Michel Loreau
Department of Biology
May 7, 2008
The relationship between biodiversity and ecosystem functioning has emerged as a central issue in ecological and environmental sciences during the last decade. Increasing domination of ecosystems by humans is steadily transforming them into depauperate systems. Because ecosystems collectively determine the biogeochemical processes that regulate the Earth system, the potential ecological consequences of biodiversity loss have aroused considerable interest.
Recent theoretical and experimental work has showed that plant species diversity enhances the productivity of grassland ecosystems because functional complementarity among species leads to better collective resource use. Similar results have been obtained for a wide range of ecosystems. There is also theoretical and experimental evidence that biodiversity acts in the long term as biological insurance, stabilising ecosystem processes in the face of environmental changes.
The extent and complexity of biodiversity effects, however, are probably strongly underestimated by current knowledge based on simple systems and single ecosystem processes. Interactions between multiple trophic levels, spatial flows in heterogeneous landscapes and cascades of species extinctions are expected to make the relationship between biodiversity and biogeochemical processes complex and highly nonlinear.
Recent scientific advances support neither the catastrophist view that the Earth system will collapse following biodiversity loss, nor the optimistic view that nature can be further despoiled without consequences. Biodiversity loss will likely have far-reaching impacts on the functioning of the natural systems upon which we rely directly and indirectly. The extent of biodiversity loss that we are willing to accept, however, is a societal choice.