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Biogeographic Patterns in Food Web Organization. Oak Ridge Natl. Lab. Spec. Rept.

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Frederic Briand at Mediterranean Science Commission, Paris, Monaco
Frederic Briand
  • Mediterranean Science Commission, Paris, Monaco
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UNION
CARBIDE
OANL-SN3
•
•
Cu
Trends
In
Web
Theory
Report
on
a
Food
orkahop
October
25--27,
1882
Fontana
Inn,
C.roln
•
•
-
•
•
Under Contract W-74oa-eng-26
CURRENT
TRENDS
IN
FOOD
WEB
THEORY
REPORT
ON
A
FOOD
WEB
WORKSHOP
October
25-27.
1982
Font-1na Village Inn, North Carolina
Organized
and
Edited by
D.
L. DeAngelis
W. M. Post
G. Sugihara
'.
HOST
:
OAK
RIDGE
NATIONAL
LABORATORY
SPONSOR
:
NATIONAL
SCIENCE
FO
U
NDATION
Date
publi
s
hed
: October
1988
OAK
RIDGE
ATIONAL
LABORATORY
OAK
RIDGE,
TENNESSEE
37880
OPERATED
BY
UNION
CARBIDE
CORPORATION
FOR
THE
U.S
.
DEPARTMENT
OF
ENERGY
ORN
L-
fi98.'l
l
,:r
~
('tur
r
ent
Trends
in
F
ood
Web
Theory.
1983.
"
ORNL
-
5983.
O~~
Ridge
National
Laboratory,
37
DeAng
elis
,
D.L.,
Tennessee.
W.M.
Post
and
G.
Sugihara,
eds
Biogeographic
Patterns
in
Food
Web
Organization
Frederic
Bri
and
Due to
th
e low
number
of r
ea
l food webs generally known from
th
e published record.
we
have
been so far unable to
appreciate
th
e
pa
rt,
if
there
is any, played
by
the
abiotic environ-
ment in s
ha
ping trophic s
tructur
e,
To tackle
the
problem, I
first
assembled a collection of
40
real
community
webs. On
that
, ,
basis I
established
that
trophic
structure
is markedly affected by
the
degree of variability,
independe
nt
of predictability,
of
the
physical environment.
Thus
food webs in
fluctuating
syst
ems
are
characterized
by a significantly lower connectance
than
webs
reprcsentative
of
more
consta
nt
environments
(Briand
19
83)
. .
The
same
collection also revealed some
str
iking
rela
tions between
habitat
type
and
food
web
orga
nizat
ion. In
particular
forest, pelagic
an
d
inter
tidal
communities
cmerged
as
dis-
tin
ct
groups
in
the
s
pa
ce
defined by connectance, species richness
and
herbivorous fraction.
This, however, could only be described as a quali
tat
i
ve
trend since
the
numb
er of webs
representing
each biome
was
too small to allow
statistical
analysis
(Briand
19
83).
To p
ursue
the
question
fur
the
r I extended my collection
of
c
ommun
it
y webs to
62.
These
are
repr
esen
tative
of a wide
variety
of environmen
ts
from all
lati
tudes
(see Table 1). The
statistics
of
the
main food web
parameters,
given in Table
2,
indica
te
a
lar
ge degree
of
var-
iance for
most
indices. As
an
as
ide,
it
appear
s
worth
noting
that
as
many
as
51
webs (i.e.,
82% of
the
collection)
are
"interval
graphs,"
which provides additional
support
to
the
find-
ings of Cohen (1978).
A principal component analysis of all food web variables reveals
that
three
factors
acco
unt
for more
than
76%
of
the
var
iance in
the
data.
The
product
SC (species
richne
ss
x upper connec
ta
nce), ranging from 2.3 to 20.8,
is
by
far
th
e
maj
or c
ont
ributor
to
the
fir
st
factor. Average chain length and fraction of
strict
herbivor
es-the
latt
er indica-
ti
ve
of food
web
'wid
th'-contrib
ut
e
th
e most to
the
second factor,
but
in exactly opposite
ways. In
other
words
the
widest f90d ,webs will
tend
to be
th
e
shortest,
and
vice versa.
