of veteran heritage
trees in compact urban areas, requires
urgent attention.
•
Heritage trees should be transplanted
only as a last resort. It is technically
feasible, however, to move large
heritage trees without causing undue
harm or jeopardizing long-term
performance.
•
The special skills of heritage-tree care,
including pruning and the treatment
of veteran trees, must be mastered to
deliver high-calibre results.
•
Practices and activities that are harmful
to heritage trees must be averted at the
earliest possible stage, which requires
vigilance (for example through well-
informed citizens’ groups).
•
Ongoing, adequately funded research
is needed to study locally specic
issues affecting heritage trees and to
inform mechanisms for the effective
transfer of knowledge from research
to practice.
•
The economic valuation of heritage
trees can help raise awareness of the
benets such trees generate for soci-
ety and to muster support for urban
fo restry.
•
Green non-governmental organiza
-
tions can develop partnerships and
synergies with government and pri-
vate bodies to further the cause of
heritage trees. u
References
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value of old growth trees in Israel. Forest
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FAO FO RESTRY
Unasylva 250, Vol. 69, 2018/1
75
© SIMONE BORE LLI
75
Greener, cooler, healthier cities
The need for greener and healthier cities was highlighted in two
major re gio nal meetin gs on urban fo restry – Asia and the Pacic, and
Latin Ameri ca – in 2017. The two events explored th e benets of urban
trees and forests for the millions of people living in cities and megacities
in the two regions and their role in mitigating climate change.
Asia-Pacic Urban Forestry Meeting
The second Asia-Pacic Urban Forestr y Meeting, co-organized by
FAO, discussed and endorsed an action plan to help countries in
the region develop sound urban and peri-urban forest practices.
The meeting, which was held in Seoul, the Republic of Korea, on
13–15 September 2017, followed up on the rst Asia-Pacic Urban
Forestry Meeting, held in Zhuhai, China, in 2016. The rst meeting
culminated in the Zhuhai Declaration, a declaration of intent to
increase trees and forests in cit ies and to make cities gre ene r, cooler
and healthier. The regional plan of action launched at the second
meeting builds on the Zhuhai Declaration. It includes a set of robust
urban forestry actions to be implemented by countries to increase
the sustainability and resilience of urban development in the region.
More information: www.fao.org/asiapacic/news/detail-events/
en/c/1036873
Latin American and Caribbean Forum on Urban Forestry
The Latin American and Caribbean Forum on Urban Forestry,
Silviculture and Landsc ape Restor ati on for Urban For ests and Gre en
Areas, organized by FAO in collaboration with the Latin American
Development Bank, was held in Lima, Peru, on 7–9 June 2017.
Its purpose was to discuss how best to make cities in the region
greener, healthier and more sustainable and resilient in the face of
climate change.
More information: www.fao.org/peru/noticias/detail-events/es/c/
892705
To complement these regional initiatives, FAO is organizing, with
partners, the World Forum on Urban Forests, to take place in Mantova,
Italy, on 28 November–1 December 2018 (see the article on page 3
and the announcement on the inside front cover).
Sustainable wood for a sustainable world
Sustainable wood value chains that are environmentally friendly,
socially responsible and economically sound are an integral part
of sustainable landscapes and key to making progress towards the
Sustainab le Development Goals (SDGs), accor din g to the experts who
met at the Sustainab le Wood for a Sust ain abl e World global meet ing
at FAO headquarters in Rome on 31 October–1 November 2017.
The meet ing , which was attended by mo re than 100 delegates from
40 countries, was organized by FAO and its Advisory Committee
on Sustainable Forest-based Industries in collaboration with the
Center for International Forestry Research, the Finance Alliance for
Sustainable Trade, the International Tropical Timber Organization,
the World Bank and the World Wildlife Fund.
Sustainab le wood value ch ains and pro duc ts ar e especi ally relevant
to SDG 8 (decent work and economic growth), SDG 12 (responsible
Cities worldwide are increasingly aware that trees and
forests make cities greener, cooler and healthier

