Print PageTropical forests play a major role in regulating global C fluxes and stocks, and even small changes to C cycling in this productive biome could dramatically affect atmospheric CO2 concentrations. Temperature is expected to increase considerably over all land-surfaces, yet we have a surprisingly poor understanding of how tropical forests will respond to this significant climatic change. Here we present a contemporary synthesis of the existing data and what they suggest about how tropical forests will respond to increasing temperatures.
Results/Conclusions
Over the last decade, controversies over the primary forces that are driving changes in tropical forest C-balance have been heated, with all sides giving valid evidence for and against contrasting theories. We suggest two main reasons for this. First, research conducted at different spatial and temporal scales often leads to contradicting conclusions. Large-scale observational studies confound multiple climatic, edaphic, and biotic factors, while small-scale studies cannot address the interconnectedness of above- and belowground processes and are challenging to scale to the ecosystem. Second, tropical forests vary enormously in ways we know to be critical to regulating function, and it is highly unlikely that all tropical forests will respond in the same way. We suggest experimental approaches to further elucidate how tropical forests will respond to warming, including whole-forest manipulation experiments, longer-term experiments, the incorporation of a range of scales in the investigation of warming effects, and the inclusion of a diversity of tropical forest sites. Finally, we highlight areas of tropical forest research where almost no data are available, including temperature effects on: nutrient cycling, heterotrophic vs. autotrophic respiration, thermal adaptation vs. substrate limitation of plant and microbial communities, belowground C-allocation, species composition (plant and microbial), and hydraulic architecture of roots. Whether or not tropical forests will become a source or a sink of C in warmer world remains highly uncertain. Given the importance of these ecosystems to the global C budget, resolving this uncertainty remains a high research priority.