Lastly,
fr
act
ion of top carnivores weighs
the
most on
the
third
factor.
Int
e
restingly
,
neith
er
fr
action
of
om
ni
vores Ithose or
ga
nisms feeding on more
than
one
trophic
level)
nor
fraction
of specialists
appear
among
the
major disc
riminating
variables.
Table
1.
Biogeogra
phic
classification
of
62
food
webs
Environmental
variability
fluctuating 43
constant
19
Latitude
tropical
t
e
mp
e
r
at
~
,
high l
at
itude
Environment
totally
aquatic
tota
ll
y te
rr
es
trial
in
terface
14
38
10
32
9
21
38
Table
2.
Basic
statistics
for
62
food
webs
Variable
no.
of
organisms
lower connectance
connectance
0
CUfFe)
trophic
links
•
potential
competitive links
average
chain
le
ngth
max.
chain
length
%
herbivores
% top
carnivores
%
int
erm.
consumers
% omnivores
% specialist
consumers
Mean
17
.85
0.
26
0.43
33
.
29
38
.
39
2.86
5.19
32
.
68
22.44 '
54.05
27.44
41.10
Range
5-45
0
.05
-0.60
0.1
8-0.85
6-95
1-257
1.85-5.92
3-9
5-55
6-42
20-79
0
-64
0-88
°Note:
upper
connectance
takes
potential
competition
int
o account; lower connectance does
not
(see
Briand
19
83
for
detail
s).
Next, predefined
groups
of food webs
corresponding
to dis
tinct
habitat
types
and
envi-
ronm
e
ntal
regimes
were compared, using
discriminant
analysis.
This
revealed profound
and
significant
di
stinctions
in
trophic
s
tru
ctu
re, no
tab
ly between ' '
1.
fluctuating
(low sc)
and
constant
(high sc)
systems
(p < 0.0001).
This
confirms
a
the-
,
oretical
speculation of May (1981)
and
sug
gests
that
feeding
optimization
impo
se
s
struc-
tural
changes
when
the
level of
environmental
perturbation
is relatively high (see Bri-
and
1983).
2.
pelagic (longer food chains)
and
sub
litt
o
ral
benth
ic
(shorter)
syste
ms
(p = 0.004).
This
may
be due to a lower
assimilation
efficiency in benthic
syste
ms,
where
the
energy
transfer
is largely
detritus-based.
3. two-dimensional (sh
orte
r, wider) and
th
ree-dimensional (longer,
thinner
)
systems
(p
= 0.009).
4.
pelagic
three-dim
ensi
onal
aquatic
(more
generalists)
and
three-dimen
siona
l
terrestrial
(more
specialists)
systems
(p = 0.015).
5.
intertidal
and
sublittoral
(high sc)
syste
ms (po = 0.015).
Fo
r
reasons
outlined in
(l)
above.
Clearly then, habi
tat
type, geometrical
co
nfigurati
on
and
temporal
variability
of
the
em
'ir
onment,
are
l
ea
ding
factors
as
far
as food web s
tructure
is
cO
,neerned. In conclusion
(sec
Fil!. 1 I. I propose
as
a
wo
rking hypothesis
th
at
there
exist four
different
sets
of
com-
munity
assembly rules
corre
sponding to four
major
biomes
(interti
da
l,
sublittoral.
pelagic
and
3-D
terr
estr
ial i.e
.,
forestsl, to which we may soon add a fifth (2-D
terrestrial
i.e.,
tundra.
I!l·assland. dese
rt)
once re
pr
ese
nt
at
i
ve
webs become available.
Acknowledgment
s
!
am
I!rateful to
Peter
Yodzis who kindly provided me wi
th
some of
the
co
mp
ut
er pro-
.E:!Tam~.
•
39
ORNL-OWG
83·1695
WIDTH
---~
/'
......
I
",
//--
~'-
f
/,'
\
"GRASSLAND
/ \
" ? I
\
INTERTIDAL
\ { SUBMERGED !
\
BENTHIC
/
" J \ /
, - "r
.-\-
./
........
/'
"
---
.....
____________
~~~f-~:
.....
