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Outline

We have organized our research in a series of hierarchical questions, which in their sum will yield a broad theoretical framework on how changes in the hydrologic regime affect biological communities and ecosystem function.

We conduct replicated experiments over geographical scales that encompass substantial turnover in species composition. We experimentally change precipitation entering bromeliad ecosystems in 3 field sites covering the range of faunal diversity in general in the Americas:  French Guiana (latitude 5°N, Petit-Saut Field Station; the centre of bromeliad radiation and a hotspot for Rain shelterbromeliad faunal diversity, Costa Rica (10°N, Pitilla Field Station) which has a moderate species pool, and Puerto Rico (18°N, Luquillo LTER Field Station), a Caribbean site with a depauperate species pool.

The precipitation treatments differ in two ways: the mean amount of rainfall per day (mu) and the frequency of large versus small rainfall events (k, the dispersion parameter).

Response variables include food-web structure (changes in the composition and abundance of aquatic microorganisms and macro-invertebrates, and terrestrial arthropods) and food-web functions (carbon and nitrogen dynamics, decomposition, methane and CO2 emission).

We use innovative experimental designs to partition any differences between countries in these response variables into effects of biogeography vs. environmental conditions, and then to further partition biogeographical effects into effects moderated by species' physiological tolerances vs. species interactions. 



Last updated February 6, 2013


Université Toulouse III - Paul Sabatier - 118 route de Narbonne 31062 TOULOUSE CEDEX 9 téléphone +33 (0)5 61 55 66 11