Unasylva 250, Vol. 69, 2018/1
76
consumption and production), SDG 13 (climate action) and SDG 15
(life on land). Meeting participants agreed that, to enhance local
liveli hoo ds, there is a need to conne ct gl oba l, regional an d loc al value
chains and to diversify forest products beyond wood to make effective
use of “baskets of value chains”. Sustainable forest management
was repeatedly cited as a signicant component of sustainable
landscape management.
The meeting emphasized the crucial role of sustainable wood
value chains in mitigating climate change through carbon storage in
standing forests and harvested wood products and the substitution
of fossil-based raw materials and products. The contribution of
wood to climate-change mitigation in the construction sector was
also highlighted.
Increasing investments to promote sustainable wood value chains
requires the assessment of investment barriers and opportunities
along value chains and the securitization and monetization of the
full range of forest products and services. The creation of a virtual
multistakeholder investment promotion facility would help tailor
nance to support sustainable wood value chains.
The global meeti ng co nst ituted the star t of an init iative by FAO an d
partners to strengthen the role of sustainable wood value chains in
sustainable development.
FAO’s regional forestry commissions
Established by the FAO Conference between 1947 and 1959, the six
regional forestry commissions represent FAO’s institutional presence
in forestry at the macro-regional level worldwide. The commissions
convene every two years to bring together heads of forestry and
experts in the six major regions worldwide to address policy and
technical issues in their respective areas of inuence.
In rep orting their inputs and re com men dat ion s to the FAO Commit tee
of Forestry (COFO), which is the biennial global forum for all forestry
issues, and to the United Nations Forum on Forests (UNFF), the
regional forestry commissions function as important liaison institutions
between country-level and global issues. They also help identify
regional tr end s, needs and specic areas of in ter vention that should
be considered in a well-designed global plan of action for forestry.
The regional forestry commissions contribute to dialogues with
other regional forestry institutions and organizations, and most have
technical working groups or subregional chapters, which, among
other things, implement projects that benet from collaboration
among countries in the region.
Of the most rece nt round of re gional for estry commi ssi on me etings,
ve had taken place by February 2018 (with the sixth planned for
March 2018). It has addressed the following items:
• a study on sustainable forestry for food security and nutrition
conducted by the Committee on World Food Security High-level
Panel of Exper ts;
• input for the upcoming Global Forest Resources Assessment
2020 and streamlining forestry reporting;
• outcomes of the 22nd Conference of the Parties (COP) to the
United Nations Framework Convention on Climate Change,
COP 13 of the Convention on Biological Diversity, the 12th meeting
of the UNFF, and other institutional global fora; and
• a new strategic document for FAO in forestry, as well as input
to FAO governance.
Other imp ortant issues di scu sse d at one or mor e com mis sio n meet-
ings included gender; social protection; community-based forestry and
farmer organizations; communication in forestry; urban forestry; forests
in landscape restoration; and initiatives to combat desertication.
Regional in put s on these an d other issues are es sential for ad apting
strategies, policies and projects to the characteristics and needs of
each region.
The ofcial reports of the regional forestry commission meetings
will be presented at the 24th Session of COFO, scheduled to take
place at FAO headquarters in Rome in July 2018.
© FAO/MARCO LONGAR I
An ofcer inspects
rough-sawn boards at
Dakar port, Senegal.
Sustainable wood
value chains that are
environmentally friendly,
socially responsible and
economically sound are
crucial for making progress
towards the Sustainable
Development Goals

WORLD OF FORESTRY
77
Unasylva 250, Vol. 69, 2018/1
United Nations adopts Strategic Plan for Forests
The rst-ever United Nations (UN) Strategic Plan for Forests,
adopted by the UN General Assembly on 27 April 2017, provides an
ambitious vision for global forests in 2030. The plan features a set
of six Global Forest Goals and 26 associated voluntary, universal
targets to be reached by 20 30. It is designed to serve as a reference
framew ork for the fo rest-relat ed work of the UN system and to fost er
enhanced coherence, collaboration and synergies among UN bodies
and partners. The plan also serves as a framework to enhance
the coherence and guide and focus the work of the International
Arrangement on Forests and its components. The six Global Forest
Goals are:
1.
Reverse the loss of forest cover worldwide through sustainable
forest management, including protection, restoration,
afforestation and reforestation, and increase efforts to prevent
forest degradation and contribute to the global effort of
addressing climate change.
2.
Enhance forest-based economic, social and environmental
benefits, including by improving the livelihoods of forest-
dependent people.
3. Increase signicantly the area of protected forests worldwide
and other areas of sus tai nab ly managed for ests, as wel l as the
proportion of forest products from sustainably managed forests.
4.
Mobilize signicantly increased, new and additional nancial
resources from all sources for the implementation of sustainable
forest management and strengthen scientic and technical
cooperation and partnerships.
5.
Promote governance frameworks to implement sustainable
forest management, including through the UN Forest Instrument,
and enhance the contribution of forests to the 2030 Agenda for
Sustainable Development.
6.
Enhance cooperation, coordination, coherence and synergies on
forest -related issues at all levels , inc luding within the UN sys tem
and across member organizations of the Collaborative
Partnership on Forests, as well as across sectors and relevant
stakeholders.
One of the targ ets in th e pla n is to increase forest area by 3 percent
worldwide by 2030, which would be an increase of 120 million
hectares. The plan builds on the vision of the 2030 Agenda for
Sustainable Development and recognizes that real change requires
decisive, collective action, within and beyond the UN system.
PHOTO BY IISD/PETER WOOD (ENB.IISD.ORG/FORESTRY/UNFF/WGSS/20JAN.HTML)
Co-Chairs Mohammad
Ali Zarie Zare, Iran
(Islamic Republic of),
and Hans Hoogeveen,
the Netherlands, shake
hands at the end of the
UNFF Working Group
and Special Session.
The session was held
on 16–20 January 2017
at UN headquarters in
New York, USA, to, among
other things, develop
a proposal for a UN
strategic plan on forests
for 2017–2030