------~~~~·~-~----~SC
( FORESTS I
\ J '
\
__
--I.
-._
/ /
.---
.......
----L
./
.......
/
'"
f \
\ PELAGIC \
\ I
, /
" /
.......
/'
-------'"'
~
LENGTH
Fig
.
1.
Schematic
segregation
of
major
biomes
based
on
three
food
web
characteris-
tics:
sc,
food
weh
width,
and
average
food
chain
length.
REFERENCES
Briand. F.
1983.
Environmental control of food web structure. Ecology
64:
253·263.
Cohen, J. E.
1978.
Food Webs and Niche Space. Princeton University Press. Princeton, New
Jersey.
189
pp. ,
May,
R.
M.
1981.
Patterns
in
multi·
species communities. IN:
R.
M.
May (ed.). pp. 197·227.
The(JT"etical
Ecology.
W.
B. Saunders, Philadelphia.
... We know from comparative studies of real food webs (COHEN 1978;PIMM 1982;BRIAND 1983 a) that these seemingly complex, tangled, networks are actually highly patterned. How much of this is due to energetic constraints (YODZIS1983), stability (PIMM1982) or environmental constraints (BRIAND1983 a, b) remains to be seen. ...
... The discrimination between both groups is highly significant (simple discriminant analysis; P = 0.0011). The reader interested in the statistics of the parameters recorded for each group is referred to Table 3. Unless it is a monumental coincidence, the web segregation discovered here among lakes, streams and reservoirs strongly supports the claim that the physical nature of the environment is a major determinant of food web structure (BRIAND 1983 a). However, if the connection between ecosystem structure and trophic structure appears convincing, one can only speculate about its actual mode of operation. ...
View
View
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  • Jan 1984
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Habitat dimensionality and mean search distances of top predators: Implications for ecosystem structure
Article
  • Aug 1992
The foraging success of top predators may be influenced by the shapes of their habitats. We show here that when a two-dimensional habitat is restricted to a narrow strip or a three-dimensional system to a thin plate, then searching predators must travel further between prey items. This result holds when the width of the strip or thickness of the plate is narrower than twice the perception range of the predator, and when prey are not particularly abundant. If, as would be expected, travel time and energy expenditure increase with distance travelled, restricting the dimensionality of a habitat will decrease the net energy gain of a predator per prey consumed. This in turn may affect the size of a predator population that a given habitat can support, and ultimately determine whether the top predator species is viable in the habitat. This mechanism provides one explanation for observed relationships between the lengths of food chains and habitat dimensionality.
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Towards an Integrated Environmental Assessment for Wetland and Catchment Management
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  • Jun 2003
  • GEOGR J
This paper develops a decision support system for evaluation of wetland ecosystem management strategy and examines its, so far partial, application in a case study of an important complex coastal wetland known as the Norfolk and Suffolk Broads, in the east of England, UK. Most managed ecosystems are complex and often poorly understood hierarchically organized systems. Capturing the range of relevant impacts on natural and human systems under different management options will be a formidable challenge. Biodiversity has a hierarchical structure which ranges from the ecosystem and landscape level, through the community level and down to the population and genetic level. There is a need to develop methodologies for the practicable detection of ecosystem change, as well as the evaluation of different ecological functions. What is also required is a set of indicators (environmental, social and economic) which facilitate the detection of change in ecosystems suffering stress and shock and highlight possible drivers of the change process. A hierarchical classification of ecological indicators of sustainability would need to take into account existing interactions between different organization levels, from species to ecosystems. Effects of environmental stress are expressed in different ways at different levels of biological organization and effects at one level can be expected to impact other levels, often in unpredictable ways. The management strategy, evaluation methodologies and indicators adopted should also assess on sustainability grounds whether any given management option is supporting, or reducing, the diversity of functions which are providing stakeholders with the welfare benefits they require.
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Food Webs: What Can They Tell Us About the World?
