Water supply following drought: Effects on drougt legacy and resilience in a tropical forest - A case study in Xishuangbanna, China

Abstract

Climate change has made it essential to understand the effects of drought on carbon dynamics in tropical forest ecosystems. However, research on the postdrought (PD) period is relatively limited, particularly with regard to the resilience of the carbon cycle affected by available water. To determine the effects of water availability during PD on resilience and legacy effects in tropical forests, we used a spatially explicit individual-based dynamic global vegetation model (SEIB-DGVM) to simulate gross primary productivity (GPP) to proxy the process. We established multiple water supply scenarios based on ecological water demands and regional climatic standard precipitation through the composite of gradients in quantity and duration to characterize variations in environmental water availability after droughts end. Under different PD water supply patterns, the degree of GPP resilience and its legacy effects varied significantly. Specifically, ecosystem resilience to drought was positively correlated with the percentage of PD water supply and negatively correlated with the duration until water conditions returned to normal, while the negative legacy effect of drought on GPP exhibited the opposite relationship. After a drought, a rapid high-level water supply promoted stronger GPP resiliency and moderated the drought legacy effects. Although legacy effects varied with water supply patterns, the negative legacy effect on GPP appeared only in the first year after drought. Observing biomass changes in roots, leaves, woody plants, and herbaceous plants after droughts, it is clear that tropical forest ecosystems can adjust their carbon allocation strategies in response to differences in water availability. To more accurately predict the fate of tropical forests in response to climate change, it is necessary to assess the impact of PD environmental climate condition changes on their dynamic resilience processes.