Biodiversity, Ecosystem Functioning and Scale
Over the past decade, scientists have become increasingly concerned that accelerating rates of species extinction might alter basic ecological processes that are important to humanity (see "What is biodiversity and ecosystem functioning?"). This concern has prompted an increasing number of researchers to experimentally reduce the number of species in an ecosystem and examine how loss of diversity impacts key processes like the production of community biomass. Although these studies have greatly advanced our understanding, they suffer from certain limitations. For example, studies have generally been performed in environments that are greatly over-simplified to maximize experimental control. Under these conditions, results suggest that relatively few species are needed to maximize ecological processes (summarized in Cardinale et al., Nature 2006). But a key problem is that such results conflict with a large body of ecological theory that predicts every species has a unique niche and, as a result, diverse communities should capture more resources and produce more biomass than less diverse communities.
In this project, we seek to resolve the disparity between mathematical theory and results of experiments. Specifically, we hypothesize that few species are required to maximize ecological processes at small scales that are the focus of simplified experimental systems. However, many more species are required to maximize processes at the larger scales of natural habitats where theory says diversity exists because of inherently complexity and variability.
To address this hypothesis, we are taking an empirical approach using a combination of field and laboratory experiments focused on systems of freshwater algae. First, we are using our new experimental flume facility (i.e., a system of 100 recirculating laboratory streams) to compare how the diversity of algae affects primary production and nutrient dynamics in streams that have simplified flow & disturbance regimes, to those that are more comparable to natural systems with pronounced spatial and temporal variation in these variables.
Second, we are using field experiments to manipulate the degree of flow heterogeneity & frequency of disturbance in streams spanning a large natural gradient in algal diversity. Collectively, these studies will help us determine the spatial and temporal scales of which biodiversity loss most affects vital ecosystem processes.
This work has been highlighted by The National Science Founation, CBC News, The University of California, The Smithsonian Magazine, Science Daily, NBC Local News, The Santa Barbara Independent to name a few. Our Nature 2006 publication was selected by Thomson Scientific as one of the 'hottest' new papers in environmental science. Read the interview in Science Watch.
| Related Publications | |
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| Power, L. M. and B. J. Cardinale. Species richness enhances both producer biomass and rates of primary production: Evidence from a microcosm study using freshwater algae. Oikos, in press. |
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| Hillebrand, H., and B. J. Cardinale. A critique of meta-analyses and the productivity-diversity relationship. Ecology, 12: in press. | |
| Cardinale, B. J., D. S. Srivastava, J. E. Duffy, J. P. Wright, A. L. Downing, M. Sankaran, C. Jouseau, M. W. Cadotte, I. T. Carroll, J. J. Weis, A. Hector, and M. Loreau. 2009. Effects of biodiversity on the functioning of ecosystems: A summary of 164 experimental manipulations of species richness. Ecology (Data Paper), 90:854. |
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| Srivastava, D. S., B. J. Cardinale, J. E. Duffy, J. P. Wright, A. L. Downing, M. Sankaran. 2009. Diversity controls the strength of top-down, but not bottom-up effects on decomposition. Ecology, 90:1073-1083. |
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| Cardinale, B. J., E. Duffy, D. Srivastava, M. Loreau, M. Thomas, and M. Emmerson. 2009. Towards a food-web perspective on biodiversity and ecosystem functioning, pages 105-120 in Biodiversity and Human Impacts, S. Naeem, D. Bunker, M. Loreau, A. Hector, C. Perring. Oxford University Press. | |
| Schmid, B., P. Balvanera, B. J. Cardinale, J. Godbold, A. B. Pfisterer, D. Raffaelli, M. Solan, D. S. Srivastava. 2009. Consequences of species loss for ecosystem functioning: a meta-analysis of data from biodiversity experiments, pages 14-29 in Biodiversity and Human Impacts, S. Naeem, D. Bunker, M. Loreau, A. Hector, C. Perring. Oxford University Press. |
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| Weis, J. J., D. Madrigal, and B. J. Cardinale. 2008. Effects of algal species richness on the production of community biomass in homogeneous verses heterogeneous environments. PLoS One, 3:e2825-e2825. |
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| Cadotte, M. C., B. J. Cardinale, and T. H. Oakley. 2008. Evolutionary history predicts the ecological impacts of species extinction. Proceedings of the National Academy of Science, 105:17012-17017. |
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| Cardinale, B. J., J. P. Wright, M. W. Cadotte, I. T. Carroll, A. Hector, D. S. Srivastava, M. Loreau, and J. J. Weis. 2007. Impacts of plant diversity on biomass production increase through time due to species complementarity. PNAS 104(46): 18123-18128. |
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| Duffy, J. E., B. J. Cardinale, K. E. France, M. Loreau, P. B. McIntyre, and E. Thebault. 2007. The functional role of biodiversity in food webs: Incorporating trophic complexity. Ecology Letters 10:522-538. |
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| Madritch, M. and B. J. Cardinale. 2007. Impacts of tree species diversity on litter decomposition in northern temperate forests of Wisconsin, USA: a multi-site experiment along a latitudinal gradient. Plant & Soil 292:147-159. |
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| Weis, J. J., B. J. Cardinale, and A. R. Ives. 2007. Effects of algal species richness on community biomass production change predictably through successional time. Ecology 88:929-939. |
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| Cardinale, B.J., D. S. Srivastava, J. E. Duffy, J. P. Wright, A. L. Downing, M. Sankaran, and C. Jousseau. 2006. Effects of biodiversity on the functioning of trophic groups and ecosystems. Nature 443:989-992. |
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| Cardinale, B. J., M. A. Palmer, A. R Ives, and S. S. Brooks. 2005. Diversity-productivity relationships in streams vary as a function of the natural disturbance regime. Ecology 86:716-726. |
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| Gross, K., and B. J. Cardinale. 2005. The functional consequences of random verses ordered species extinctions. Ecology Letters 8:409-418. |
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| Cardinale, B. J., A. R. Ives, and P. Inchausti. 2004. Effects of species diversity on the primary productivity of ecosystems: extending our spatial and temporal scales of inference. Oikos 104:437-450. |
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Acknowledgements
National Science Foundation