DOI: 10.5061/dryad.1jwstqjwn
title: Phytogeographic origin determines Tropical Montane Cloud Forest hydraulic trait composition

description: Tropical montane cloud forests (TMCF) have unique climatic conditions,
 which allow the coexistence of plant lineages with different
 phytogeographic origins from tropical versus temperate climates. Future
 climate projections suggest TMCFs will be subjected to increasing drought
 stress due to fog uplift and higher temperatures, possibly leading to tree
 mortality and local extinctions, and consequently changes in forest
 composition and functioning. Characterising community functional
 composition, trade-offs among traits and the drivers of community assembly
 is of utmost importance to improve our capacity to predict the response of
 montane plant communities to forecast climate change. Here, we aimed to
 test if species from different phytogeographic origins (i.e. tropical -
 evergreen x deciduous - and temperate) differ in drought vulnerability and
 how the co-existence of these groups change the hydraulic composition of
 TMCF`s. We used a framework based on measurements of key hydraulic traits
 (i.e. xylem embolism resistance, hydraulic safety margin, stomata control,
 turgor loss point, minimum water potential) of 16 dominant species
 (&gt; 70% of the forest basal area) within a TMCF in the Atlantic Rain
 Forest Domain in southeast Brazil. We used community-weighted means to
 model whether removing each species group would change the community
 hydraulic functional composition. Temperate, tropical deciduous and
 tropical evergreen groups differ in their hydraulic functioning and these
 differences explain forest functional composition and taxa dominance.
 Temperate and tropical deciduous taxa were consistently more vulnerable
 hydraulically (i.e. lower safety margins and embolism resistance). The
 coexistence of different phytogeographic lineages is a key determinant of
 TMCF hydraulic composition. We also used models including phylogeny to
 evaluate the variation of hydraulic traits across Phytogeographic groups,
 and the results suggest some niche conservatism associated with plant
 hydraulic functioning. Our results provide evidence of the importance of
 species phytogeographic origin on TMCF functioning, and niche conservatism
 in the evolution of hydraulic traits. The higher drought vulnerability
 observed in temperate group might be a mechanistic explanation for the
 expansion of temperate taxa distribution to wetter places during past
 colder and drier climate. Thus, we suggest hydraulic functional traits may
 be useful to predict future dynamics of TMCFs under changing climatic
 conditions.
description: A full description about the data sampling is in the manuscript
 related to this data. 
description: In the uploaded files there is a README file with the metadata
 that helps to understand each column.  The only NAs are
 for the vulnerability curves data (P50, P88 and slope.vc) for Psychotria
 vellosiana, as it was not possible to have a curve for this species. See
 the paper for more details. The species Ilex
 taubertiana was also not included in some group analysis as it was
 classified as cosmopolitan.