Between-tree variations in leaf ? 13 C of Quercus pubescens and Quercus ilex among Mediterranean habitats with different water availability

Abstract

In this study, sun leaf carbon isotope composition (δC) of two co-occurring woody Mediterranean species (Quercus pubescens Willd., a deciduous oak, and Q. ilex L., an evergreen one) was investigated on four sites with different water availability. The total range of δC values was 4.4 and 3.1‰ for Q. pubescens and Q. ilex respectively. The intra-site variability was about 3‰. Total mean per species was equal. There were significant differences among sites, but at each site means of δC were not significantly different between species. A simple physiological model predicts no difference in intrinsic water-use efficiency (WUE) between evergreen and deciduous oaks. The relationship between site means of δC and water parameters suggests that there is a leaf functional adjustment with respect to available water resource. No correlation was found between δC and the contents of any mass-based biochemical constituent. Nevertheless there was a significant correlation between δC and leaf mass per area of Q. ilex. For both species, there is also a positive correlation between leaf δC and individual crown area, i.e. a structural characteristic at tree level. Causal relations between δC and plant-environment interactions are discussed.

Productivity, carbon isotope discrimination and leaf traits of trees of Eucalyptus globulus Labill. in relation to water availability

“…Many other studies have found positive correlations for woody species between D and indices of water availability such as rainfall, transpiration, soil water potential, predawn leaf water potential and soil water availability, and negative correlations between D and either potential evaporation or global solar radiation (Leavitt & Long 1991;McNulty & Swank 1995;Stewart et al 1995;Damesin, Rambal & Joffre 1997;Walcroft et al 1997;Schulze et al 1998;Korol et al 1999;Anderson et al 2000;Miller et al 2001;Barbour et al 2002). However, our study is one of few to have also quantified productivity, leaf traits and their relation to D in a similar genotype across a large gradient of water availability.…”

Retrieving leaf conductances from sap flows in a mixed Mediterranean woodland: a scaling exercise

“…For pubescens [14]. These ranges are much greater than those normally found within natural ecosystems, but are less than those recorded by Mooney et al [45] and Kohom et al [39].…”

Gender, light and water effects in carbon isotope discrimination, and growth rates in the dioecious tree Ilex aquifolium

“…Thus greater leaf nitrogen contents would bring about comparatively larger stomatal conductances, with increased intercellular CO 2 concentrations and leaf carbon isotope discrimination. Other studies, such as that of Damesin, Rambal & Joffre (1997), found no correlation between leaf ∆ 13 C and the massbased nitrogen content in leaves of two oak species occurring in sites with different water availability.…”