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Lightning Fires in a Brazilian Savanna National Park: Rethinking Management Strategies

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Fire occurrences and their sources were monitored in Emas National Park, Brazil (17°49′–18°28′S; 52°39′–53°10′W) from June 1995 to May 1999. The extent of burned area and weather conditions were registered. Forty-five fires were recorded and mapped on a GIS during this study. Four fires occurred in the dry winter season (June–August; 7,942 ha burned), all caused by humans; 10 fires occurred in the seasonally transitional months (May and September) (33,386 ha burned); 31 fires occurred in the wet season, of which 30 were caused by lightning inside the park (29,326 ha burned), and one started outside the park (866 ha burned). Wet season lightning fires started in the open vegetation (wet field or grassy savanna) at a flat plateau, an area that showed significantly higher fire incidence. On average, winter fires burned larger areas and spread more quickly, compared to lightning fires, and fire suppression was necessary to extinguish them. Most lightning fires were patchy and extinguished primarily by rain. Lightning fires in the wet season, previously considered unimportant episodes, were shown to be very frequent and probably represent the natural fire pattern in the region. Lightning fires should be regarded as ecologically beneficial, as they create natural barriers to the spread of winter fires. The present fire management in the park is based on the burning of preventive firebreaks in the dry season and exclusion of any other fire. This policy does not take advantage of the beneficial effects of the natural fire regime and may in fact reduce biodiversity. The results presented here stress the need for reevaluating present policies and management procedures concerning fire in cerrado conservation areas.
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Lightning Fires in a Brazilian Savanna National Park:
Rethinking Management Strategies
MA
´RIO BARROSO RAMOS-NETO
VA
ˆNIA REGINA PIVELLO*
Departamento de Ecologia, Instituto de Biocieˆ ncias
Universidade de Sa˜ o Paulo
Rua do Mata˜o
Travessa 14, Sa˜ o Paulo, S.P., Brazil 05508-900
ABSTRACT / Fire occurrences and their sources were moni-
tored in Emas National Park, Brazil (17°49–18°28S; 52°39
53°10W) from June 1995 to May 1999. The extent of burned
area and weather conditions were registered. Forty-five fires
were recorded and mapped on a GIS during this study. Four
fires occurred in the dry winter season (June–August; 7,942
ha burned), all caused by humans; 10 fires occurred in the
seasonally transitional months (May and September) (33,386
ha burned); 31 fires occurred in the wet season, of which 30
were caused by lightning inside the park (29,326 ha burned),
and one started outside the park (866 ha burned). Wet season
lightning fires started in the open vegetation (wet field or
grassy savanna) at a flat plateau, an area that showed signifi-
cantly higher fire incidence. On average, winter fires burned
larger areas and spread more quickly, compared to lightning
fires, and fire suppression was necessary to extinguish them.
Most lightning fires were patchy and extinguished primarily by
rain. Lightning fires in the wet season, previously considered
unimportant episodes, were shown to be very frequent and
probably represent the natural fire pattern in the region. Light-
ning fires should be regarded as ecologically beneficial, as
they create natural barriers to the spread of winter fires. The
present fire management in the park is based on the burning
of preventive firebreaks in the dry season and exclusion of any
other fire. This policy does not take advantage of the beneficial
effects of the natural fire regime and may in fact reduce biodi-
versity. The results presented here stress the need for reevalu-
ating present policies and management procedures concern-
ing fire in cerrado conservation areas.
There is a consensus that fire has been occurring in
tropical savannas for thousands of years, shaping the
landscape and selecting for adapted flora and fauna. It
has also been accepted that ancient fires were caused by
natural events, mostly lightning, but also by volcanic
activity and friction between rocks. Nevertheless, after
humans came to gather in social groups, they became
the main cause of wildfires, greatly increasing the fire
frequency and changing fire regimes, from cool wet-
season fires to more intense dry-season fires (Komarek
1972, Edwards 1984, Coutinho 1990, Goldammer 1993,
Pyne 1993, Whelan 1995).
However, the belief that almost all tropical fires at
present are anthropogenic has not been adequately
demonstrated. Lightning fire outbreaks are poorly doc-
umented in tropical ecosystems, although there are
some records (Tutin and others 1996, Middleton and
others 1997). In Brazil, it was probably this lack of
recorded fire strikes that led to the opinion that light-
ning fires are rare in cerrados, the Brazilian savannas.
As Soares (1994) states “in cerrados...lightning might
even be an important cause for fires; however, studies
to confirm or to reject this hypothesis do not exist.”
The cerrado biome is the second largest realm in
Brazil, occupying over 1.8 million km
2
on the Brazilian
Central Plateau, at altitudes from 300 to 1,000 m above
sea level (Ab’Saber 1971). Although patches of forest
and grassland forms appear in the cerrado landscape, it
is dominated by savanna forms, in a gradient from open
grassy to woodland savannas. The more open the sa-
vanna structure, the more fire prone it is. On the other
hand, forest patches are not fire prone and only burn
when fire is intense.
The tropical humid climate in the cerrado region,
with a dry winter (3–6 months) and a wet summer,
imposes a strong seasonality to the vegetation, espe-
cially grasses, which dry out in the winter. At this time
of the year, cattle grazers used to burn cerrados to
promote grass regrowth and to supply palatable forage
to cattle. Subsistence farmers also used to burn arable
areas to prepare the land for cultivation in the wet
season. Therefore, cerrados managed in these ways
(almost all, except the natural reserves) sustain little
fuel to be burned by natural lightning fires in the next
wet season.
Hence, especially because of the management that
humans apply to cerrados, the burning season runs
from May to September, when the herbaceous vegeta-
KEY WORDS: Wildfire; Lightning; Brazilian savanna; Cerrado; Fire man-
agement; Emas National Park
*Author to whom correspondence should be addressed.
