Understanding Carbon Fluxes in a Changing Amazon from 2014 to 2020

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This project is focused on the study of carbon fluxes in the Amazon and the influence of human-caused fires on the Amazon carbon cycle. State-of-the-art models of carbon dioxide (CO2) flux will be used with data from multiple platforms to provide improvements to the understanding of the carbon budget for the Amazon region. The results will be useful for policymakers and researchers to better understand ecosystem responses at multiple timescales and to help identify improved forest management practices.The goals of this project are to explore how biospheric carbon fluxes in an increasingly disturbed Amazon are changing, and whether increased anthropogenic fire activity is becoming a dominant mode of (sub)regional land-atmosphere carbon exchange. The two main hypotheses to be explored in this research are: (1) The Amazon land carbon sink strength is decreasing overall from 2014–2020, continuing with the previously identified decreasing trend from the 1990s through 2011; and (2) At annual scales, increased dry-season anthropogenic fire activity is appreciably changing, suggesting that the dominant mode of future (sub)regional land-atmosphere carbon exchange will shift from gross primary productivity (GPP)-dominant to both GPP- and fire-dominant.A data-driven biospheric carbon dioxide (CO2) surface flux model, based on the Vegetation, Photosynthesis and Respiration Model (VPRM), will be driven with a solar-induced fluorescence (SIF) parameter that is highly correlated with photosynthesis. Newly derived biomass burning emissions of CO will be used in combination with fire CO2/CO emission ratios to estimate variations in the relative importance of fires to the overall biosphere-dominated CO2 signal. Recently acquired data, including CO2 observations and additional ecosystem products from the Orbiting Carbon Observatory (OCO-2) will enable the tropical biosphere’s carbon response to climatological variability to be more readily quantified at multiple spatiotemporal scales. The improved CO2 surface flux model for the Amazon developed through this research will help to determine whether atmospheric measurements can be used to gain a top-down understanding of current and future ecosystem responses to both local and global drivers of change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.