Data from: The intraspecific variation of functional traits modulates drought resilience of European beech and pubescent oak

A higher frequency and intensity of droughts will impair forest
productivity. Therefore, improving our understanding of which factors
enhance tree growth resilience against drought has become a crucial issue,
but we lack information at the intraspecific level. In this study, we
investigate the role played by climatic conditions and tree
characteristics in the growth response to severe droughts in two deciduous
Fagaceae species near their southern distribution limit: the temperate
European beech (Fagus sylvatica) and the Mediterranean pubescent oak
(Quercus pubescens). The study area is located in Catalonia, NE Spain,
where 149 trees were cored covering the water availability gradient of the
species in the region. In addition, tree size (diameter and height) and an
ensemble of stem, leaf and hydraulic traits were collected for each tree.
Growth responses to extreme droughts during the period 1980-2015 were
assessed using resilience indicators based on residual basal area
increment series predicted by a model including growing-season water
balance. Although resistance was unrelated to drought intensity, higher
water availability improved recovery and reduced drought legacy effects.
Taller trees showed higher resilience against drought, which could be
explained by the relationship between the variation in tree height and
functional traits, such as leaf nitrogen concentration, leaf turgor loss
point and resistance to xylem embolism. For both species, trees with lower
cavitation resistance, higher leaf nitrogen concentration and tighter
stomatal regulation (suggested by less negative turgor loss point and
carbon isotope composition) displayed better performance during and after
severe droughts. Both species showed a progressive decrease in resilience
and increase of legacy effects. Synthesis. This study highlights the
relevance of analyzing intraspecific variation of functional traits
involved in tree water and carbon balance to improve our understanding of
the resilience and variability of growth responses to drought within
species.