DOI: 10.1007/s002670010124
Environmental Management Vol. 26, No. 6, pp. 675– 684 ©2000 Springer-Verlag New York Inc.
tion is dry and more flammable, and fire spreads easily
from farmlands to natural areas. Early fires in May–June
are usually cool fires and burn the area patchily as the
vegetation still has high water content. As the dry sea-
son continues the curing status of the grass layer in-
creases and fire intensity also tends to increase. Fire
outbreaks peak by the end of the dry season (July–
August) (Coutinho 1990, Pivello 1992, Mistry 1998). In
the early wet season (September–October), fire occur-
rences decrease, although the vegetation is still able to
carry a fire (H. S. Miranda, personal communication).
Present-day discussion on the causes of wildland
fires, a subject explored since the 1970s (Komarek
1972, Edwards 1984), is not only a matter of conjecture;
it may be important to management approaches and
policies for conservation areas. Yet, little concern given
to the natural fire dynamics in Brazil, and the miscon-
ceptions about fire effects in natural environments led
the governmental sectors responsible for nature con-
servation to reject any fire in cerrado conservation ar-
eas, either natural or prescribed. The environmental
legislation, although very conservative, has permitted
the use of fire since 1989 for managing nature reserves
(Federal Decree No. 97635 from 10 April 1989) but, in
fact, decision-makers in the governmental body rarely
allow fire management in parks and reserves, even
though it can be a very useful and cheap management
tool.
Several environmental benefits may be brought by
fire in savannas, especially the stimulus to nutrient
recycling and to sprouting, fruiting, and seeding of
several plant species; it also increases the vigor and
palatability of a number of herbaceous species. Differ-
ent fire regimes (fire type, frequency, intensity, and
season) may favor distinct groups of species or may
consume more or less intensively the accumulated fuel
(Warming 1908, Coutinho 1980, 1982, 1990, Kruger
1984, Christensen 1985, Pivello 1992, Pivello and
Coutinho 1992, 1996, Whelan 1995, Pivello and Norton
1996). Such fire outcomes may result in management
ends, as wildfire control, food supply to native fauna,
weed control, and the maintenance of biodiversity and
ecological processes (Pivello 1992, Pivello and
Coutinho 1996, Pivello and Norton 1996).
As fire consumes the fuel, burned patches may act as
firebreaks to unburned areas and management burn-
ings can be used to avoid the spread of wildfires. Still, a
savanna landscape formed by a mosaic of unburned
patches and patches burned at different time intervals
is able to maintain a great variety of both sun-loving
fire-prone species and those from woodland savanna.
To achieve these goals, prescribed fires are used in
parks of diverse ecosystems worldwide as a management
tool, for example, in the North American Yellowstone
and Everglades national parks and in the Australian
Kakadu and Uluru national parks, among many others
(Saxon 1984, Parsons and others 1986, Schullery 1989,
Australian National Parks and Wildlife Service 1991,
Conroy and others 1997, Russel-Smith 1997).
In Brazilian protected areas, where an antifire policy
prevails, the consequence has been the occurrence of
periodic and severe wildfires, when fuels accumulate
and fire becomes inevitable, threatening animals and
humans. In Emas National Park and Chapada dos Vea-
deiros National Park, for example, severe fires occur
every 3–4 years (Redford 1985, Pivello 1992, 1996, Piv-
ello and Coutinho 1992, Franc¸a and Setzer 1997). Se-
vere wildfires in Emas National Park occurred in 1975,
1978, 1985, 1988, 1991, and 1994 and burned 74–93%
of the 132,133 ha of the park, killing a number of
vertebrates (I.B.D.F. 1981, Redford 1985, Silveira and
others 1996, Franc¸a and Setzer 1997). Furthermore,
the critical problem of invasions of alien grasses in
cerrados (Pivello et al. 1999a, 1999b) could, in some
cases, be controlled by low-intensity prescribed fires
(Pivello 1992, Pivello and Norton 1996).
The objective of this study is to demonstrate the
importance of lightning fires in the cerrados and to
emphasize the need to consider the beneficial effects of
these fires in management strategies. It is also impor-
tant to stress that we are justifying the use of prescribed
fires to manage savannas, and not tropical forests, as
the functioning and dynamics of these ecosystems are
totally different; as a rule, fire seriously damages trop-
ical forests (see Nepstad and others 1999).
The Study Area
Emas National Park is located in the core region of
the cerrado biome, the Brazilian savanna, in the SW of
Goia´s State, Central Brazil (17°49–18°28S and 52°39
53°10W) (Figure 1). It is the largest (132,133 ha) and
most important protected cerrado area, because of its
diverse flora and fauna (I.B.D.F. 1981, Redford 1987).
In this park, cerrado fauna is abundant and easily ob-
served. Several threatened species, including the giant
armadillo (Priodontes maximus), giant anteater (Myrme-
cophaga tridactyla), pampa cat (Felis colocolo) and puma
(Felis concolor), still occur there (Redford 1983,
Machado and others 1998).
Regional climate is tropical and humid, with wet
summers and dry winters (June–August), typical of sa-
vannas (zonobiome II, according to Walter and Lieth)
(Walter 1971). Annual rainfall ranges from 1,200 to
2,000 mm (Franc¸a and Setzer 1997, and this study),
concentrated from October to March (Figure 2a). Ac-
676 M. B. Ramos-Neto and V. R. Pivello
cording to the rainfall and soil water regime, May and
September are considered transitional months, since
they represent, respectively, the end and the onset of
the rainy season (Figure 2). Frost is expected every
winter, in June and/or the beginning of July.
Three quarters of Emas National Park consist of flat
tableland, 820888 m in elevation; the remaining area
consists of hilly terrain, 720820 m in elevation. A
gradient of open savanna types (68.1%) and dense
savanna (cerrado sensu stricto) (25.1%) can be found in
the park, as well as wet fields (4.9%) and riparian and
mesophyllous forests (1.2%) (Figure 3).
Up to 1984, the park was exploited by farmers for
cattle ranching and fire was used to promote forage
regrowth. After that time, the park was totally fenced,
and cattle were no longer permitted inside it. Since
then, a policy of fire exclusion was established in the
park, except for the annual burning of 314 km of
preventive firebreaks (I.B.D.F. 1981, IBAMA 1993). In
spite of this, uncontrollable wildfires occur every 3–4
years (Franc¸a and Setzer 1997).
