A standardized protocol for the determination of specific leaf area and leaf dry matter content

1. The impact of sample preparation, rehydration procedure and time of collection on the determination of specific leaf area (SLA, the ratio of leaf area to leaf dry mass) and leaf dry matter content (LDMC, the ratio of leaf dry mass to fresh mass) of mature leaves was studied in three wild species growing in the field, chosen for their contrasting SLA and LDMC. 2. Complete rehydration was achieved 6 h after samples were placed into water, but neither of the procedures tested-preparation of samples before rehydration or temperature applied during rehydration-had a significant effect on the final values of SLA or LDMC. 3. As expected, water-saturated leaves had a lower LDMC than non-rehydrated leaves; more surprisingly, their SLA was also higher. The impact of rehydration on SLA was especially important when the SLA of the species was high. 4. There was no significant effect of time of sampling on either trait in any species over the time period covered (09.00-16.30 h). 5. These results suggest that SLA and LDMC obtained on water-saturated leaves (SLA(SAT) and LDMCSAT) can be used for species comparisons. We propose a standardized protocol for the measurement of these traits. This would allow for better consistency in data collection, a prerequisite for the constitution of large databases of functional traits.