78
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Reducing Inequality in a Turbulent World:
Scaling-up Strategies to Secure Indigenous,
Community, and Women’s Land Rights
More than 300 people from 58 countries gathered in Stockholm,
Sweden, on 4–5 October 2017 to raise awareness of community
land rights as a pre req uisite for decr eas ing inequalit y and deli ver ing
on global goals; assess the status of promising instruments to
secure community rights; and encourage greater action, support
and commitment from key stakeholders. Participants hailed from
indigenous and community organizations, the private sector, civil
society and governments. The conference was co-organized by the
Rights and Resources Initiative, Sida, the Stockholm Environment
Institute, the Swedish International Agriculture Network Initiative,
and the International Foundation for Science.
This confer enc e was the third in a series , following simil ar meetings
in Interlaken and Bern, Switzerland, in 2013 and 2015. The ser ies is
designed to take stock of the global state of indigenous, community
and rural wom en’s land rights , rai se awaren ess of the importance of
these rights, catalyse new partnerships, and develop a shared path
forward for scaling up the recognition of rights.
Resear ch la unc hed on the eve of the Sto ckh olm conference fou nd
that 61 percent of land-based conicts between companies and
communities since 2001 are unresolved. Securing community and
indigenous land rights is vital for mitigating and preventing these
devastating conicts, achieving the Sustainable Development Goals
and the commitments of the Paris Agreement, and ensuring peace
and justice.
Three strategy sessions at the co nference (on rur al an d indigenous
women’s rights and leadership in collective lands; strategies and
mechanisms to scale up implementation from the local to the national
level; and connecting and leveraging international support structures
to advance indigenous and community land rights) developed action
plans to increase recognition of community land rights. All sessions
included speakers from the private sector, whos e rec ommendations
were highlighted in a plenary session on the second day of the
conference.
For the rst time, the conference included an “innovation zone”,
which highlighted the use of technology and other innovative
strategies to secure rights.
There is growing recognition of the importance of community land
rights, both as a matter of human rights and as a crucial solution to
global problems, including inequality and climate change. There is
also unprecedented momentum and growing commitment from all
sectors to secure and resp ect thes e rights. Conf erence participants
identied ways to conn ect and levera ge global and gra ssr oot s effort s
to drive change.

BOOKS
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Helping countries assess their standing forests
Voluntary gu idelines on natio nal forest monitorin g. FAO. 2017. Rome.
ISBN 978- 92-5-109619-2.
Es tabli shing an d runni ng a nat ional forest mo nitor ing system (NFMS)
is a complex scientic-technical process and an organizational and
institutional challenge. An NFMS exercise has a direct link to policy
because it informs management and decision makers about the
sustainable use of forest resources and the efcient protection and
conservation of forest ecosystems. Accordingly, an NFMS supports
governments in fullling their obligations to continually develop,
monitor and report on forest resources, which may include trees
outside forests as well as other land-cover classes. The aim of
these voluntary guidelines is to assist in the creation and operation
of NFMSs. They include good-practice principles, guidelines and a
general framework. The document also incorporates a set of decision-
support tools for planning and implementing a multipurpose NFMS
gr oun de d in na tiona lly app ropri ate and sc ienti call y sound practi ce,
taking into consideration domestic information needs and reporting
requirements.
Available online: www.fao.org/3/a-i6767e.pdf
Also available online in:
Arabic – www.fao.org/3/a-i6767a.pdf
Chinese – www.fao.org/3/a-i6767c.pdf
French – www.fao.org/3/a-i6767f.pdf
Russian – www.fao.org/3/a-i6767r.pdf
Spanish – www.fao.org/3/a-i6767s.pdf
Increasing food security with sustainable woodfuel
Sustaina ble woodfuel for foo d security. A smart cho ice: green, renewable and
affordable. FAO. 2017. Rome. ISBN 978- 92-5-109962-9.
Food insecurity and a high dependence on woodfuel as a primary
cooking fuel are characteristics common to vulnerable groups of
people in developing regions worldwide. With adequate policy
and legal frameworks in place, however, woodfuel production and
harvesting can be sustainable and a main source of green energy.
Mo reover, the wi despr ead availa bilit y of woodf uel, and the enormo us
market for it, presents opportunities for employment and sustainable
value chains, providing additional reasons for promoting this energy
source. This paper explains how sustainable woodfuel is linked closely
to food security and provides insights into how the linkages could be
strengthened at all stages of woodfuel production, trade and use.
Available online: www.fao.org/3/a-i7917e.pdf

