DOI: 10.5061/dryad.sv1v1
title: Data from: Inbreeding and neighbouring vegetation drive drought-induced die-off within juniper populations

description: Drought-induced episodes of forest die-off are being reported world-wide,
 and recent evidence shows that increases in temperature due to climate
 change are contributing to this decline. Several ecological mechanisms
 have been invoked at the plant level to explain the vulnerability of trees
 to this widespread drought-induced mortality. Apart from ecological
 factors, some genetic factors might also influence population responses to
 disturbances: it has been reported, for example, that genetic diversity
 enhances population resilience through genotypic complementarity, whereas
 genetic relatedness between conspecific individuals exerts a negative
 influence on variations in fecundity. However, we lack empirical data that
 prove any functional relationship between levels of individual inbreeding
 or kinship and patterns of drought-induced forest die-off resulting from
 field conditions. Here, we investigated the role of ecological, phenotypic
 and genetic factors in determining the response of trees to prolonged
 drought conditions. We focused on populations of the small tree Juniperus
 phoenicea L. that recently experienced severe drought-induced die-off in
 semi-arid woodlands from central Spain. We correlated mean individual
 inbreeding (f) and mean kinship between individuals within a plot (fij)
 with remaining green plant canopy and crop size. We found that f was
 negatively correlated with plant performance, whereas fij was not.
 Healthier canopy also tended to correspond with large plants and
 neighbourhoods dominated by trees and shrubs, suggesting a role for
 facilitative interactions and microsite heterogeneity. Accordingly, the
 probability of severe damage increased linearly with f, and individuals
 growing in open habitats with f values &gt; 0·625 only had 15% chance
 of remaining unaffected after a period of prolonged drought. We show that
 both vegetative and reproductive responses to prolonged drought episodes
 are determined by multiple factors, including individual inbreeding.
 Therefore, any fuller understanding of phenomena such as drought-induced
 forest die-off needs to incorporate the contribution of individual genetic
 variations in conjunction with plant–plant interactions.
description: Lloret_Garcia_2016_Functional_EcologyN: number of tree ID: identity of each tree PLOT: plot where the individual was sample Lat: Latitude Lon: Longitude BA: total basal area (BA) at ground surface, measured individually for each stem and then totalled dieback: green.canopy: fruits: herbs: % of herbs in the neighbouring vegetation shrubs: % of shrubs in the neighbouring vegetation trees: % of tree species in the neighbouring vegetation eco.pca1: ecological variables were summarised by two Principal Component Axis. These are the scores retained from PCA1. eco.pca2: ecological variables were summarised by two Principal Component Axis. These are the scores retained from PCA2. f: mean individual inbreeding estimated based on Jombart et al. (2008) fij: mean relatedness of each tree with all other trees within its plot. This is the Loiselle's inbreeding estimator according to Loiselle et al. (1995)