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Year: 2005
Effects of biodiversity on ecosystem functioning: a consensus of
current knowledge
Hooper, D U; Chapin III, F S; Ewel, J J; Hector, A; Inchausti, P; Lavorel, S; Lawton, J
H; Lodge, D M; Loreau, M; Naeem, S; Schmid, B; Setälä, H; Symstad, A J;
Vandermeer, J; Wardle, D A
Hooper, D U; Chapin III, F S; Ewel, J J; Hector, A; Inchausti, P; Lavorel, S; Lawton, J H; Lodge, D M; Loreau, M;
Naeem, S; Schmid, B; Setälä, H; Symstad, A J; Vandermeer, J; Wardle, D A. Effects of biodiversity on ecosystem
functioning: a consensus of current knowledge. Ecological Monographs 2005, 75(1):3-35.
Postprint available at:
http://www.zora.unizh.ch
Posted at the Zurich Open Repository and Archive, University of Zurich.
http://www.zora.unizh.ch
Originally published at:
Ecological Monographs 2005, 75(1):3-35
Hooper, D U; Chapin III, F S; Ewel, J J; Hector, A; Inchausti, P; Lavorel, S; Lawton, J H; Lodge, D M; Loreau, M;
Naeem, S; Schmid, B; Setälä, H; Symstad, A J; Vandermeer, J; Wardle, D A. Effects of biodiversity on ecosystem
functioning: a consensus of current knowledge. Ecological Monographs 2005, 75(1):3-35.
Postprint available at:
http://www.zora.unizh.ch
Posted at the Zurich Open Repository and Archive, University of Zurich.
http://www.zora.unizh.ch
Originally published at:
Ecological Monographs 2005, 75(1):3-35
Effects of biodiversity on ecosystem functioning: a consensus of
current knowledge
Abstract
Humans are altering the composition of biological communities through a variety of activities that
increase rates of species invasions and species extinctions, at all scales, from local to global. These
changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but
they also have a strong potential to alter ecosystem properties and the goods and services they provide to
humanity. Ecological experiments, observations, and theoretical developments show that ecosystem
properties depend greatly on biodiversity in terms of the functional characteristics of organisms present
in the ecosystem and the distribution and abundance of those organisms over space and time. Species
effects act in concert with the effects of climate, resource availability, and disturbance regimes in
influencing ecosystem properties. Human activities can modify all of the above factors; here we focus
on modification of these biotic controls.
The scientific community has come to a broad consensus on many aspects of the relationship between
biodiversity and ecosystem functioning, including many points relevant to management of ecosystems.
Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem
properties, how ecological communities are structured, and the forces driving species extinctions and
invasions. To strengthen links to policy and management, we also need to integrate our ecological
knowledge with understanding of the social and economic constraints of potential management
practices. Understanding this complexity, while taking strong steps to minimize current losses of
species, is necessary for responsible management of Earth's ecosystems and the diverse biota they
contain.
Based on our review of the scientific literature, we are certain of the following conclusions:
1)Species' functional characteristics strongly influence ecosystem properties. Functional characteristics
operate in a variety of contexts, including effects of dominant species, keystone species, ecological
engineers, and interactions among species (e.g., competition, facilitation, mutualism, disease, and
predation). Relative abundance alone is not always a good predictor of the ecosystem-level importance
of a species, as even relatively rare species (e.g., a keystone predator) can strongly influence pathways
of energy and material flows.
2)Alteration of biota in ecosystems via species invasions and extinctions caused by human activities has
altered ecosystem goods and services in many well-documented cases. Many of these changes are
difficult, expensive, or impossible to reverse or fix with technological solutions.
3)The effects of species loss or changes in composition, and the mechanisms by which the effects
manifest themselves, can differ among ecosystem properties, ecosystem types, and pathways of
potential community change.
4)Some ecosystem properties are initially insensitive to species loss because (a) ecosystems may have
multiple species that carry out similar functional roles, (b) some species may contribute relatively little
to ecosystem properties, or (c) properties may be primarily controlled by abiotic environmental
conditions.
5)More species are needed to insure a stable supply of ecosystem goods and services as spatial and
temporal variability increases, which typically occurs as longer time periods and larger areas are
considered.
