The impacts of elevated CO 2 on forest growth, mortality, and recovery in the Amazon rainforest

作者：Yitong Yao, Philippe Ciais, Émilie Joetzjer, Wei Li, Lei Zhu, Yujie Wang, Christian Frankenberg, Nicolas Viovy · 发表于：Earth System Dynamics · 年份：2024 · DOI：10.5194/esd-15-763-2024 · 被引用次数：13 · 研究领域：Plant Water Relations and Carbon Dynamics、Plant responses to elevated CO2、Forest ecology and management

Abstract. The Amazon rainforest plays a crucial role in global carbon storage, but a minor destabilization of these forests could result in considerable carbon loss. Among the external factors affecting vegetation, elevated CO2 (eCO2) levels have long been anticipated to have positive impacts on vegetation, including the direct enhancement of both photosynthesis and productivity and increasing water use efficiency. However, the overall impact of eCO2 on the net carbon balance, especially concerning tree-mortality-induced carbon loss and recovery following extreme drought events, has remained elusive. Here, we use a process-based model that couples physiological CO2 effects with demography and both drought mortality and resistance processes. The model was previously calibrated to reproduce observed drought responses of Amazon forest sites. The model results, based on factorial simulations with and without eCO2, reveal that eCO2 enhances forest growth and promotes competition between trees, leading to more natural self-thinning of forest stands. This occurs following a growth–mortality trade-off response, although the growth outweighs the tree loss. Additionally, eCO2 provides water-saving benefits, reducing the risk of tree mortality during drought episodes. However, extra carbon losses could still occur due to an eCO2-induced increase in background biomass density, leading to “more carbon available to lose” when severe droughts happen. Furthermore, we found that eCO2 accelera...