Which Comes First ... Diversity or Productivity?
One of the oldest questions in ecology is that of how species diversity relates to the productivity of ecosystems. Historically, researchers have viewed differences in biodiversity among communities or ecoregions as being a consequence of differences in levels of productivity. In recent years, ecologists have begun to view the relationship between diversity and productivity from a fundamentally different angle, examining how biodiversity controls, rather than simply responds to, the production of biomass in ecosystems. These contrasting perspectives have engendered a lively debate about whether biodiversity is the cause or the consequence of ecosystem production.
As scientists have begun to ponder how we might resolve this chicken-vs.-egg question, many have proposed that diversity and production must somehow exhibit bi-directional causality. But the mechanisms by which this might occur remain unclear.
This new project seeks to figure out how biodiversity might be both a cause and a consequence of ecosystem productivity in the same ecological system. We are taking three complimentary approaches to the problem. First, we are using meta-community theory to mathematically describe how the supply rates of resources that limit biological production can influence species coexistence and, in turn, the impacts of species extinction on the production of community biomass. Second, we plan to test key predictions from these models in simple experimental systems where we can manipulate both the rates of resource supply that limit biological production as well as the number of species in a community. Lastly, we intend to perform comparative field experiments that manipulate rates of resource supply in streams spanning both natural gradients in diversity, and gradients that occur from natural to human dominated landscapes. Collectively, these studies will help detail how biodiversity might both respond to, as well as control, the availability of key resources known to limit biological production.
| Related Publications | |
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| Cardinale, B. J., D. Bennett, C. Nelson, and K. Gross. Does productivity drive diversity or vice versa? Support for the multivariate productivity–diversity hypothesis in streams. Ecology, 90:1227-1241. |
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| Cardinale, B. J., H. Hillebrand, W. S. Harpole, K. Gross, and R. Ptacnik. 2009. Separating the influence of resource ‘availability’ from resource ‘imbalance’ on productivity-diversity relationships. Ecology Letters, 12:475-487. |
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| Gross, K. and B.J. Cardinale. 2007. Does species diversity drive ecosystem productivity or vice versa? Towards unification of the historical and contemporary paradigms. American Naturalist 170:207-220. |
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| Cardinale, B. J., J. J. Weis, K. J. Tilmon, A. E. Forbes, A. R. Ives. 2006. Biodiversity as both a cause and consequence of resource availability: A study of reciprocal causality in a predator-prey system. Journal of Animal Ecology 75:497-505. |
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Collaborators
- Kevin Gross, Biomathematics Program, North Carolina State University
Acknowledgements
'Seed' funding for this project was provided by the
Santa Barbara Coastal LTER.
National Science Foundation to fully develop this work starting March 2009