We have high confidence in the following conclusions:
1)Certain combinations of species are complementary in their patterns of resource use and can increase
average rates of productivity and nutrient retention. At the same time, environmental conditions can
influence the importance of complementarity in structuring communities. Identification of which and
how many species act in a complementary way in complex communities is just beginning.
2)Susceptibility to invasion by exotic species is strongly influenced by species composition and, under
similar environmental conditions, generally decreases with increasing species richness. However,
several other factors, such as propagule pressure, disturbance regime, and resource availability also
strongly influence invasion success and often override effects of species richness in comparisons across
different sites or ecosystems.
3)Having a range of species that respond differently to different environmental perturbations can
stabilize ecosystem process rates in response to disturbances and variation in abiotic conditions. Using
practices that maintain a diversity of organisms of different functional effect and functional response
types will help preserve a range of management options.
Uncertainties remain and further research is necessary in the following areas:
1)Further resolution of the relationships among taxonomic diversity, functional diversity, and
community structure is important for identifying mechanisms of biodiversity effects.
2)Multiple trophic levels are common to ecosystems but have been understudied in
biodiversity/ecosystem functioning research. The response of ecosystem properties to varying
composition and diversity of consumer organisms is much more complex than responses seen in
experiments that vary only the diversity of primary producers.
3)Theoretical work on stability has outpaced experimental work, especially field research. We need
long-term experiments to be able to assess temporal stability, as well as experimental perturbations to
assess response to and recovery from a variety of disturbances. Design and analysis of such experiments
must account for several factors that covary with species diversity.
4)Because biodiversity both responds to and influences ecosystem properties, understanding the
feedbacks involved is necessary to integrate results from experimental communities with patterns seen
at broader scales. Likely patterns of extinction and invasion need to be linked to different drivers of
global change, the forces that structure communities, and controls on ecosystem properties for the
development of effective management and conservation strategies.
5)This paper focuses primarily on terrestrial systems, with some coverage of freshwater systems,
because that is where most empirical and theoretical study has focused. While the fundamental
principles described here should apply to marine systems, further study of that realm is necessary.
Despite some uncertainties about the mechanisms and circumstances under which diversity influences
ecosystem properties, incorporating diversity effects into policy and management is essential, especially
in making decisions involving large temporal and spatial scales. Sacrificing those aspects of ecosystems
that are difficult or impossible to reconstruct, such as diversity, simply because we are not yet certain
about the extent and mechanisms by which they affect ecosystem properties, will restrict future
management options even further. It is incumbent upon ecologists to communicate this need, and the
values that can derive from such a perspective, to those charged with economic and policy
decision-making.
3
Ecological Monographs,
75(1), 2005, pp. 3–35
q
2005 by the Ecological Society of America
ESA Report
EFFECTS OF BIODIVERSITY ON ECOSYSTEM FUNCTIONING:
A CONSENSUS OF CURRENT KNOWLEDGE
D. U. H
OOPER
,
1,16
F. S. C
HAPIN
, III,
2
J. J. E
WEL
,
3
A. H
ECTOR
,
4
P. I
NCHAUSTI
,
5
S. L
AVOREL
,
6
J. H. L
AWTON
,
7
D. M. L
ODGE
,
8
M. L
OREAU
,
9
S. N
AEEM
,
10
B. S
CHMID
,
4
H. S
ETA
¨
LA
¨
,
11
A. J. S
YMSTAD
,
12
J. V
ANDERMEER
,
13
AND
D. A. W
ARDLE
14,15
1
Department of Biology, Western Washington University, Bellingham, Washington 98225 USA
2
Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775 USA
3
Institute of Pacific Islands Forestry, Pacific Southwest Research Station, USDA Forest Service, 1151 Punchbowl Street,
Room 323, Honolulu, Hawaii 96813 USA
4
Institute of Environmental Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zu¨rich, Switzerland
5
CEBC-CNRS, 79360 Beauvoir-sur-Niort, France
6
Laboratoire d’Ecologie Alpine, CNRS UMR 5553, Universite´ J. Fourier, BP 53, 38041 Grenoble Cedex 9, France
7
Natural Environment Research Council, Polaris House, North Star Avenue, Swindon SN2 1EU, UK
8
Department of Biological Sciences, P.O. Box 369, University of Notre Dame, Notre Dame, Indiana 46556-0369 USA
9
Laboratoire d’Ecologie, UMR 7625, Ecole Normale Supe´rieure, 46 rue d’Ulm, 75230 Paris Cedex 05, France
10
Department of Ecology, Evolution and Environmental Biology, Columbia University, 1200 Amsterdam Avenue,
New York, New York 10027 USA
11
University of Helsinki, Department of Ecological and Environmental Sciences, Niemenkatu 73, FIN-15140 Lahti, Finland
12
U.S. Geological Survey, Mount Rushmore National Memorial, 13000 Highway 244, Keystone, South Dakota 57751 USA
13
Department of Biology, University of Michigan, Ann Arbor, Michigan 48109 USA
14
Landcare Research, P.O. Box 69, Lincoln, New Zealand
15
Department of Forest Vegetation Ecology, Swedish University of Agricultural Sciences, SE901-83, Umea˚, Sweden
Abstract.