80
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Mainstreaming gender in forest policies in Kosovo
Gender, rural live lihoods and forest ry: assessment of gen der issues in Kosovo’s
forestry. FAO. 2017. Rome. ISBN 978-9 2-5-109797-7.
The main purpose of the research reported in this publication is to
identify and analyse the role of women and men in the forest sector
in Kosovo and their ownership and use of forests. The report also
analyses gender issues within the institutional, policy and legal
framework that governs forest management in Kosovo and makes
recommendations on how to mainstream gender in forest policies.
The research is part of a project titled, “Support to implementation
of the forest policy and strategy in Kosovo” (GCP/KOS/005/FIN),
funded by the Government of Finland, which aims to increase the
forest sector’s contribution to the national economy through the
su stain able us e of fo rest re sourc es, tak ing int o accou nt mu ltipu rp ose
forestry, the economic, social and environmental benets of forests,
and the sector’s contributions to the mitigation of climate change.
The study shows that women have limited access to decision making
an d informat ion com pa red with men . Rur al co mmunities – especia lly
women – identify high unemployment as the main obstacle they face.
The report demonstrates the interests of rural women in improving
their skills in the collection, processing and marketing of non-wood
forest products. Consequently, the report shows the importance of
improving women’s access to information, capacity development
and decision making. It concludes by emphasizing that non-wood
forest products have strong potential for reducing food insecurity
and poverty in the study regions, particularly when both women and
men are supported effectively.
Available online: www.fao.org/3/a-i7421e.pdf
Also available online in:
Albanian – www.fao.org/3/i7421sq/I7421SQ.pdf
Serbian – www.fao.org/3/i7421sr/I7421SR.pdf
What do zero-deforestation commitments mean
for forestry?
Potential im plications for th e forest industry of c orporate zero-defo restation
commitm ents. Discussi on paper prepared for th e 58th Session of the FAO Advi sory
Committee on Sustainable Forest-based Industries. 2017. FAO. Rome.
This paper analyses the implications for the forest industry of zero-
deforestation commitments made by consumer-goods customers
and nanciers and the benets that could arise, and it makes
recommendations to enable the forest industry to take advantage
of the benets and minimize the risks. The paper, which addresses
recommendations made by the FAO Advisory Committee on
Sustainable Forest-based Industries, provides background information
on the zero-deforestation movement, building on earlier work by the
Advisory Committee and FAO.
Available online: www.fao.org/3/a-i8042e.pdf

