Amazon Forest Dynamics and Carbon Balance 1980-2005
Phillips and RAINFOR Consortium, University of Leeds and RAINFOR Consortium, email@example.com
Evidence from long-term permanent plots indicates a number of changes have occurred in the ecological structure and dynamics of mature Amazon forests over at least the last two to three decades. These changes - including changes in dynamic processes (e.g., increased mortality, increased wood production) and static properties (e.g. increased biomass) - are concerted and spatially coherent. As a consequence it appears that mature Amazon forest biomass has been acting as a substantial carbon sink for many years. The exact mechanism(s) driving these changes are not known, but the simplest explanation consistent with the available evidence is that one or more external drivers have enhanced growth.
The 21st century atmospheric setting for Amazon forests may be without precedent for tens of millions of years, but the observational plot network provides a number of clues for how we may expect near-future atmospheric changes to impact those Amazonian forests which survive direct human effects. For example, (1) Amazonian forests are functionally remarkably variable both locally and regionally. This suggests that changing turnover rates could drive changes in the functional composition of forests, with impacts on carbon storage. (2) The recent carbon sink, while significant at the global scale, actually represents at the plot-level a small difference between two large ecological terms (growth and mortality), which in turn are dwarfed by the magnitude of total carbon processed by the system. This suggests that even moderate drought may be sufficient to shut or even reverse the biomass sink. These ideas will be explored using RAINFOR data.