Article
Full-text available
  • Jan 1996
This book unites diverse approaches from theoretical ecology and empirical research insystems ranging from soil fauna to oceans. Major philosophical and methodological differences are expected from such a heterogeneous group of ecologists; indeed, one might be amazed by the establishment of a substantial common basis for discussion. Food webs provide this basis. Much recent ecological literature is cast within a food-web framework, including studies of 1) Habitat heterogeneity and the regualtion of community structure(e.g Lubchenco 1983; Kareiva 1986; Moore & Hunt 1988; Moore 1989) 2) environmental change through time and community structure and function (Menge & Sutherland 1976; Winemiller 1990; Schoenly & Cohen 1991) 3) productivity gradients and community structure (Oksanen et.al. 1981; Persson et.al. 1988, 1991) 4) direct and indirect cascading effects of predation on community structure (Paine 1980; Power et.al. 1985; Carpenter et.al.1987; Kerfoot 1987; Yodzis 1988; Schoener 1989; Spiller & Schoener 1990; Turner & Mittelbach 1990 5) intraguild predation (Polis et.al.1989; Oksanen 1990; Polis & Holt 1992 6) indirect mutualism (Vandermeer et.al.1985) 7) apparent competition (Holt 1984; Holt & Kotler 1987) 8) nutrient dynamics (DeAngelis 1992) Some population interactions (e.g. competition, predation) cannot be fully evaulated outside of a foodweb context because their outcomes can be modified by other members of the web. Aquatic ecologists have acheived notable success by studying the interactions between top-down(consumption) and bottom-up (production) factors in the regulation of community structure(Carpenter 1988; McQueen et.al.1989; Power 1990a, 1990b; Vanni & Findlay 1990; Vanni et.al.1990; Persson et.al.this volume). Most foodweb studies have viewed consumption exclusively withi pathways derived from primary production, and only recently has has the major role of detritus in ecosystem structure and function received much serious attention(Cousins 1980; Rich 1984; Coleman et.al.1988; Moore et.al.1989a; Polis & Hurd, this volume; Porter, this volume). There is currently little agreement on how to best characterise the role of detritus (itself a heterogeneous unit) in foodwebs (Rich 1984; Cousins 1985; Winemiller 190; Polis 1991). In addition, foodwebs are the arenas for several major theoretical debates, such as paradigms associating complexity with stability (MacArthur 1972; May 1975, 1983; Pimm 1982; Abrams & Taber 1982) and hypotheses relating the effects of size-dependent preadtion to community structure (Brooks & Dodson 1965; Warren & Lawton 1987; Cohen & New man 1988).
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Turner, K. T., J. Bergh, A. Barendregt, J. Straaten, and E. Maltby. Ecological-economic analysis of wetlands: scientific integration for management and policy. Ecological Economics
Article
  • Feb 2000
  • ECOL ECON
Wetlands all over the world have been lost or are threatened in spite of various international agreements and national policies. This is caused by: (1) the public nature of many wetlands products and services; (2) user externalities imposed on other stakeholders; and (3) policy intervention failures that are due to a lack of consistency among government policies in different areas (economics, environment, nature protection, physical planning, etc.). All three causes are related to information failures which in turn can be linked to the complexity and ‘invisibility’ of spatial relationships among groundwater, surface water and wetland vegetation. Integrated wetland research combining social and natural sciences can help in part to solve the information failure to achieve the required consistency across various government policies. An integrated wetland research framework suggests that a combination of economic valuation, integrated modelling, stakeholder analysis, and multi-criteria evaluation can provide complementary insights into sustainable and welfare-optimising wetland management and policy. Subsequently, each of the various components of such integrated wetland research is reviewed and related to wetland management policy.
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Environmental control of food web structure. Ecology
Article
  • Apr 1983
The structure of 40 real food webs, representing aquatic and terrestrial communities from all latitudes, is found to be markedly affected by the degree of variability of the physical environment. In particular, food webs in fluctuating ecosystems are characterized by a significantly lower connectance than webs representative of more constant systems. This is interpreted within the context of stability theory as a means to optimize feeding in the face of increasing disturbance. It is shown further than the nature of the habitat itself imposes additional constraints on food web structure in intertidal, pelagic, estuarine and forest ecosystems.
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Food Webs and Niche Space
Article
  • Feb 1978
  • Monogr Popul Biol
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