81
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Improving energy access for displaced people
in Uganda
Rapid woo dfuel assessment: 2017 baseli ne for the Bidibid i settlement, Ugan da.
2017. FAO & United Na tions High Com missioner for R efugees (UNHCR). 2017.
Rome and G eneva, Switzer land. ISBN 978- 92-5-109947-6 (FAO).
Ug anda is host to mo re than 1 milli on refug ees who have ed fam ine ,
conict and insecurity in the neighbouring countries of Burundi, the
Democratic Republic of the Congo and South Sudan. The recent
inux of refugees from South Sudan prompted one of Uganda’s
most severe humanitarian emergencies and led to the establishment
of the Bidibidi settlement in Yumbe District in August 2016. The
settlement is now the world’s largest refugee-hosting area, with
272 206 refugees settled on a land area of approximately 250 km2
in a total assigned area of 798 km
2
; the settlement constitutes
more than half the population of the host district. The settlement
has increased pressure on the environment due to tree felling for
settlement establishment and to meet ongoing household demand
for woodfuel for cooking and heating.
FAO and UNHCR initiated a joint rapid woodfuel assessment
in March 2017 to determine woodfuel supply and demand in the
area. The assessment had three components: 1) an assessment of
woodfuel demand; 2) an assessment of woodfuel supply; and 3) the
identication of interlinkages, gaps, opportunities and alternative
scenarios. Data and information were obtained through a desk review
of existing documents, eld sur veys and remote-sensing analysis.
Am ong oth er ndi ngs, th e repor t estim ates th at 12–15 perce nt of the
total land area of the Bidibidi settlement would need to be planted
with fast-growing species to provide a sustainable woodfuel supply.
Each household would need to dedicate a minimum woodlot area of
50 m × 50 m exclusively to growing wood for energy.
Available online: www.fao.org/3/a-i7849e.pdf
The potential of agroforestry for landscape
restoration
Agroforestr y for landscape rest oration: exploring the p otential of agrofores try
to enhanc e the sustainabili ty and resilience o f degraded landsc apes. 20 17.
A. Hillb rand, S. Borell i, M. Conigliar o & A. Olivier. Rome, FAO.
Agroforestry has considerable potential for restoring degraded
forests and agricultural lands and thereby contributing to landscape
restoration, but constraints limit its adoption. This brief makes the
following key points:
• Agroforestry can provide many ecosystem services. It is a suitable
tool for land sca pe re storation be cau se it can enhance phys ica l,
chemical and biological soil characteristics, thereby increasing
soil fertility, controlling erosion and improving water availability.
• Agroforestry systems that provide permanent tree cover can be
valuable forest and landscape restoration options, especially in
initiatives in which neither natural forest restoration nor full sun
crops are viable.
• Agroforestry can enhance livelihoods in rural communities by
providing a variet y of food, fodder and tree products, which
increase food and nutrition security, generate income and
alleviate poverty.
• The restoration of degraded landscapes using agroforestry can
increase the resilience of communities to shocks, including
drought and food shortages, and help mitigate climate change.
• The widespread uptake of agroforestry requires an enabling
legal and policy environment that guarantees rights to – and
ownership of – trees and land, provides farmer s wit h inc ent ives,
promotes investment, and facilitates the marketing of agroforestry
products.
Available online: www.fao.org/3/b-i7374e.pdf
Also available online in Spanish: www.fao.org/3/b-i7374s.pdf

82
Unasylva 250, Vol. 69, 2018/1
Protecting forest-dependent communities
Social pro tection for forest- dependent com munities. Polic y brief. 2017. N. Tirivaye,
O. Rodrig uez, T. Juvenal & Q iang Ma. Rome, FAO.
Forest-dependent communities are usually located in remote rural
areas characterized by low levels of market development and poor
access to public goods and social services. They must deal constantly
wi th the co nsequ ences of market fai lure and are pa rt icula rly expose d
to risks and repeated shocks. A wide range of environmental,
economic, health-related, demographic, social and political factors
are key sources of vulnerability in these communities.
Since the imp leme ntation of FAO’s ve new Strategic Objectives,
social protection has become an important area of focus for the
Organization. This policy brief, developed by FAO in collaboration
with the United Nations University–Maastricht Economic and Social
Research Institute on Innovation and Technology, uses a global
literature review and country case studies in Burkina Faso, China
an d Ugand a to ex plore the need fo r more so cial pr otect ion for fo res t-
dependent communities. Among other things, the brief recommends
the inclusion of environmental and poverty-alleviation objectives in
social protection and forestry interventions and raising awareness
of the potential synergies between them.
Available online: www.fao.org/3/a-i7008e.pdf
The role of smallholder forest organizations in
climate-change mitigation and adaptation
Smallho lder forest produce r organizations in a cha nging climate. 2017. Forest and
Farm Facili ty. Rome, FAO.
National organizations and networks of smallholder forest producers
play important roles in climate-change mitigation and adaptation,
spanning political and practical action. Innovative and successful
climate action builds on the strengths of each organization and
harnesses the support of the membership base and organizational
alliances in multi-actor networks.
This publication summarizes the ndings of a review of the innovative
ways in which smallh ol der forest pr oduce r organ izati ons in developing
countries are contributing to climate-change mitigation and adaptation.
The review was carried out by the Finnish Agri-Agency for Food
and Forest Development and the Finnish Environment Institute in
collaboration with the Forest and Farm Facility.
The Forest and Farm Facility is a partnership between FAO,
the International Institute for Environment and Development, the
International Union for Conser vation of Nature, and AgriCord.
Available online: www.fao.org/3/a-i7404e.pdf

