Modeling drought mortality and resilience of savannas and forests in tropical Asia

Abstract

The projected increase of drought occurrence in many tropical and sub-tropical regions globally under future climates will affect terrestrial ecosystems, particularly by increasing drought-induced plant mortality. The capacity to simulate drought mortality in vegetation models is therefore essential to understand future ecosystem dynamics. Using the trait-based vegetation model aDGVM2, we assessed drought mortality and resilience in tropical Asia under climate change. We conducted model simulations for ten sites in tropical Asia, representing a biogeographic gradient. Responses of vegetation attributes and mortality rates were simulated until 2099 for hypothetical drought scenarios and recovery times were calculated. Model simulations showed biomass dieback during drought due to increased plant mortality, primarily among tall and old trees. Drought responses were related to hydraulic traits and associated ecological strategies. Despite severe drought impacts, recovery was possible, but recovery times differed between ecosystem attributes. We conclude that the aDGVM2 enhances our ability to understand drought impacts in tropical ecosystems. The model can simulate increased mortality during drought in a trait- and individual-based modeling framework. It indicated drought resilience of forests and adaptation to drought by changes in community trait composition and the demographic structure. Yet, further model improvements are required to better represent drought impact and recovery.