Amazon forest biogeography predicts resilience and vulnerability to drought

• 成果类型: Article
• 署名作者: Chen, Shuli; Stark, Scott C.; Nobre, Antonio Donato; Cuartas, Luz Adriana; de Jesus Amore, Diogo; Restrepo-Coupe, Natalia; Smith, Marielle N.; Chitra-Tarak, Rutuja; Ko, Hongseok; Nelson, Bruce W.; Saleska, Scott R.
• 署名单位: University of Arizona; Michigan State University; Instituto Nacional de Pesquisas Espaciais (INPE); Bangor University; United States Department of Energy (DOE); Los Alamos National Laboratory; Institute Nacional de Pesquisas da Amazonia; University of Arizona
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5158
• DOI: 10.1038/s41586-024-07568-w
• 发表日期: 2024-07-04
• 关键词: atmospheric infrared sounder; ecological resilience; vegetation indexes; Causal Inference; linking plant; modis evi; mortality; climate; biomass; soil

摘要

Amazonia contains the most extensive tropical forests on Earth, but Amazon carbon sinks of atmospheric CO2 are declining, as deforestation and climate-change-associated droughts1-4 threaten to push these forests past a tipping point towards collapse5-8. Forests exhibit complex drought responses, indicating both resilience (photosynthetic greening) and vulnerability (browning and tree mortality), that are difficult to explain by climate variation alone9-17. Here we combine remotely sensed photosynthetic indices with ground-measured tree demography to identify mechanisms underlying drought resilience/vulnerability in different intact forest ecotopes18,19 (defined by water-table depth, soil fertility and texture, and vegetation characteristics). In higher-fertility southern Amazonia, drought response was structured by water-table depth, with resilient greening in shallow-water-table forests (where greater water availability heightened response to excess sunlight), contrasting with vulnerability (browning and excess tree mortality) over deeper water tables. Notably, the resilience of shallow-water-table forest weakened as drought lengthened. By contrast, lower-fertility northern Amazonia, with slower-growing but hardier trees (or, alternatively, tall forests, with deep-rooted water access), supported more-drought-resilient forests independent of water-table depth. This functional biogeography of drought response provides a framework for conservation decisions and improved predictions of heterogeneous forest responses to future climate changes, warning that Amazonia's most productive forests are also at greatest risk, and that longer/more frequent droughts are undermining multiple ecohydrological strategies and capacities for Amazon forest resilience. Drought response is structured by water-table depth in higher-fertility Southern Amazonia, whereas lower-fertility Northern Amazonia supports more-drought-resilient forests independent of water-table depth.