Data from: Leaf carbon and oxygen isotopes are coordinated with the leaf economics spectrum in Mediterranean rangeland species

The leaf economics spectrum (LES) describes covariation of traits relevant
to carbon and nutrient economics across plant species, but much less is
known about the relationship between the LES and leaf water economy. We
propose an approach combining the measurement of two leaf traits related
to water use economy, leaf carbon (δ13C) and oxygen (δ18O) isotopic
composition, and the measurement of leaf morphological and nutrient traits
to investigate the link between leaf carbon and nutrient economics and
water use. We tested the relationships between leaf traits linked to
carbon and nutrient use within the LES and water use traits using leaf
δ18O as a proxy of stomatal conductance (gs) and δ13C as a proxy of
intrinsic water use efficiency (WUEi) across 15 Mediterranean rangeland
species grown in an irrigated common garden and in a natural grassland in
Southern France. The target species spanned a wide range of variation in
leaf morphological and nutrient trait values and a wide range of leaf δ18O
and δ13C values. PCA analysis revealed multiple associations among leaf
morphology, nutrients and isotopic composition, with the first axis alone
explaining 56.0% of the total variation across species. Leaf δ18O and δ13C
covaried with leaf morphology and leaf nutrient concentrations along a
single resource use axis. Species with high leaf δ18O and δ13C (low gs and
high WUEi) exhibited a resource-conservative strategy (high LDMC, low leaf
N, P and K) whereas species with low leaf δ18O and δ13C (high gs and low
WUEi) showed a more resource-acquisitive strategy (high SLA and leaf N, P
and K). These leaf trait syndromes and resource use strategies were
strongly conserved across sites with contrasting environmental conditions,
indicating that foliar δ18O and δ13C can be included as an integral part
of the LES for this set of rangeland species. Overall, the data suggest a
tight coupling and coordination between water, carbon and nutrient use
strategies across herbaceous plant species. A dual δ18O and δ13C isotope
approach combined with LES trait measurements is a promising tool to more
comprehensively assess the diversity of resource use strategies among
coexisting plant species.