The Role of Biodiversity

Abstract

Human activities have caused widespread loss of biodiversity raising concern about the potential impact on ecosystem processes (flows of energy and materials). A large body of recent research has shown that as species are lost from ecosystems there is, generally, a minor impact on ecosystem processes, but that this impact increases disproportionately as species diversity declines. Functional complementarity among species, due to variation in the ecological niches they occupy, appears to be the main mechanism driving this pattern. Species diversity is also usually positively related to ecosystem stability, i.e. their variation through time and the resistance and resilience to perturbation. These findings are already powerful arguments for the conservation of biodiversity, though current research aims to increase their relevance to the real world by including a more extensive range of ecosystems and processes, realistic food web structures, realistic (nonrandom) extinction scenarios and larger spatial scales.

Keywords: ecosystem functioning; ecosystem stability; species diversity; conservation biology

Figure 1.

(a) The influence of functional complementarity (nonoverlapping niche space) and redundancy (overlapping niche space) on the shape of the diversity – ecosystems functioning relationship and (b) differences among species in their impact on a function lead to an idiosyncratic relationship depending on the actual order of species assembly. The relationship can take a variety of trajectories within a broad envelope of response (the shaded area) depending on assembly order.

Figure 2.

Mechanisms underlying diversity – stability relationships: increasing species richness results in more stable (reduced temporal variability, here measured as the coefficient of variation CV) community attributes, such as total community biomass, as long as there is some asynchrony, a mechanism termed the portfolio effect. Negative covariance in species abundances, which is expected in communities of strongly competing species, also has a stabilizing effect on community attributes, sometimes termed the negative covariance or compensatory dynamics effect.

Figure 3.

Contrasting responses of population and community stability to increased species richness. In moving from the bottom panel to the top panel, species richness increases from two to five and mean temporal variability in biomass of the populations increases. However, the community stability (aggregate biomass) increases due to averaging effects.

Figure 4.

Ecosystem multifunctionality requires higher levels of diversity than single functions alone. Grey points show numbers of species required for all possible combinations of ecosystem processes and lines are predictions based on the mean number of species required for a single process and the average overlap in the sets of species required for each pair of processes. Amended from Hector A and Bagchi R (2007) Biodiversity and ecosystem multifunctionality. Nature448 188–190.

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Further Reading

Balvanera P, Pfisterer AB, Buchmann N et al. (2006) Quantifying the evidence for biodiversity effects on ecosystem functioning and services. Ecology Letters 9: 1146–1156.

Cardinale BJ, Srivastava DS, Emmett Duffy J et al. (2006) Effects of biodiversity on the functioning of trophic groups and ecosystems. Nature 443: 989–982.

Cardinale BJ, Wright JP, Cadotte MW et al. (2007) Impacts of plant diversity on biomass production increase through time due to species complementarity: a meta‐analysis of 44 experiments. Proceedings of the National Academy of Sciences of the USA 104: 18123–18128.

Hector A and Bagchi R (2007) Biodiversity and ecosystem multifunctionality. Nature 448: 188–190.

Ives AR and Carpenter SR (2007) Stability and diversity of ecosystems. Science 317: 58–62.

Kinzig A, Tilman D and Pacala S (eds) (2002) The Functional Consequences of Biodiversity: Empirical Progress and Theoretical Extensions. Princeton: Princeton University Press.

Loreau M and Hector A (2001) Partitioning selection and complementarity in biodiversity experiments. Nature 412: 72–76 [erratum: 413 548].

Loreau M, Naeem S, Inchausti P, Bengtsson J et al. (2001) Biodiversity and ecosystem functioning: current knowledge and future challenges. Science 294: 804–809.

Loreau M, Naeem S and Inchausti P (eds) (2002) Biodiversity and Ecosystem Functioning: Synthesis and Perspectives. Oxford: Oxford University Press.

Worm B, Barbier EB, Nicola Beaumont et al. (2006) Impacts of biodiversity loss on ocean ecosystem services. Science 314: 787–790.

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How to Cite close
Wilby, Andrew, and Hector, Andy(Dec 2008) The Role of Biodiversity. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0021228]