96th ESA Annual Meeting (August 7 -- 12, 2011)

Friday, August 12, 2011: 8:40 AM

17A, Austin Convention Center

Cory C. Cleveland, Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, MT, Alan R. Townsend, INSTAAR and Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, Silvia Alvarez-Clare, Department of Ecosystem and Conservation Sciences, The University of Montana, Missoula, MT, Mercedes MMC Bustamante, Universidade de Brasilia, Brasilia, Brazil, George B. Chuyong, Plant and Animal Sciences, University of Buea, Buea, Cameroon, Solomon Dobrowski, College of Forestry and Conservation, University of Montana, Missoula, MT, Pauline Grierson, School of Biological Sciences, The University of Western Australia, Perth, Australia, Kyle E. Harms, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, Benjamin Z. Houlton, Land, Air and Water Resources, University of California, Davis, Davis, CA, Alison R. Marklein, Land, Air, Water Resources, University of California - Davis, Davis, CA, William J. Parton, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, Stephen Porder, Institute at Brown for Environment & Society, Brown University, Providence, RI, Sasha C. Reed, Southwest Biological Science Center, U.S. Geological Survey, Moab, UT, Carlos Sierra, Department of Biological Processes, Max-Planck-Institute for Biogeochemistry, Jena, Germany, Whendee L. Silver, Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, E.V.J. Tanner, Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom, Philip G. Taylor, Nicholas School of the Environment, Duke University, Durham, NC and William R. Wieder, University of Colorado, Boulder, Boulder, CO

Background/Question/Methods

Tropical forests play a dominant role in the global carbon (C) cycle, and currently buffer increases in atmospheric carbon dioxide (CO₂). Predicting the long-term fate of the tropical forest C sink requires an understanding of how climate change may alter the balance between C uptake and losses, yet our ability to predict how tropical forests may respond to changes in temperature and precipitation predicted by many climate models is limited. While climate and nutrient availability regulate net primary production (NPP) and decomposition in all terrestrial ecosystems, the nature and extent of such controls in tropical forests remain poorly resolved. Assessing the effects of climate change on tropical forests is challenged by the difficulties of conducting manipulative experiments at the scale necessary to provide information on whole-ecosystem C pools and fluxes. Thus, we conducted a meta-analysis of C-climate-nutrient interactions using data from 113 sites across the tropical forest biome in an attempt to indirectly examine possible relationships between NPP, climate, and nutrient availability.

Results/Conclusions

Our analyses showed that mean annual temperature was the strongest predictor of aboveground NPP (ANPP) across all tropical forests, but this relationship was driven by distinct temperature differences between upland and lowland forests. In contrast to the effects of temperature, ANPP was not related to mean annual precipitation. Within lowland forests alone (< 1000 m), ANPP did not vary significantly with mean annual temperature, precipitation or soil nutrient concentrations, but did vary significantly with foliar phosphorus (P) concentrations. In addition, foliar P, foliar nitrogen (N), litter decomposition rate (k), soil N and soil respiration all correlated with total surface (0-10 cm) soil P concentrations. Our results support the notion that P availability both directly and indirectly regulates NPP and other ecosystem processes in lowland tropical forests, and underscores the need for a series of large-scale nutrient manipulation experiments spanning important climatic gradients – especially in lowland forests – to further elucidate the most important climate and nutrient interactions and controls on the tropical C cycle.

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OOS 47-3 - Climate and nutrient regulation of the tropical forest carbon cycle