The federal government owns all the parkland, and
there are no residents inside it. Visitors to the park are
always accompanied by an authorized guide.
Methods
Fire occurrences in Emas National Park were re-
corded in the field from June 1995 to May 1999
through direct observation. Additionally, the park was
checked for evidence of spot fires, by airplane, on three
occasions during the study period. We recorded for
each fire, the time it started and stopped and local
weather conditions during the burn. After each fire, the
burned area was immediately visited in order to locate
its perimeter, with the aid of a GPS (global positioning
system). The location of the initial fire point was esti-
mated by analyzing the remaining grass stalks, ash pat-
terns, and wind behavior, as suggested by Cheney and
Sullivan (1997).
Local rainfall was registered during the study period
by 35 rain gauges installed in the park, and additional
climatic data were obtained from the nearest climatic
station, in Mosteiro Sa˜o Jose´, Mineiros Municipality,
GO (Franc¸a and Setzer 1997). The climatic data were
used to build a climatic diagram according to Walter
and Lieth (Walter 1971) (Figure 2a) and a water bal-
ance diagram, according to Thornthwaite and Mather
(1955) (Figure 2b).
Using GIS software (IDRISI for Windows, version
2.0, Clark University), each fire occurrence was
mapped and the perimeter and extent of each burned
area was calculated.
A grid of 4 4 km was overlaid on the park map and
the randomness of the distribution of fire starts in each
cell was statistically tested by a chi-square test (Kershaw
and Looney 1964).
Fires were classified as natural or human-induced.
When the lightning strike that caused a fire had not
been observed in the field, the fire would be considered
natural if thunderstorms occurred at the time of fire
event, the fire focus was distant from park limits, and
visitors had not been in the park the day of the fire
event. If one or more of these conditions were not
satisfied, the fire would be considered human-induced.
We considered each natural fire as resulting from one
lightning strike.
Results
Fire outbreaks during the study period are pre-
sented in Table 1. Forty-five fires were registered and
five of them were considered human-induced. Forty-
one fires were identified immediately after they started
and four small burned areas were detected by airplane.
Three of the anthropogenic fires were caused by the
park staff when burning firebreaks, and the other two
came from farms outside the park, as observed in the
field. Four human-induced fires occurred during the
dry season, when vegetation was undergoing a water
deficit (Figure 2b), and burned a total of 7,942 ha; the
other one occurred in January and burned 866 ha. Ten
Figure 1. Cerrado region (according to I.B.G.E. 1992) and
the location of Emas National Park, Brazil.
LIghtning Fires in a Brazilian Savanna Park 677
fires happened in the seasonally transitional months
(May and September), burning 33,386 ha; 31 fires oc-
curred in the wet months, 30 of which were caused by
lightning (29,326 ha burned) and one of which came
from outside the park (866 ha burned). Multiple fire
points caused by a single lightning strike were not
observed, as in this case the fire points would appear
near each other and all fires registered were isolated.
Small spot fires merging to a large fire were not ob-
served.
The majority of wet-season lightning fires (76%)
were patchy, burned small areas (less than 500 ha)
Figure 2. Climatic diagram (a), following
Walter and Lieth (Walter 1971), and the re-
gional water balance (b), according to Thorn-
thwaite and Mather (1955), for Emas National
Park region. Data from the nearest climatic
station, in Mosteiro Sa˜o Jose´, Mineiros munici-
pality, Goia´s state (Franc¸a and Setzer 1997)
and from this study, for the period of 1985 to
1997. In a: black excess water, vertical
strips regular water supply, dotted water
deficit. In b: vertical strips surplus soil water,
right dashed soil water withdrawal, left
dashed soil water replenishment, dotted
water deficit).
678 M. B. Ramos-Neto and V. R. Pivello
(Figure 4) and were extinguished primarily by rain
(Table 2); active fire suppression was applied in only
two of them, and even so the main causes for their
extinction were rain, a natural barrier such as river or
gallery forest, or a burned firebreak. In contrast, dry-
season (June–August) fires burned larger areas com-
pared to wet season lightning fires, spread more
quickly, and required vigorous suppression efforts to
bring them under control (Tables 1 and 2). February
was the month with the highest fire incidence (11 fire
outbreaks with 1,312 ha burned), followed by Septem-
ber (eight outbreaks with 24,020 ha burned) (Figure
5).
During the study period, 53.4% of the park area did
not burn; 38.1% burned once; 8.4% burned twice, and
only 0.1% of the park burned three times (Figure 6).
Examination of the spatial distribution of fires revealed
some places in the park where fire outbreaks were more
frequent, and this was confirmed statistically when an-
alyzed against cells in a grid (
2
37.7; df 2; P
0.001). All lightning fires started on the flat plateau,
which occupies the highest elevation in the park and is
covered mostly by open vegetation (wet field or grassy
savanna) (Figures 3 and 6).
Discussion
Although scientists have long recognized lightning
as an important cause of wildland fires (Warming 1908,
Komarek 1972, Coutinho 1980, 1990, Tutin and others
Figure 3. Vegetation forms in Emas Na-
tional Park, Brazil.
LIghtning Fires in a Brazilian Savanna Park 679
1996, Middleton and others 1997), records of fire out-
breaks that included precise information on location,
area burned, and ignition source were not previously
available for the cerrados. In most cerrado parks and
reserves, human-caused fires are, indeed, much more
frequent than natural fires and originate at nearby
farms or urban areas (Pivello and Coutinho 1992).
The low incidence of anthropogenic fires in the
study area may be explained by several reasons. First,
preventive firebreaks, especially the ones located at the
park limits, had been maintained in reasonably good
condition by annual burning during the dry season,
thus avoiding the spread of fires coming from outside
the park. Second, mechanical agriculture now prevails
around the park, where fire is not frequently used.
