Premium
Isotopes reveal contrasting water use strategies among coexisting plant species in a Mediterranean ecosystem
Author(s) -
MorenoGutiérrez Cristina,
Dawson Todd E.,
Nicolás Emilio,
Querejeta José Ignacio
Publication year - 2012
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2012.04276.x
Subject(s) - water use efficiency , interspecific competition , stomatal conductance , biology , stable isotope ratio , mediterranean climate , δ13c , ecology , ecological niche , isotopes of carbon , ecosystem , botany , photosynthesis , total organic carbon , habitat , physics , quantum mechanics
Summary Variation in the stable carbon and oxygen isotope composition (δ 13 C, Δ 18 O) of co‐occurring plant species may reflect the functional diversity of water use strategies present in natural plant communities. We investigated the patterns of water use among 10 coexisting plant species representing diverse taxonomic groups and life forms in semiarid southeast Spain by measuring their leaf δ 13 C and Δ 18 O, the oxygen isotope ratio of stem water and leaf gas exchange rates. Across species, Δ 18 O was tightly negatively correlated with stomatal conductance ( g s ), whereas δ 13 C was positively correlated with intrinsic water use efficiency ( WUE i ). Broad interspecific variation in Δ 18 O, δ 13 C and WUE i was largely determined by differences in g s , as indicated by a strong positive correlation between leaf δ 13 C and Δ 18 O across species The 10 co‐occurring species segregated along a continuous ecophysiological gradient defined by their leaf δ 13 C and Δ 18 O, thus revealing a wide spectrum of stomatal regulation intensity and contrasting water use strategies ranging from ‘profligate/opportunistic’ (high g s , low WUE i ) to ‘conservative’ (low g s , high WUE i ). Coexisting species maintained their relative isotopic rankings in 2 yr with contrasting rainfall, suggesting the existence of species‐specific ‘isotopic niches’ that reflect ecophysiological niche segregation in dryland plant communities.