DOI: 10.5061/dryad.sf7m0cgg9
title: Vulnerability segmentation is vital to hydraulic strategy of tropical‒subtropical woody plants

description: The vulnerability segmentation hypothesis proposes that the hydraulic
 function of expensive stems can be protected by sacrificing cheap leaves,
 which has been proven to be a key strategy to survive drought for woody
 species from arid regions. Climate change has caused increasing severe
 droughts in relatively humid tropical-subtropical forests. However,
 whether vulnerability segmentation (measured as the differences in
 embolism resistance between stem and leaf; P50leaf‒stem) plays a role in
 the hydraulic strategy of tropical-subtropical woody plants remains
 unclear. We investigated 12 key hydraulically-related traits of stems and
 leaves (i.e., cavitation resistance, water potential, safety margin,
 vulnerability segmentation, leaf-sapwood area ratio, and water use
 efficiency) and mortality rates for 130 dominant woody species from six
 forest types with a range of aridity index in tropical‒subtropical China.
 Our main objectives were to: 1) build a stem-leaf hydraulic framework and
 capture the key hydraulic traits; 2) compare the hydraulic strategies of
 different forest types and functional groups; and 3) elucidate the
 influence of environmental factors and hydraulic traits on mortality rate.
 Trait network analysis revealed close relationships among stem and leaf
 hydraulic traits, where cavitation resistance, turgor loss point,
 and P50leaf‒stem were the key traits. In general, a
 larger P50leaf‒stem was associated with lower minimum water
 potential, leaf hydraulic safety margin, and leaf-sapwood area
 ratio but higher wood density, stem hydraulic safety margin, and water use
 efficiency. Tropical
 forest (high aridity) had higher leaf
 embolism resistance, P50leaf‒stem, wood density and water use
 efficiency than subtropical
 forest (low aridity), while
 shrubs showed higher leaf embolism resistance and more
 negative turgor loss point than trees. However,
 stem-leaf hydraulic strategy did not differ significantly between
 evergreens and deciduous. Both aridity index and hydraulic traits affect
 species mortality. Particularly, P50leaf‒stem was a good
 predictor of drought-induced mortality in tropical forests. Synthesis: Our
 results recommend that vulnerability segmentation should be incorporated
 into the hydraulic strategy of tropical‒subtropical woody plants to
 explore their drought response to future climate change.
description: # Vulnerability segmentation is vital to hydraulic strategy of
 tropical‒subtropical woody plants
 [https://doi.org/10.5061/dryad.sf7m0cgg9](https://doi.org/10.5061/dryad.sf7m0cgg9) ## Description of the data and file structure Table 1: Definitions and ecological significance of 13 traits measured in this study. Table 2: List of the 130 species with details of each site, forest type, family, growth form, and leaf habits in tropical‒subtropical forest. Abbreviations of sites and forest type are given in Table 1. Basal area: cm2 ha-1; Individuals number: no ha-1; Mortality number (total; DBH: &lt;5cm; DBH:5~15cm; DBH:&gt;15cm): no ha-1; *C*leaf indicates leaf capacitance (mmol m-2 MPa-1). There is a lack of basal area and mortality data for some species distributed in tropical karst forests (TKF) at PX, tropical seasonal rainforest (TRF) and tropical mangroves forest (TMF).“—” indicates missing values. Table 3: List of the 130 species with all hydraulic traits and mortality rate. Trait abbreviations and functional meanings are provided in Table 1.“—” indicates missing values.