Humans are altering the composition of biological communities through a
variety of activities that increase rates of species invasions and species extinctions, at all
scales, from local to global. These changes in components of the Earth’s biodiversity cause
concern for ethical and aesthetic reasons, but they also have a strong potential to alter
ecosystem properties and the goods and services they provide to humanity. Ecological
experiments, observations, and theoretical developments show that ecosystem properties
depend greatly on biodiversity in terms of the functional characteristics of organisms present
in the ecosystem and the distribution and abundance of those organisms over space and
time. Species effects act in concert with the effects of climate, resource availability, and
disturbance regimes in influencing ecosystem properties. Human activities can modify all
of the above factors; here we focus on modification of these biotic controls.
The scientific community has come to a broad consensus on many aspects of the re-
lationship between biodiversity and ecosystem functioning, including many points relevant
to management of ecosystems. Further progress will require integration of knowledge about
biotic and abiotic controls on ecosystem properties, how ecological communities are struc-
tured, and the forces driving species extinctions and invasions. To strengthen links to policy
and management, we also need to integrate our ecological knowledge with understanding
of the social and economic constraints of potential management practices. Understanding
this complexity, while taking strong steps to minimize current losses of species, is necessary
for responsible management of Earth’s ecosystems and the diverse biota they contain.
Manuscript received 2 June 2004; accepted 7 June 2004; final version received 7 July 2004. Corresponding Editor (ad hoc): J. S.
Denslow. This article is a committee report commissioned by the Governing Board of the Ecological Society of America. Reprints
of this 33-page ESA report are available for $5.00 each, either as pdf files or as hard copy. Prepayment is required. Order reprints
from the Ecological Society of America, Attention: Reprint Department, 1707 H Street, N.W., Suite 400, Washington, DC 20006
USA (e-mail: esaHQ@esa.org).
16
E-mail: hooper@biol.wwu.edu
4
ESA REPORT
Ecological Monographs
Vol. 75, No. 1
Based on our review of the scientific literature, we are certain of the following con-
clusions:
1) Species’ functional characteristics strongly influence ecosystem properties. Func-
tional characteristics operate in a variety of contexts, including effects of dominant species,
keystone species, ecological engineers, and interactions among species (e.g., competition,
facilitation, mutualism, disease, and predation). Relative abundance alone is not always a
good predictor of the ecosystem-level importance of a species, as even relatively rare species
(e.g., a keystone predator) can strongly influence pathways of energy and material flows.
2) Alteration of biota in ecosystems via species invasions and extinctions caused by
human activities has altered ecosystem goods and services in many well-documented cases.
Many of these changes are difficult, expensive, or impossible to reverse or fix with tech-
nological solutions.
3) The effects of species loss or changes in composition, and the mechanisms by which
the effects manifest themselves, can differ among ecosystem properties, ecosystem types,
and pathways of potential community change.
4) Some ecosystem properties are initially insensitive to species loss because (a) eco-
systems may have multiple species that carry out similar functional roles, (b) some species
may contribute relatively little to ecosystem properties, or (c) properties may be primarily
controlled by abiotic environmental conditions.
5) More species are needed to insure a stable supply of ecosystem goods and services
as spatial and temporal variability increases, which typically occurs as longer time periods
and larger areas are considered.
We have high confidence in the following conclusions:
1) Certain combinations of species are complementary in their patterns of resource use
and can increase average rates of productivity and nutrient retention. At the same time,
environmental conditions can influence the importance of complementarity in structuring
communities. Identification of which and how many species act in a complementary way
in complex communities is just beginning.
