Understanding Carbon Fluxes in a Changing Amazon from 2014 to 2020

该项目的重点是研究亚马逊的碳通量以及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，以提高对亚马逊地区碳预算的理解。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响应，并帮助确定改进的森林管理practices.The项目的目标是探索如何生物圈碳通量在日益受到干扰的亚马逊正在发生变化，以及是否增加人为火灾活动正在成为（分）区域土地-大气碳交换的主导模式。本研究的两个主要假设是：（1）2014-2020年亚马逊陆地碳汇强度总体呈下降趋势，延续了20世纪90年代至2011年的下降趋势;（2）在年度尺度上，旱季人为火灾活动的增加正在发生明显变化，这表明，未来（分）区域陆地-大气碳交换的主导模式将从以总初级生产力（GPP）为主转变为以GPP和火为主导。光合作用和呼吸模型（VPRM）将由与光合作用高度相关的太阳诱导荧光（SIF）参数驱动。新衍生的生物质燃烧排放的CO将被用于结合火灾CO2/CO排放比，以估计火灾的相对重要性的变化，整体生物圈占主导地位的CO2信号。最近获得的数据，包括CO2观测数据和轨道碳观测站（OCO-2）提供的其他生态系统产品，将使热带生物圈对气候变化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亚马逊地区改进的CO2表面通量模型将有助于确定大气测量是否可以用于自上而下地了解当前和未来生态系统对当地和全球变化驱动因素的反应。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.