Collaborative Research: The other side of tropical forest drought: Do shallow water table regions of Amazonia act as large-scale hydrological refugia from drought?

合作研究：热带森林干旱的另一面：亚马逊流域的浅水位区域是否可以作为干旱的大型水文避难所？

• 批准号: 1949894
• 负责人: Scott Saleska
• 金额: $ 28.86万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1949894&HistoricalAwards=false
• 关键词: Collaborative; Research; other; side; tropical

The vegetation that covers the Earth has many important functions. One of the biggest impacts of vegetation is trapping and storing carbon dioxide from the atmosphere. The vast Amazon rainforest makes a significant contribution to this carbon storage function. However, the Amazon forest is being threatened by recent changes to climate, which is making droughts stronger and more frequent. A big question is whether the Amazon will be resilient to these droughts, or whether they will slow forest growth and kill trees, which would release carbon. A significant challenge is the lack of information about a large portion of the Amazon forest—about 30%—with shallow water tables, where trees live in an environment of excess water. In these water-logged forests, tree growth is slow because soil conditions are poor for tree roots. Here, drought could actually be beneficial to trees by reducing this water-logging. On the other hand, these forests have roots that grow close to the soil surface and require wet conditions. In this case, strong droughts that last a long time dry the upper soil and could reduce growth more, killing more trees than in forests with well-drained soils. This project will answer questions about the role of belowground water sources as an important control on response of tropical forest to drought. Data about forest growth and carbon dioxide exchange will be made available to the broader research community. This project will also help train students in how to measure forests, and provide information about tropical forests to the public.This project will measure forest canopy response to drought at sites in the Brazilian Amazon. The approach is to unify field ecology with remote observation of ecosystems from canopy towers and satellites. Canopy towers constructed in this project—representing the first of their kind in water-logged soils of the interior Amazon—provide detailed information about tree growth. The capacity of the forest canopy for photosynthesis will be measured as well as leaf demography and phenology. This new knowledge will be combined with networks of existing canopy towers in deep water table depth sites, satellite images spanning the Amazon, data on tree growth and death from a network of forest surveys, and detailed measurements of soil water and other environmental factors. This project will build an accurate new understanding of the factors that impact forest carbon cycling, while contrasting water-logged with well-drained soil responses. A data-based model of ecosystem structure and function will offer a quantitative accounting of the contribution of these water-logged forests in the Amazon to climate change responses. These results have the potential to transform our current perspective on drought effects in tropical forests.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.

覆盖地球的植被具有许多重要的功能。植被的最大影响之一是从大气中捕获和储存二氧化碳。广阔的亚马逊雨林为这种碳存储功能做出了重大贡献。但是，亚马逊森林正受到最近气候变化的威胁，这种变化使干旱更加强大，更频繁。一个大问题是，亚马逊是否会韧性地弹性，或者它们是否会减慢森林生长并杀死树木，这将释放碳。一个重大的挑战是缺乏有关亚马逊森林的大部分地区（约30％）的信息，而浅水桌子，树木生活在多余的水环境中。在这些水上的森林中，树木的生长很慢，因为土壤条的土壤条件较差。在这里，干旱实际上可以通过减少这种水上的水分对树木有益。另一方面，这些森林的根部生长在靠近土壤表面并需要湿条件。在这种情况下，持续很长时间的强烈干旱会使上层土壤干燥，并可以减少更多的生长，而杀死树木比排水良好的森林多。该项目将回答有关地下水源的作用的问题，这是对热带森林对干旱反应的重要控制。有关森林增长和二氧化碳交换的数据将提供给更广泛的研究社区。该项目还将帮助培训学生如何测量森林，并向公众提供有关热带森林的信息。该项目将衡量巴西亚马逊场地对干旱的森林树冠反应。该方法是通过对树冠塔和卫星的生态系统的远程观察来统一现场生态。该项目中建造的树冠塔（在亚马逊内部水上土壤中代表了第一个类型的塔楼）提供了有关树木生长的详细信息。将测量森林冠层光合作用的能力以及叶子人口统计学和物候。这些新知识将与深水桌深度站点中现有顶篷塔的网络相结合，跨越亚马逊的卫星图像，有关森林调查网络的树木生长和死亡的数据以及土壤水和其他环境因素的详细测量。该项目将对影响森林碳循环的因素有一个准确的新理解，同时将水与排水良好的土壤反应形成对比。基于数据的生态系统结构和功能模型将对亚马逊中这些水上森林对气候变化反应的贡献进行定量计算。这些结果有可能改变我们当前对热带森林中干旱影响的看法。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响标准，被认为值得通过评估来支持。

项目成果

Asymmetric response of Amazon forest water and energy fluxes to wet and dry hydrological extremes reveals onset of a local drought‐induced tipping point

• DOI: 10.1111/gcb.16933
• 发表时间: 2023-09
• 期刊: Global Change Biology
• 影响因子: 11.6
• 作者: N. Restrepo-Coupe;Bradley O'Donnell Christoffersen;Marcos Longo;Luciana F. Alves;K. S. Campos;Alessandro C da Araujo;R. D. de Oliveira;N. Prohaska;R. da Silva;Raphael Tapajós;K. Wiedemann;S. Wofsy;S. Saleska

Diverse anthropogenic disturbances shift Amazon forests along a structural spectrum

各种人为干扰使亚马逊森林发生结构变化

• DOI: 10.1002/fee.2590
• 发表时间: 2023
• 期刊: Frontiers in Ecology and the Environment
• 影响因子: 10.3
• 作者: Smith, Marielle N;Stark, Scott C;Taylor, Tyeen C;Schietti, Juliana;de Almeida, Danilo Roberti;Aragón, Susan;Torralvo, Kelly;Lima, Albertina P;de Oliveira, Gabriel;de Assis, Rafael Leandro
• 通讯作者: de Assis, Rafael Leandro

Reframing tropical savannization: linking changes in canopy structure to energy balance alterations that impact climate

• DOI: 10.1002/ecs2.3231
• 发表时间: 2020-09
• 期刊: Ecosphere
• 影响因子: 2.7
• 作者: S. Stark;D. Breshears;S. Aragón;J. C. Villegas;D. Law;Marielle N. Smith;D. Minor;R. Assis;D. R. Almeida;G. Oliveira;S. Saleska;A. Swann;J. Moura;J. Camargo;R. Silva;L. Aragão;R. Oliveira