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Unasylva 250, Vol. 69, 2018/1
FAO’s approach to climate change
FAO strategy on cli mate change. 2017. Rome, FAO.
Three outcomes frame FAO’s strategy on climate change:
1.
Enhanced capacities of Member Nations on climate change
through FAO leadership as a provider of technical knowledge
and expertise.
2. Improved integration of food securit y, agriculture, forestry and
sheries in the international agenda on climate change through
reinforced FAO engagement.
3.
Stre ngt hen ed co ord ination and de livery of FAO’s work on cli mate
change.
The strategy on climate change sets FAO on a path to deliver on
the Sustainable Development Goals (SDGs), particularly SDGs 1, 2
and 13. In operational terms, it is an integral part of FAO’s Strategic
Frame wor k, Me diu m Term Plan, an d Pro gramm e of Work an d Budge t.
The strategy will be implemented through a plan of action designed
to strengthen FAO’s existing capacities, especially in decentralized
ofces, and it sets out the results to be delivered by FAO through its
Strategic Programmes.
Available online: www.fao.org/3/a-i7175e.pdf
Also available online in:
French – www.fao.org/3/a-i7175f.pdf
Spanish – www.fao.org/3/a-i7175s.pdf
Investing in trees to improve health
Funding tree s for health: an analysis of  nance and policy ac tions to enable tree
planting f or public health. R . McDonald, L. A ljabar, C. Aubucho n, H.G. Birnbaum,
C. Chandle r, B. Toomey & J. Daley, et al. 2 017. Arlington, USA, The Nature
Conservancy.
Every year, up to 4 million people die worldwide as a result of air
pollution, which has lifelong impacts on people’s health through
ailments such as asthma, cardiac disease and stroke. Each summer,
thousands of unnecessary deaths result from heatwaves in urban
areas. Studies have shown that trees are a cost-effective solution for
both these challenges, but investment in urban forestry is perpetually
underfunded.
This report examines the link between trees and public health, which
recent science has shown is robust and economically signicant.
One way to overcome the funding barrier for urban forestry, say the
authors, is to more closely link the goals and funding of the health
sector with the goals and funding of urban forestry agencies. The
authors urge all cities to explore ways of creating links between the
he alth se ctor an d urban fo res tr y agenc ies, us ing one of the pot ent ial
models discussed in the report.
Available online: http://tinyurl.com/ydauygzn

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Creating sustainable urban environments
Routled ge handbook of urban f orestry. 2017. F. Ferrini,
C.C. Konijnendijk van den Bos ch & A. Fini. Abin gdon, UK, Rout ledge.
ISBN: 9781138647282 (ha rdback); 9781315627106 (ebook)
More than half the world’s population now lives in cities. Creating
sustainable, healthy and aesthetic urban environments is therefore
a major policy goal and research agenda. This comprehensive
handbook provides a global overview of the state of the art and
sc ience of urban fo res tr y. It describ es the multi pl e rol es and ben ets
of urban green ar eas in gener al and the sp ec ic rol e of tr ees; reviews
the various stresses experienced by trees in cities and tolerance
mechanisms, as well as cultural techniques for either preconditioning
or alleviating stress after planting; and outlines the sound planning,
design, species selection, establishment and management of urban
trees. The handbook shows that the close involvement of local urban
communities who benet from trees is key to success.
Available for purchase at: www.routledge.com/Routledge-Handbook-
of-Urban-Forestry/Ferrini-Konijnendijk-van-den-Bosch-Fini/p/
book/9781138647282

© SIMONE BORELLI
Guidelines
on urban and
peri-urban forestry
A globally applicable guide to developing forests
that will meet the present and future needs of
cities for forest products and ecosystem services
by Fabio Salbitano, Simone Borelli, Michela Conigliaro
and Yujuan Chen
FAO Forestry Paper No. 178
Available in English, French and Spanish:
English: www.fao.org/3/a-i6210e.pdf
French: www.fao.org/3/a-i6210f.pdf
Spanish: www.fao.org/3/a-i6210s.pdf
Namsan Park,
Seoul, Republic of Korea

Unasylva@fao.org
www.fao.org/forestry/unasylva
I8707EN/1/02.18
ISBN 978-92-5-130383-2
9789251 303832
ISSN 0041-6436