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Task 5.1.2. Scaling between fine and large scales

Task lead: Nick Zimmermann, Eidgenössische Forschungsanstalt, WSL, CH

Our results demonstrated that scale effects are largely responsible for high disagreement on altitudinal variations of species richness in the literature and the lack of consensus on the mechanisms controlling them. Such scale effect is suspected to be due to human impacts at low and high elevations, emphasizing that human activities prevent to reach a clear understanding of natural biodiversity patterns. Scale effects appeared not only to be important in our perception of biodiversity patterns but also in our ability to model them.

Indeed, through the second topic of investigation, it has been clearly demonstrated that scale affect the accuracy of species distribution predictions, the species range size and even spatial locations of predicted species presences. This has profound implications on the use of Species Distribution Models for conservation especially in the context of selection of protected areas.

Finally, it has been shown that species shift forecasts with global change (e.g. species extinction/persistence rates) may greatly differ whether using global or local scale models. However, further investigation is needed to clearly understand why such discrepancy was observed.

  • Nogués-Bravo, D., Araújo, M.B., Romdal, T., and Rahbek, C. 2008 Scale effects and human impact on the elevational species richness gradients. Nature 453:216-220.
  • Seo, C., Thorne, J.H., Hannah, L., and Thuiller, W. (2009) Scale effects in species distribution models: implications for conservation planning under climate change. Biology Letters 5:39-43.
  • Randin, C.F., Engler, R., Normand, S., Zappa, M., Zimmermann, N.E., Pearman, P., Vittoz, P., Thuiller, W. & Guisan, A. (2009) Predicting climate change impacts on mountain plants distribution: testing the high-elevation persistence hypothesis. Gobal Change Biology, 15:1557-1569.
  • Barbet-Massin, M., Thuiller, W. and Jiguet, F. 2010 How much do we overestimate future local extinction rates when restricting the range of occurrence data in climate suitability models? Ecography.
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