Animal diversity and ecosystem functioning in dynamic food webs.

Florian D Schneider,Ulrich Brose,Christian Guill,Björn C Rall

doi:10.1038/ncomms12718

Abstract

Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning. High animal diversity increases complementarity of herbivores but also increases feeding rates within the consumer guild. Depending on the balance of these counteracting mechanisms, species-rich animal communities may put plants under top-down control or may release them from grazing pressure. Using a dynamic food-web model with body-mass constraints, we simulate ecosystem functions of 20,000 communities of varying animal diversity. We show that diverse animal communities accumulate more biomass and are more exploitative on plants, despite their higher rates of intra-guild predation. However, they do not reduce plant biomass because the communities are composed of larger, and thus energetically more efficient, plant and animal species. This plasticity of community body-size structure reconciles the debate on the consequences of animal species loss for primary productivity.

Highlights

Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning
We lack a generalized understanding of the relationship between animal diversity and ecosystem functioning: Apparently idiosyncratic, positive as well as negative consequences for plant primary productivity in response to animal species loss from multi-trophic communities have been observed[10,11,12,13,14], which cannot be explained by species richness alone
Being based on well understood mechanisms at the population level, this is a generic approach to the functions provided at the ecosystem level[45] (Fig. 1). Using this generic model framework, we investigate whether increasing animal diversity causes stronger top–down control on the plant community via enhanced direct feeding interactions and complementarity effects, or if it rather weakens top–down control due to the increase of intraguild predation among animals

Summary

Introduction

Species diversity is changing globally and locally, but the complexity of ecological communities hampers a general understanding of the consequences of animal species loss on ecosystem functioning. We lack a generalized understanding of the relationship between animal diversity and ecosystem functioning: Apparently idiosyncratic, positive as well as negative consequences for plant primary productivity in response to animal species loss from multi-trophic communities have been observed[10,11,12,13,14], which cannot be explained by species richness alone. This dichotomy of effects may be explained by the ecosystem’s balance between niche complementarity effects and community trophic cascades[15,16,17]. In this study we employ dynamic simulations of complex food webs to assess general patterns in these community level quantities of ecosystem function in response to changes in animal diversity (Fig. 1)

Methods

Results

Conclusion