What is the role of climate in controlling the exchange of carbon and water in an Amazonian rainforest?
Hutyra, Harvard University, email@example.com
Munger, Harvard university, firstname.lastname@example.org
Saleska, university of Arizona, email@example.com
Camargo, USP/CENA, firstname.lastname@example.org
Wofsy, Harvard University, email@example.com
The stability of Amazonian equatorial forests, and the fate of their immense stores of organic carbon, depend on the ecosystem response to climate and weather. This study presents 4+ years of eddy covariance measurements of carbon and water fluxes and their response to environmental conditions in an Amazonian old-growth tropical forest. Contrary to expectations, this forest does not show signs of seasonal water limitation on growth despite a 5-month dry season. CO2 uptake responds primarily to light on hourly time scales, but photosynthesis overall maximizes in the middle of the dry season, responding to ecophysiological (flushing of new leaves) and atmospheric (high aerosol loading) changes. Annual carbon balance was very sensitive to weather anomalies, particularly the timing of the dry-to-wet seasonal transition, with mean net loss of 939 kg C ha-1 yr-1 (observed range of -221 (uptake) to 2677 (loss) kg C ha-1 yr-1). The climatic sensitivity has significant implications for Amazonian carbon balances on annual to decadal time scales.