Third, the fire-combat staff, although numbering only a
few persons and limited equipment, was present in the
park during the entire dry season and ensured a rapid
response when fires began. Finally, visitors in the park
were always guided by an authorized person and an
educational program was developed for farmers who
live near the park. However, these measures were not
able to suppress fire from the park because when hu-
man-induced fires are repressed natural lightning fires
predominate. That was evidenced by the highest fire
incidence during the wet months, probably related to
the number of lightning strikes in that period, since
heavy showers with thunderstorms and lightning are
frequent in the wet season.
Very few lightning strikes have been documented in
the cerrado region; the best available records come
from Pinto and others (1996), who registered 0.4 oc-
currences/km
2
in a place (Uberlaˆndia, MG, Brazil) that
lies at the same latitude as the Emas Park, about 400 km
east. Considering that in the present study each natural
fire was started by only one lightning strike and taking
the lightning records of Pinto and others (1996), we
Table 1. Fire outbreaks registered from June 1995 to May 1999 in Emas National Park, Brazil
Date
Natural fire Human-induced fire Total
area (ha)Number Area (ha) Number Area (ha)
Jun 95 2 6,780 6,780
Aug 96 1 792 792
Sep 96 4 4,628 4,628
Oct 96 1 9,619 9,619
Dec 96 2 6,767 6,767
Feb 97 4 275 275
Mar 97 2 23 23
May 97 1 61 61
Jun 97 1 370 370
Sep 97 4 19,390 19,390
Oct 97 1 1 1
Nov 97 1 70 60
Jan 98 2 323 323
Feb 98 2 377 377
Mar 98 1 378 378
Nov 98 1 1,592 1,592
Dec 98 3 2,716 2,716
Jan 99 4 4,164 1 866 5,030
Feb 99 5 659 659
Mar 99 1 2,362 2,362
May 99 1 9,307 9,307
Total 40 62,702 5 8,808 71,510
Figure 4. Fire outbreaks according to size classes (hectares)
and fire season, in Emas National Park, Brazil.
680 M. B. Ramos-Neto and V. R. Pivello
estimate that 1%–2% of the lightning strikes cause
wildfires in Emas National Park, not a negligible figure.
Although the highest fire incidence happened in
February (wet season), the total area burned (1,312 ha)
was relatively small, in contrast to September (transi-
tional month), when the largest cumulative area
burned (24,020 ha). Large fires in September were
probably related to weather and fuel conditions. By this
time of the year, the vegetation is cured and undergo-
ing severe water deficit (Figure 2b), the fuel is dry and
plentiful, especially if frosts occur (Pivello 1992, Pivello
and Norton 1996) and where the grass Tristachya leiosta-
chya is dominant (Ramos-Neto and Machado 1996).
The onset of the wet season in September brings heavy
Table 2. Main causes of fire extinction according to fire season in Emas National Park, Brazil
Causes of fire extinction Dry season Transition Wet season Area (ha)
Natural causes (rain, natural barriers or low
temperature) 0 4 14 5.459
Natural causes preventive firebreak 0 2 15 12.367
Natural causes suppression 0 2 0 8.383
Natural causes preventive firebreak
suppression 0 1 1 25.686
Preventive firebreak 0 1 0 10.807
Suppression 0 0 0 0
Preventive firebreak suppression 4 0 1 8.808
Total 4 10 31 71.510
Figure 5. Total fire outbreaks (a) and the total area (hect-
ares) burned per month (b), in Emas National Park, Brazil,
from June 1995 to May 1999.
Figure 6. Fire frequency in Emas National Park, Brazil, from
June 1995 to April 1999.
LIghtning Fires in a Brazilian Savanna Park 681
showers with thunderstorms and lightning, causing fire
outbreaks and spread (Schule 1990, Pivello 1992, Piv-
ello and Norton 1996).
Another factor that seems to influence fire occur-
rence is the elevation. Higher lightning fire occurrence
was registered in elevated plateaus. Frequent lightning
fires at high elevations have also been reported in Costa
Rica dry forests (Middleton and others 1997). The
altitude probably influences local meteorological con-
ditions and cloud formation, resulting in greater light-
ning incidence. This phenomenon, however, deserves
more investigation.
The present study shows the importance of natural
fires, at least in the most important protected cerrado,
Emas National Park. Cool fires in the wet season and
more intense fires in the transitional months may dom-
inate the natural pattern in the region studied, instead
of high-intensity winter fires, as has been believed up to
the present time. Wet-season fires usually burn small
areas due to the high moisture content in the vegeta-
tion (Pivello 1992) and are rapidly extinguished by the
heavy summer rains. Wet-season fires contribute to the
creation of a mosaic of low-fuel patches, which may
function as natural firebreaks and reduce the spread of
subsequent fires. This patchy landscape also provides
shelter for animals during a fire and maintains seed
banks of less fire-tolerant plant species; patchy burns
may increase the area of ecotones, permitting higher
diversity. In contrast, winter fires are hot, spread much
quicker, and may burn huge areas if fuel is abundant, as
often occurs under full fire-suppression policies.
As virtually no records of wet-season fires in cerrados
exist, studies and experimentation considering fire ef-
fects in flora and fauna until now have only considered
dry-season fires. In the case of Emas National Park, that
condition would be unrealistic, as most fires occur be-
tween September and May. In that case, the response of
plants and animals to fire may be different than those
described in the literature. For instance, studies on
plant biomass production after fire indicate very differ-
ent results according to whether the burn occurs in
June, September, or November (Ramos-Neto, personal
communication).
Conclusion: Are Present Fire Management
Strategies Adequate?
The lack of more precise information on cerrado
fires and the fact that policy-makers are not well in-
formed on recent advances in fire ecology have led to
inadequate management policies concerning fire in
cerrado preserves (Pivello 1992). Full-suppression pol-
icies come from conservative attitudes and are based on
past ideas about the harmful effects of wildland fires.
