Understanding Carbon Fluxes in a Changing Amazon from 2014 to 2020

该项目的重点是研究亚马逊地区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，以改进对亚马逊地区碳预算的理解。研究结果将有助于政策制定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实践。该项目的目标是探索日益干扰的亚马逊地区的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(次)区域陆地-大气碳交换的主要模式。本研究拟探讨的两个主要假设是：(1)2014-2020年亚马逊陆地碳汇强度总体上呈下降趋势，延续了上世纪90年代至2011年的下降趋势；(2)在年尺度上，旱季人为火灾活动的增加正在发生明显的变化，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)为主转变为以GPP和火为主。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)表面通量模型将由与光合作用高度相关的太阳诱导荧光(SIF)参数驱动。新得出的生物质燃烧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二氧化碳信号的相对重要性的变化。最近获得的数据，包括二氧化碳观测和轨道碳观测站(OCO-2)的其他生态系统产品，将使热带生物圈对气候变化的碳反应能够更容易地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二氧化碳地表通量模型将有助于确定是否可以使用大气测量来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，并通过使用基金会的智力优势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.