LTREB: Legacy effects of compounding disturbances in the Amazon: implications for ecosystem carbon and water cycling

LTREB：亚马逊复合干扰的遗留影响：对生态系统碳和水循环的影响

• 批准号: 2027827
• 负责人: Paulo Brando
• 金额: $ 59.96万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-15 至 2023-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2027827&HistoricalAwards=false
• 关键词: LTREB; Legacy; effects; compounding; disturbances

The carbon stored in the Amazon’s forests is equivalent to ten years of current global carbon fossil-fuel emissions. This large carbon reservoir has seemingly grown over the past few decades and mitigated some of the negative effects on the global climate system associated with greenhouse gas emissions. At the same time, Amazon forests transfer enough moisture to the atmosphere to influence regional precipitation patterns. Interactions between climate change, deforestation, logging, windstorms, and wildfires have threatened the carbon stocks and climate regulatory functions of Amazon forests. Growing concerns that ongoing climate change combined with human disturbances will change Amazon forests into open savannas across large regions. This long term experiment in environmental biology award focuses on a forest that lies at the edge between continuous neotropical forests and savannas. This is an area where native vegetation has been fragmented and is frequently subject to interactions between human and natural disturbances such as fires, droughts, and windstorms. This award evaluates forest resilience from seasonally dry evergreen tropical forests to multiple disturbances based on long- term ecological measurements of a highly threatened Amazon forest. The project’s outcomes could inform regional land and fire management, particularly the development of new strategies to avoid catastrophic wildfires that reduce the capacity of forests to provide ecosystem services. This award will also connect US-based research with researchers and institutions in Brazil, in the process helping to train a diverse group of US students. Finally, the award represents important benchmarks for land surface models and remote sensing techniques that have been widely used to understand potential trajectories of tropical forests This award tests the hypothesis that forests subjected to novel compounding disturbances use different pathways to recover climate services. Disturbed forests that experience minor, short-term reductions in climate functions such as ET and net carbon uptake, have high forest resilience and low probability of large-scale forest replacement by scrubland. However, repeated disturbances triggering long-term losses of forest climate functions would point to low forest resilience. This award will add a decade of ecological data to a long-term, large-scale experimental site in southeast Amazonia that has been degraded by edge effects, recurrent fires, two windthrow events, and multiple droughts. These extended data measurements will permit a comprehensive assessment of how potential future pathways of the experimentally disturbed forests affect ecosystem-level climatic functions across different successional forest pathways and as plant traits change. The experimental site is located in one of the most threatened regions of the Amazon, on the boundary between a dense evergreen rainforest and seasonally dry forests and where native vegetation has been fragmented and subjected to anthropogenic (fire, edge effects) and natural disturbances (droughts and windthrow events). How forests’ long-term climate functions change as a function of novel disturbances and climate change has direct implications for the future of the world’s largest tropical forest. This award will rely on long-term ecological measurements to build a clearer understanding of Amazon forest resilience to multiple disturbances. It will evaluate how interactions between fire legacies to trees (e.g., wounds to tree trunks) and extreme weather events (droughts, windstorms) affect forest climatic functions. In the next ten years, this award will lead to a new understanding of how forest successional pathways and plant traits influence ecosystem-level ET and carbon stocks following compounding disturbances. This award will provide new insights into the (as yet unquantified) thresholds that may lead to large-scale ecosystem change under future climate and land use changes.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.

亚马逊森林中储存的碳相当于当前全球化石燃料碳排放量的十年。这个巨大的碳库似乎在过去几十年里有所增长，缓解了温室气体排放对全球气候系统的一些负面影响。与此同时，亚马逊森林向大气输送了足够的水分，从而影响了地区的降水模式。气候变化、森林砍伐、伐木、风暴和野火之间的相互作用已经威胁到亚马逊森林的碳储量和气候调节功能。越来越多的人担心，持续的气候变化加上人类的干扰将把亚马逊森林变成大片地区的开阔草原。这一长期环境生物学实验奖的重点是位于连续的新热带森林和稀树草原之间的森林。这是一个本土植被支离破碎的地区，经常受到火灾、干旱和风暴等人类和自然干扰之间的相互作用。该奖项基于对受到高度威胁的亚马逊森林的长期生态测量，评估了从季节性干燥的常绿热带森林到多种干扰的森林弹性。该项目的成果可以为区域土地和火灾管理提供信息，特别是制定新的战略，以避免降低森林提供生态系统服务的能力的灾难性野火。该奖项还将把美国的研究与巴西的研究人员和机构联系起来，在此过程中帮助培养不同的美国学生群体。最后，该奖项代表了广泛用于了解热带森林潜在轨迹的陆地表面模型和遥感技术的重要基准。该奖项检验了一种假设，即受到新的复合干扰的森林使用不同的途径恢复气候服务。受干扰的森林具有轻微的短期减少的气候功能，如ET和净碳吸收，具有较高的森林复原力和被灌木丛大规模取代的可能性较低。然而，反复的干扰会导致森林气候功能的长期丧失，这将表明森林的复原力较低。这一奖项将为亚马逊东南部的一个长期、大规模的试验场增加十年的生态数据，该试验场已经因边缘效应、反复发生的火灾、两次风灾和多次干旱而退化。这些扩展的数据测量将使我们能够全面评估受实验干扰的森林未来的潜在路径如何影响不同演替森林路径上的生态系统级气候功能，以及随着植物特性的变化。试验场位于亚马逊最受威胁的地区之一，在茂密的常绿雨林和季节性干燥森林之间的边界上，当地植被已经支离破碎，受到人为(火灾、边缘效应)和自然干扰(干旱和风灾)的影响。森林的长期气候功能如何随着新的干扰和气候变化而变化，对世界上最大的热带森林的未来有着直接的影响。该奖项将依靠长期的生态测量，以建立对亚马逊森林对多种干扰的适应能力的更清晰的理解。它将评估火灾对树木造成的影响(例如对树干的伤害)和极端天气事件(干旱、风暴)之间的相互作用如何影响森林气候功能。在接下来的十年里，这一奖项将使人们对森林演替路径和植物特性如何在复合干扰后影响生态系统水平的ET和碳储量有一个新的理解。这一奖项将为未来气候和土地利用变化下可能导致大规模生态系统变化的门槛(尚未量化)提供新的见解。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。