This is reflected in the fact that legislation permitting
the use of management burning, in special cases, was
not passed until 1988/89 (IBDF Law No. 231-P/88;
CONAMA Resolution No. 011 from 14 December 1988;
Federal Decree No. 97635 from 10 April 1989).
The policy of total fire suppression has proved to be
inadequate in cerrado preserves, as extensive and hot
fires periodically occur when fuels accumulate, de-
manding huge efforts and cost to be controlled. A
proper management policy in protected cerrados
should be based on continuous monitoring and assess-
ment of flora and fauna responses to specific fire re-
gimes. It should include the possibility of using natural
or periodic hazard-reduction fires in view of all the
benefits fire can bring to the ecosystem.
In the case of Emas National Park, we suggest that
natural lightning fires should be allowed to burn and
should be monitored; fire suppression should occur
only if the fire becomes too large or intense. Fuels
should also be monitored and a patch-burning strategy
using prescribed fires could be adopted for hazard
reduction. The effectiveness of this strategy has been
demonstrated in savanna parks elsewhere in the world
(Edwards 1984, Bradstock and Bedward 1997, Gill
1997).
Preventive firebreaks must be maintained, especially
at the park limits, because they are reasonably effective
in containing the spread of winter fires. However, the
number of firebreaks and their location and width
should be reviewed, especially if a patch-burning strat-
egy is adopted. At present, firebreaks are kept clean of
fuel by burning strips 25–60 m wide, by the middle of
the dry season. We recommend they be burned early in
May, both to follow a more natural burning pattern
(since lightning fires still occur in May) and because
burning is safer when vegetation is not so dry. Guide-
lines for prescribed fires in cerrados are discussed in
more detail by Pivello (1992) and Pivello and Norton
(1996).
In conclusion, a fire management policy that inte-
grates natural and prescribed fires with conservation
goals should be adopted in cerrado preserves. The
present policy concerning wildland fire in Emas Na-
tional Park may not protect its biodiversity on the long
term because of the damage to native flora and fauna
resulting from uncontrollable winter fires. A flexible
strategy of allowing and monitoring wet-season fires
and patch-burning when necessary would be a more
appropriate approach to maintaining the park natural
species and habitat diversity. This strategy has to be
based on additional studies of cerrado dynamics and
fire ecology and on continuous monitoring. Further-
682 M. B. Ramos-Neto and V. R. Pivello
more, fire management actions must account for local
conditions, since fire behavior is dependent on climatic
events that may differ from one region to another.
These differences will affect the basic approach to fire
management, including how firebreaks are designed,
the scheduling of prescribed fires, the circumstances
under which fires are allowed to burn, and postfire
dynamics in the communities.
Acknowledgments
The authors wish to thank the Emas National Park
staff for their assistance in the field, especially Ary
Soares dos Santos and Jose´ Carlos Bernardo, and WWF-
World Wide Fund for Nature, Brazil, for financial sup-
port.
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684 M. B. Ramos-Neto and V. R. Pivello
... No parque, as fisionomias abertas de cerrado predominam (68,1% de sua área), mas formações mais fechadas também ocorrem (25,1%). Outros tipos vegetacionais também aparecem no parque, como campos úmidos (4,9%) e florestas ripárias e semidecíduas (1,2%, Ramos-Neto & Pivello 2000). Em geral, os solos são pobres em nutrientes, bem drenados e ácidos (Silva & Batalha 2008). ...
... Até 1984, o Parque Nacional das Emas era queimado anualmente na estação seca para promover a renovação de pastagens naturais (França et al. 2007). A partir desse ano, o parque foi cercado, o gado retirado e uma política de exclusão do fogo foi estabelecida (Ramos-Neto & Pivello 2000). Como consequência, com o acúmulo de biomassa seca, queimadas catastróficas passaram a ocorrer a cada 3-4 anos, atingindo aproximadamente 80% da área do parque (Ramos-Neto & Pivello 2000). ...
... A partir desse ano, o parque foi cercado, o gado retirado e uma política de exclusão do fogo foi estabelecida (Ramos-Neto & Pivello 2000). Como consequência, com o acúmulo de biomassa seca, queimadas catastróficas passaram a ocorrer a cada 3-4 anos, atingindo aproximadamente 80% da área do parque (Ramos-Neto & Pivello 2000). Desde 1994, cerca de 10 km² de aceiros preventivos têm sido queimados anualmente no final da estação úmida, e uma brigada de combate ao fogo trabalha no parque durante a estação seca para impedir que queimadas antrópicas se espalhem. ...
Article
O fogo é um importante agente evolutivo que pode causar alterações florísticas, filogenéticas e funcionais nas comunidades vegetais de cerrado, alterando a composição do solo e modificando as interações interespecíficas. Aqui discutimos os efeitos do fogo sobre a vegetação de cerrado e levantamos sugestões para o seu manejo em unidades de conservação. Com especial ênfase para trabalhos realizados no Parque Nacional das Emas, na fisionomia de campo cerrado, compilamos os seguintes resultados: em maiores frequências de fogo (queimadas anuais ou bienais) ocorre agrupamento fenotípico, diminuição da competição, diminuição da biomassa vegetal e enriquecimento dos solos; em menor frequência (sem queimadas há doze anos), há maior competição entre as espécies e grande acúmulo de biomassa seca. Além disso, diferentes regimes de fogo suportam diferentes composições florísticas, com grupos de espécies exclusivos em cada regime, tanto de espécies herbáceo-subarbustivas quanto de arbustivo-arbóreas. Portanto, sugerimos que seja mantido um mosaico com diferentes regimes de fogo e que se evitem áreas de cerrado sem queimadas por muitos anos. Palavras-chave: biomassa vegetal, diversidade filogenética, diversidade funcional, manejo, solo.
... Ainda que o fogo seja reconhecido como um dos fatores determinantes à estrutura, biodiversidade e funcionalidade do Cerrado (MYERS, 1936;FURLEY, 1999), a adaptação da sua vegetação se deu, evolutivamente, em um regime onde o fogo ocorria no início da estação chuvosa, resultado da incidência de raios PIVELLO, 2000), momento que difere da maior parte das cicatrizes identificadas no PETeR, as quais correspondem ao período de seca, reforçando ser fruto das ação antropogênicas aqui apresentadas. ...
