Understanding Carbon Fluxes in a Changing Amazon from 2014 to 2020

这个项目的重点是研究亚马逊的碳通量和人为火灾对亚马逊碳循环的影响。最先进的二氧化碳（CO2）通量模型将与来自多个平台的数据一起使用，以改进对亚马逊地区碳预算的了解。研究结果将有助于决策者和研究人员更好地了解生态系统在多个时间尺度上的反应，并有助于确定改进的森林管理措施。该项目的目标是探索日益受到干扰的亚马逊地区生物圈碳通量是如何变化的，以及人为火灾活动的增加是否正在成为（亚）区域陆地-大气碳交换的主要模式。本文研究的两个主要假设是：(1)2014-2020年亚马孙流域土地碳汇强度总体呈下降趋势，延续了上世纪90年代至2011年的下降趋势；(2)在年尺度上，旱季人为火活动的增加正在发生明显变化，表明未来（亚）区域陆地-大气碳交换的主导模式将从以总初级生产力（GPP）为主导向以GPP和火为主导转变。基于植被、光合作用和呼吸模型（VPRM）的数据驱动的生物圈二氧化碳（CO2）表面通量模型将使用与光合作用高度相关的太阳诱导荧光（SIF）参数驱动。新获得的生物质燃烧CO排放量将与火灾CO2/CO排放比结合使用，以估计火灾对整个生物圈主导的CO2信号的相对重要性的变化。最近获得的数据，包括轨道碳观测站（OCO-2）的二氧化碳观测和其他生态系统产品，将使热带生物圈对气候变率的碳响应更容易在多个时空尺度上量化。通过这项研究开发的改进的亚马逊地区二氧化碳表面通量模型将有助于确定大气测量是否可以用于获得对当前和未来生态系统对当地和全球变化驱动因素的响应的自上而下的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.