Shifts of community composition and population density substantially affect ecosystem function despite invariant richness |
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| Authors: | Jurg W Spaak Jan M Baert Donald J Baird Nico Eisenhauer Lorraine Maltby Francesco Pomati Viktoriia Radchuk Jason R Rohr Paul J Van den Brink Frederik De Laender |
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| Institution: | 1. Research Unit in Environmental and Evolutionary Biology, University of Namur, Namur, Belgium;2. Department of Aquatic Ecology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland;3. Behavioural Ecology and Ecophysiology Group, Department of Biology, University of Antwerp, Antwerp, Belgium;4. Terrestrial Ecology Unit, Department of Biology, University of Ghent, Ghent, Belgium;5. Department of Biology, Environment & Climate Change Canada @ Canadian Rivers Institute, University of New Brunswick, New Brunswick, Canada;6. Institute of Biology, Leipzig University, Leipzig, Germany;7. German Centre for Integrative Biodiversity Research (iDiv), Leipzig, Germany;8. Department of Animal and Plant Sciences, The University of Sheffield, Sheffield, UK;9. Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research (IZW), Berlin, Germany;10. Department of Integrative Biology, University of South Florida, Tampa, Florida, USA;11. Alterra, Wageningen University and Research centre, Wageningen, The Netherlands;12. Department of Aquatic Ecology and Water Quality Management, Wageningen University, Wageningen, The Netherlands |
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| Abstract: | There has been considerable focus on the impacts of environmental change on ecosystem function arising from changes in species richness. However, environmental change may affect ecosystem function without affecting richness, most notably by affecting population densities and community composition. Using a theoretical model, we find that, despite invariant richness, (1) small environmental effects may already lead to a collapse of function; (2) competitive strength may be a less important determinant of ecosystem function change than the selectivity of the environmental change driver and (3) effects on ecosystem function increase when effects on composition are larger. We also present a complementary statistical analysis of 13 data sets of phytoplankton and periphyton communities exposed to chemical stressors and show that effects on primary production under invariant richness ranged from ?75% to +10%. We conclude that environmental protection goals relying on measures of richness could underestimate ecological impacts of environmental change. |
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| Keywords: | Algae biodiversity coexistence community ecology modelling primary production |
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