... Apesar de não haver um consenso em relação à frequência ideal de queima na vegetação, sabe-se, entretanto, que a alta frequência de incêndios pode provocar danos variados à vegetação arbórea do Cerrado (SATO, 2003), com espécies mais sensíveis ao fogo não conseguindo manter uma taxa positiva de crescimento populacional (HENRIQUES, 2005). Outro entendimento, e que é consistente com a história evolutiva do Cerrado, é que a estratégia de supressão total do uso do fogo, como identificado nas áreas em que não houve queima durante o período avaliado, é considerada uma abordagem inadequada à conservação do Cerrado PIVELLO, 2000), podendo, a exclusão total do fogo, levar à mudança na estrutura e composição da vegetação (BOND; MIDLEY, 1995;KEELEY et al., 2011;DANTAS;BATALHA;PAUSAS, 2013). ...
Article
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Embora congregue a maior parte das áreas queimadas no Brasil, o Cerrado ainda carece de informações detalhadas acerca do regime do fogo em algumas localidades do seu território. Visando contribuir ao atendimento desta demanda, o presente trabalho objetivou caracterizar, para o período de 1984 e 2020, o regime de queima no Parque Estadual de Terra Ronca (PETeR), localizado no estado de Goiás. A partir da interpretação de imagens do satélite Landsat, foram identificadas cicatrizes de incêndio em todos os anos analisados, não sendo observado incêndio de grande porte ou relação clara com o histórico de criação, de demarcação ou fundiário do Parque. Em relação à frequência, duas regiões foram discriminadas, apresentando, ambas, baixa recorrência de queima. O regime identificado no PETeR sugere a manutenção da vegetação no Parque e, deste modo, o cumprimento do objetivo básico desta categoria de UC.
... Natural wildfires have been occurring, at least, during the last four million years in the Cerrado, and fire has been a natural selection factor that has led to most of the flora being fire-resistant due to morphological and physiological adaptations (NASCIMENTO, 2001). It is also important to emphasize that natural fires occur between three and six years, and that human-induced wildfires have different characteristics and have negative impacts on the Cerrado (RAMOS-NETO; PIVELLO, 2000;JÚNIOR et al., 2014). When analyzing the fire-foci of 2022 by states containing Cerrado vegetation, we observe that, except for Mato Grosso (MT), the four states with the highest number of hotspots identified by the INPE reference satellite (INPE, 2023b) are located in the MATOPIBA region. ...
Thesis
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The Brazilian Cerrado, a hotspot for global biodiversity conservation, evolved under the presence of natural wildfires. Fire has become frequent and widespread, and the Cerrado, where natural fires have occurred for at least four million years, is threatened by human-induced wildfires. The Chapada dos Veadeiros National Park (CVNP), located in the state of Goiás, Brazil, was established in 1961 and currently covers 240,611 ha. In 2017, approximately 66,000 ha were burned in the CVNP, and the Integrated Fire Management (IFM) was implemented still in that year to reduce the negative impacts of future criminal/accidental events. Remote Sensing (RS) data show that there were fire-foci in the CVNP during the dry months of 2020, 2021, and 2022. There are two RS-based products for wildfires detection: products of released heat and products of biophysical changes in vegetation. As an example of provider, there is the Queimadas Program of Brazil’s National Institute for Space Research (INPE), which provides products on daily fire hotspots and a monthly product of burned areas for the Cerrado. As of the current date, there are no products that employ Brazilian satellite images for the systematic mapping of burned areas. The objective of this research is to explore methods for supervised classification of time series images captured by the Wide Field Imager (WFI) sensor on board the CBERS-4, CBERS-4A, and AMAZONIA-1 satellites, using the Random Forest (RF) algorithm. The study area is the CVNP and its buffer zone of 10 km, and the time window covers the years 2020, 2021 and 2022. A total of 382 images were acquired from INPE archive and after filtering for cloud cover it was decided to keep 235 images: 50 from 2020, 72 from 2021 and 113 from 2022. The WFI sensor has four spectral bands (BGR NIR), which is a limiting factor. Consequently, we estimated and integrated the BAI (Burned Area Index), EVI (Enhanced Vegetation Index), GEMI (Global Environmental Monitoring Index), NDVI (Normalized Difference Vegetation Index), and NDWI (Normalized Difference Water Index) spectral indices into a regular grid with 500 m x 500 m cells, totalling 38,957 cells. For each one of the previous spectral indices more the NIR band, datasets containing anual and semi-annual observations were structured and the models were trained using samples of “burned areas” and “unburned areas” previously collected through visual image analysis. The annual models achieved at least 90% accuracy and the best generalization results were observed using multi-temporal datasets. The results of this research indicate that, given a representative sample set, it is possible to detect burned areas in the CVNP using WFI imagery.
... Annually, millions of acres have been burnt due to wildfires making it a national scale problem in many countries (Busenberg, 2004). Natural wildfires take place mainly due to lightning, volcanic eruptions and dry climate and vegetation (Ramos-Neto & Pivello, 2000). However, it is also recorded that 90% or more of the wildfires are caused mostly due to human behaviour, such as disposal of cigarettes in the open air, camping fires and garbage burning (Reisen et al., 2015). ...
