The roots of the drought: hydrology and water uptake strategies mediate forest-wide demographic response to precipitation

Drought-induced tree mortality is expected to increase globally due to climate change, with profound implications for forest composition, function and global climate feedbacks. How drought is experienced by different species is thought to depend fundamentally on where they access water vertically below ground, but this remains untracked so far due to the difficulty of measuring water availability at depths at which plants access water (few to several tens of meters), the broad temporal scales at which droughts at those depths unfold (seasonal to decadal), and the difficulty in linking these patterns to forest-wide species-specific demographic responses. We address this problem through a new eco-hydrological framework: we used a hydrological model to estimate belowground water availability by depth over a period of two decades that included a multi-year drought. Given this water availability scenario and 20yr long-records of species-specific growth patterns, we inversely estimated the re...