2) Susceptibility to invasion by exotic species is strongly influenced by species com-
position and, under similar environmental conditions, generally decreases with increasing
species richness. However, several other factors, such as propagule pressure, disturbance
regime, and resource availability also strongly influence invasion success and often override
effects of species richness in comparisons across different sites or ecosystems.
3) Having a range of species that respond differently to different environmental perturbations
can stabilize ecosystem process rates in response to disturbances and variation in abiotic con-
ditions. Using practices that maintain a diversity of organisms of different functional effect and
functional response types will help preserve a range of management options.
Uncertainties remain and further research is necessary in the following areas:
1) Further resolution of the relationships among taxonomic diversity, functional diversity,
and community structure is important for identifying mechanisms of biodiversity effects.
2) Multiple trophic levels are common to ecosystems but have been understudied in
biodiversity/ecosystem functioning research. The response of ecosystem properties to vary-
ing composition and diversity of consumer organisms is much more complex than responses
seen in experiments that vary only the diversity of primary producers.
3) Theoretical work on stability has outpaced experimental work, especially field re-
search. We need long-term experiments to be able to assess temporal stability, as well as
experimental perturbations to assess response to and recovery from a variety of disturbances.
Design and analysis of such experiments must account for several factors that covary with
species diversity.
4) Because biodiversity both responds to and influences ecosystem properties, under-
standing the feedbacks involved is necessary to integrate results from experimental com-
munities with patterns seen at broader scales. Likely patterns of extinction and invasion
need to be linked to different drivers of global change, the forces that structure communities,
and controls on ecosystem properties for the development of effective management and
conservation strategies.
5) This paper focuses primarily on terrestrial systems, with some coverage of freshwater
systems, because that is where most empirical and theoretical study has focused. While the
![FIG. 3. Variation in effects of plant species richness and composition on plant productivity. (A) Experiments in the tropics. Treatments ran for five years and included four monocultures (two rotations [1st and 2nd] of maize [Zea mays], one rotation of cassava [Manihot esculenta], and one rotation of a tree, Cordia alliodora); a diverse (.100 plant species) natural succession following clearing and burning of original vegetation; a species-enriched (;120 species) version of natural succession; and an imitation of succession that mimicked the plant life forms in the natural succession treatment, but with different species. Monocultures were timed to coincide with growth phases of natural succession: maize during the initial herbaceous stage, cassava during the shrub-dominated stage, and C. alliodora during the tree-dominated stage. Note that the maize monoculture had both the highest and lowest overall productivity, and that the productivity of the successional vegetation was not increased by further increases in species richness. This figure is modified from Ewel (1999). (B) The pan-European BIODEPTH experiment. At several sites, plant productivity increased with increasing species richness, although the pattern of response varied in individual location analyses. Five of the sites had either non-saturating or saturating patterns (on a linear scale). At two sites significant differences across different levels of diversity (ANOVA) provided a better model than a linear regression. One site (Greece, dotted line) showed no significant relationship between aboveground plant productivity and species richness. Even where there are strong trends in the diversity effect, there is also variation within levels of richness resulting in part from differences in composition. Points are individual plot biomass values, and lines are regression curves or join diversity level means (squares for Ireland and Silwood). The figure is after Hector et al. (1999).](/figures/fig-3-variation-in-effects-of-plant-species-richness-and-12hd8gme.webp)
![FIG. 5. Increasing stability with increasing species richness in ecological experiments. In both cases, the overall patterns are as predicted from theory, but the underlying mechanisms may coincide only in part (see Section II.B.2). (A) Temporal variability (coefficient of variation, CV) in aboveground plant biomass (correlated with productivity in these Minnesota grasslands) in response to climatic variability (the figure is from Tilman [1999]). The gradient in species richness results from different levels of nutrient addition, so that the stability response may result from differences in species composition instead of, or in addition to, compensatory responses among species (Givnish 1994, Huston 1997). (B) Standard deviation (SD) of net ecosystem CO2 flux in a microbial microcosm (the figure is from McGrady-Steed et al. [1997]). The decrease in variability with increasing diversity may result from both decreased temporal variability and increased compositional similarity among replicates. See also Morin and McGrady-Steed (2004). Composite figure after Loreau et al. (2001).](/figures/fig-5-increasing-stability-with-increasing-species-richness-1kvvusm8.webp)