Thesis
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Predicting wildfires using Machine Learning (ML) models is relevant and essential to minimize wildfire threats to protect human lives and reduce significant property damages. Mixed results have been found in this domain, potentially because of dataset manipulations to enable multi-class classification. This is because two or more classes are used in wildfire prediction modelling, where non-fire labels are created artificially, leading to an unbiased dataset for non-fire data. This thesis aims to discuss research that built wildfire prediction models using One-class classification algorithms. The significant features that influence wildfire ignition were derived from One-class ML models using the Shapley values method which is a novel contribution to the wildfire prediction domain. Elevation, vapour pressure deficit and dew point temperature were among the most influential features that were derived using the Shapley values method. The One-class algorithms used were Support Vector Machine, Isolation Forest, Neural network-based Autoencoder and the Variational Autoencoder models. The input features to the models were grouped based on topography, weather, plant fuel moisture, and population. Outcomes were validated using 5-fold cross-validation to avoid bias in the training and testing dataset selection on the ML models’ performances. These One-class models resulted in a high mean accuracy ranging from 98-99%, exceeding multi-class models’ performances in similar environmental conditions. The findings of the research have the potential to influence the state-of-the-art methods in wildfire prediction. Finally, a web-based tool to predict wildfires is presented as a proof of concept to show the usability of ML models for wildfire predictions.
... Natural fires in the open physiognomies of Cerrado are initiated by lighting during the dry-wet season transition, usually followed by rain, or in the short dry spells at the onset of the rainy season (5 to 10 days), with a frequency of 1 to 9 years [70]. While burned areas in the dry-wet season transition can reach >10000 ha, during the short dry spells in the rainy season the burned area is smaller than 500 ha [70,71]. Nowadays fire regime has changed, and most Cerrado fires are anthropogenic, burning large areas in the dry season (May to September), with a frequency varying from 1 to 4 years [70,72]. ...
Article
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Several herbaceous species exhibit mass flowering after fires in Neotropical savannas. However, unequivocal evidence of fire dependency and the consequences for plant reproduction are lacking. In nutrient-poor fire-prone savannas, the damage caused by fire and by other means (e.g., leaf removal, but not necessarily having a negative impact) constrains the maintenance and expansion of plant population by affecting the ability of individuals to recover. Therefore, the compensatory responses of plants to both damages should be convergent in such environments. Using Bulbostylis paradoxa–reported to be fire-dependent to flower–as a model, we investigated the role of fire and leaf removal in anticipating the flowering and reproduction periods, and its possible consequences on seedling establishment. We monitored 70 burned individuals, 70 damaged/clipped, and 35 without damage to estimate time for flowering, seed quality and germination parameters. To expand our sampling coverage, we examined high-resolution images from herbarium collections in the SpeciesLink database. For each herbarium image, we recorded the presence or absence of a fire scar, the month of flowering, and the number of flowering stalks. Bulbostylis paradoxa was fire-stimulated but not dependent on fire to flower, with 65.7% of the individuals flowering in the burned area, 48.6% in the clipped, and 11.4% in the control. This was consistent with the analysis of the herbarium images in which 85.7% of the specimens with flowers had fire scars and 14.3% did not. Burned individuals synchronized flowering and produced more viable seeds. However, the seeds might face a period of unsuitable ecological conditions after early to mid-dry season fires. Flowering of unburned plants was synchronized with the onset of the rainy season. Flexibility in flowering and vegetative reproduction by fragmentation confer to this species, and most likely other plants from the herbaceous layer, the capability of site occupation and population persistence in burned and unburned savanna sites.
... Furthermore, the suppression of fire may not be ecologically sound (Ramos-Neto and Pivello 2000), as it ignores the local characteristics or the potential benefits that fire can provide, given that fire is a natural event or a part of the dynamics for many communities (Miranda et al. 2002;França et al. 2007). Fire is a fundamental factor for the maintenance of several areas of savannahs worldwide (Walter and Ribeiro 2010) and promotes environmental heterogeneity and, consequently, beta diversity, which is the diversity between sites in the savannah (Silva and Batalha 2008). ...
Article
Full-text available
The objective of the study was to analyze the occurrence of forest fires in a conservation unit (CU) of the Brazilian savannah using remote sensing techniques and statistical methods developed for spatial punctual processes. To conduct the spatial analysis of fires, fire polygons mapped using Landsat 8 satellite images were used. The fires were considered into size classes to better illustrate the spatial patterns. The analysis of the spatial distribution of fires utilized Ripley's K-function, in addition to the Kcross function to verify spatial interaction. The results show that the year 2015 had the highest number of fires and burned area. Smaller fires represent a greater number of occurrences, located mostly on CU boundaries. The spatial distribution of forest fires is not random and can cluster on a scale of approximately 6 km. There is a strong spatial interaction between forest fires and traditional communities, particularly with fires smaller than 100 hectares. However, these communities are not responsible for large fires. These results contribute to better-targeted forest fire prevention and combat policies, serving as management tools for the protected area. Graphical Abstract
... These types of fires are triggered at the height of the dry seasons and reach high intensities, devastating vast areas of vegetation. In contrast, natural fires, which are caused by electrical discharges, generally occur at the beginning of the rainy season [12]. ...
Article
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Although fire is a natural phenomenon in the dynamics of some biomes around the world, it can threaten the biodiversity of certain ecosystems. Climate change and the expansion of anthropogenic activities have drastically increased the occurrence of large-scale burnings worldwide. The 2020 fire events in the Pantanal marked a historically unprecedented record, burning an area of approximately 40,000 km2. However, how fires affect the local wildlife has yet to be evaluated. The aim of this study was to investigate the recovery of the avifauna in the Pantanal of Mato Grosso by comparing data selected from a previous study conducted between 2014 and 2016 with data collected in burned areas nine to twelve months after the fire. We compared diversity and community composition, investigated the influence of species trait foraging guild, foraging strata, and body mass on their response to fire, and complemented it with species’ individual responses. Bird richness and Shannon diversity were lower in burned areas, and the composition significantly varied between burned and unburned areas. The species’ response toward burned and unburned areas was significantly mediated by their traits, with smaller, piscivorous, omnivorous, ground and water, and midstory to canopy species being the most sensitive toward the environmental changes caused by the fire. Thirty-three species showed a negative response toward burned areas, but 46 species showed the opposite response, and 24 species were similarly abundant in unburned and burned areas. The present study is the first evaluation of the response of birds to the extreme fire events in the Pantanal and provides valuable insight into the recovery and resilience of local avifauna.
