Consistency of species ranking based on functional leaf traits

Specific leaf area (leaf area to dry mass ratio), leaf dry matter content (leaf dry mass to saturated fresh mass ratio) and leaf nitrogen concentration (LNC) have been proposed as indicators of plant resource use in data bases of plant functional traits. We tested whether species ranking based on these traits was repeatable by studying spatio-temporal variations in specific leaf area and leaf dry matter content of water-saturated leaves (SLA(SAT) and LDMCSAT), as well as in LNC, for 57 herbaceous and woody species (or subsets thereof) growing under the Mediterranean climate of southern France. Interseason and intersite variations were more pronounced than interannual variations, but species ranking for a given trait remained mostly consistent in space and time. Classifications based on LDMCSAT were generally more repeatable across years and sites, whereas those based on SLASAT were more stable over seasons. LNC usually gave the least repeatable classifications. Species rankings were not completely similar for the three traits. Discussion of reproducibility, ease of trait measurement, as well as trait-function relationships led us to propose that measurements of the leaf traits, SLA(SAT) and/or LDMCSAT, were the most suitable in large screening programmes.