DOI: 10.5061/dryad.nm3d3
title: Data from: The roots of the drought: hydrology and water uptake strategies mediate forest-wide demographic response to precipitation

description: 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 relative depths at which 12 common species in the forest
 accessed water via a model of water-stress. Finally, we tested whether our
 estimates of species relative uptake depths predicted mortality in
 multi-year drought. The hydrological model revealed clear belowground
 niches as precipitation was decoupled from water availability by depth at
 multi-annual scale. Species partitioned the hydrological niche by
 diverging in their uptake depths and so in the same forest stand,
 different species experienced very different drought patterns, resulting
 in clear differences in species-specific growth. Finally, species relative
 water uptake depths predicted species mortality patterns after the
 multi-year drought. Species that our method ranked as relying on deeper
 water were the ones that had suffered from greater mortality, as the zone
 from which they access water took longer to recharge after depletion. This
 research changes our understanding of how hydrological niches operate for
 trees with a trade-off between realized growth potential and survival
 under drought with decadal scale return time. The eco-hydrological
 framework highlights the importance of species-specific below ground
 strategies in predicting forest response to drought. Applying this
 framework more broadly may help us better understand species-coexistence
 in diverse forest communities and improve mechanistic predictions of
 forests productivity and compositional change under future climate.
description: tree_species_growth_time_seriesThis file contains growth dynamics for 12 common tree species by size class over 20 years (4-yr time step) in the 50 ha Mudumalai Forest Dynamics Plot.tree_species_abundance_time_seriesThis file contains 20-yr long (1988-2008) annual abundance dynamics for 12 common tree species (&gt;= 5 cm DBH) in the 50 ha Mudumalai Forest Dynamics Plot (MFDP).tree_species_mortality_time_seriesThis file contains 20-yr long (1988-2008) annual mortality dynamics for 12 common tree species (&gt;=5 cm DBH) in the 50 ha Mudumalai Forest Dynamics Plot.tree_species_infoThis file provides taxonomic information corresponding to the codes used in the other files for the 12 common species.tree_species_taxonomic_info.txtKargudi_daily_rainfallThis file contains 24 yr long (1990-2013) daily rainfall record at Kargudi weather station, 4 km away from the 50 ha Mudumalai Forest Dynamics Plot.