... In 2005, about 48% of wildfires in Canada's remote areas were caused by lightning strikes [21]. From 1995 to 1999, nearly 89% of lightning-induced fires occurred in the Emas National Park in Brazil [22] whereas from 2002 to 2003, lightning strikes caused 13 wildfires [23] in the same area. According to the National Interagency Fire Center, Boise, Idaho [24] statistics, from 2001 to 2020, the highest number of lightning-induced wildfires occurred in the southwest (Figure 1a). ...
Article
Full-text available
Wildfire causes environmental, economic, and human problems or losses. This study reviewed wildfires induced by lightning strikes. This review focuses on the investigations of lightning mechanisms in the laboratory. Also, the paper aims to discuss some of the modeling studies on lightning-induced wildfires at different geographical locations using satellite-recorded lightning data and different statistical analyses. This review established that irrespective of the different models used to predict lightning wildfires, there is still a lack of understanding of the lightning-strike ignition mechanism; few experiments have been modeled to establish the dynamics of lightning-strike ignition. Therefore, further research needs to be carried out in this area to understand lightning ignition. It was ascertained from the various statistical modeling that lightning-induced wildfires are exacerbated by the abundant availability of fuel with a lower moisture content and high lightning efficiency. Moreover, because of changes in the climate and weather conditions, i.e., harsh weather and climate conditions due to anthropogenic activities, lightning-induced ignition wildfires have increased over the years, and they are expected to increase in the future if the climate and weather conditions continue to aggravate. Although various modeling studies have identified that lightning-induced wildfires have increased recently, no preventive measures have been conclusively proposed to reduce lightning-caused wildfires. Hence, this aspect of research has to be given critical attention. This review presents information that gives a profound understanding of lightning-induced wildfires, especially factors that influence lightning wildfires, and the state-of-the-art research that has been completed to understand lightning-induced wildfires.
Article
Aim Changes in fire regimes and biological invasions are major threats to tropical savannas. Fire is a key driver of community composition in these ecosystems and can be used as a management tool to control some invasive alien species, while being advantageous to native ones. However, we still do not fully comprehend the interactive effects of these threats on native plant communities. Here, we conducted an experiment in southeastern Brazil to investigate how variation in the composition of native communities invaded either by Melinis minutiflora or Urochloa brizantha is affected by fire in different seasons: early‐dry season, mid‐dry season and late‐dry season in comparison to fire suppression. Location Itirapina, state of São Paulo, southeastern Brazil (22°14′07″S 47°53′07″W). Results The effects of fire seasons and invasive species were independent for species richness but interactive for species gains and losses. In general, the identity of the invasive species was a key factor driving community dynamics, with fire seasons playing a weaker role. Invaded communities changed gradually over time and the major changes happened over longer time lags. Communities invaded by M. minutiflora gained more species than those invaded by U. brizantha. Thus, communities invaded by M. minutiflora also had more variation in their species richness through time than those invaded by U. brizantha . Conclusions Although biological invasions and fire seasons interacted as drivers of change in native savanna communities, the identity of the invasive species played a stronger role. Communities invaded by M. minutiflora gained more species and were more variable than those invaded by U. brizantha .
Book
Grassfires: Fuel, Weather and Fire Behaviour presents information from CSIRO on the behaviour and spread of fires in grasslands. This second edition follows over 10 years of research aimed at improving the understanding of the fundamental processes involved in the behaviour of grassfires. The book covers all aspects of fire behaviour and spread in the major types of grasses in Australia. It examines the factors that affect fire behaviour in continuous grassy fuels; fire in spinifex fuels; the effect of weather and topography on fire spread; wildfire suppression strategies; and how to reconstruct grassfire spread after the fact. The three meters designed by CSIRO for the prediction of fire danger and rate of spread of grassfires are explained and their use and limitations discussed. This new edition expands the discussion of historical fires including Aboriginal burning practices, the chemistry of combustion, and the structure of turbulent diffusion flames. It also examines fire safety, including the difficulty of predicting wind strength and direction and the impact of threshold wind speed on safe fire suppression. Myths and fallacies about fire behaviour are explained in relation to their impact on personal safety and survival. Grassfires will be a valuable reference for rural fire brigade members, landholders, fire authorities, researchers and those studying landscape and ecological processes.
Chapter
In this chapter an attempt is made to summarize our understanding of the changes caused by fire in vegetation of different South African biomes. Concepts of succession are reviewed as a background to what follows. Then the responses in vegetation structure that have been documented in the region are summarized, as well as published information on the different vegetation structural variables that have been shown to respond to fire. Finally, information on fire effects is summarized for fynbos, forest, grassland and savanna. Information on the karoo biome is too scant to justify a review.
Article
Fire is a major determinant of cerrado (savanna) vegetation in Brazil, and is used as a management tool during the dry season. This has consequently induced a long history of fire studies in the region. This article reviews past and present fire ecology studies in the cerrado, and emphasizes the need for a more applied approach to future work.
Chapter
Fire is widely accepted as being a valuable tool in the management of natural vegetation. It is a resource modifier (Cutler 1979) and can be used to change the composition of vegetation and its cover or to maintain plant communities in a certain stage of succession. So too in South Africa, where fire has, it would seem, played a role in determining the nature of vegetation for many hundreds of years (chapters 3 and 4). Not unexpectedly, therefore, it has continued to be used by farmers and others in the management of this vegetation. Here its use must be dictated by the desired objectives, the known reaction of the plant communities to burning, the management systems into which it is to be incorporated and by the local legislation pertaining to the use of fire. Previous chapters have dealt with the reaction of plant communities to fire and this chapter will deal with three specific aspects viz the objectives of burning, the incorporation of fire into some management systems and fire legislation.
Chapter
Landscapes are more than a simple function of geological, geomorphological, climatic, and botanical parameters. Animals play an important role. Their behavior, especially their trophic habits, is a major force in the forming of landscapes. Herbivores consume the products of the primary biomass production. Fire and man have been doing the same since they appeared on Earth. Moreover, both are not only herbivorous, but also carnivorous, devouring whatever animal wherever they can.