Beta diversity along environmental gradients: implications of habitat specialization in tropical montane landscapes
Article first published online: 20 NOV 2008
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Journal of Animal Ecology
Volume 78, Issue 2, pages 315–327, March 2009
How to Cite
Jankowski, J. E., Ciecka, A. L., Meyer, N. Y. and Rabenold, K. N. (2009), Beta diversity along environmental gradients: implications of habitat specialization in tropical montane landscapes. Journal of Animal Ecology, 78: 315–327. doi: 10.1111/j.1365-2656.2008.01487.x
- Issue published online: 9 FEB 2009
- Article first published online: 20 NOV 2008
- Received 24 March 2007; accepted 1 September 2008; Handling Editor: Peter Bennett
- cloud forest;
- endemic species;
- reserve design;
- tropical birds
- 1Understanding how species in a diverse regional pool are spatially distributed with respect to habitat types is a longstanding problem in ecology. Tropical species are expected to be specialists along environmental gradients, and this should result in rapid compositional change (high beta diversity) across landscapes, particularly when alpha diversity is a small fraction of regional diversity. Corollary challenges are then to identify controlling environmental variables and to ask whether species cluster into discrete community types along a gradient.
- 2We investigated patterns of avian species’ distributions in the Tilarán mountains of Costa Rica between 1000 m and 1700 m elevation where a strong moisture gradient exists. High beta diversity was found with both auditory counts adjusted for detectability and extensive capture data, revealing nearly complete change in community composition over a few kilometres on the Pacific slope. As predicted, this beta diversity was roughly twice as high as on temperate mountainsides.
- 3Partial Mantel analyses and canonical correspondence analysis indicate that change in species composition is highly correlated with change in moisture (and correlated epiphyte cover) at different distances from the continental divide on the Pacific slope. Altitude was not a good predictor of change in species composition, as species composition varies substantially among sites at the same elevation.
- 4Detrended correspondence analysis and cluster analysis revealed a zone of rapid transition separating a distinct cloud forest community from rainshadow forest. On the Caribbean slope, where a shallower moisture gradient was predicted to result in lower beta diversity, we found lower rates of compositional change and more continuous species turnover.
- 5Results suggest that habitat specialization of birds is likely a strong ecological force generating high beta diversity in montane landscapes. Despite overall rapid rates of species turnover, zones of relatively coherent composition could be identified.
- 6Landscapes with such high beta diversity are common in the tropics, although little studied. They offer high benefit/cost opportunities for conservation, particularly as climate change threatens to alter the species composition of communities of habitat specialists.