Database Of Functional Traits Research Articles

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

Summary 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. 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. 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. 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). These results suggest that SLA and LDMC obtained on water‐saturated leaves (SLASAT 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.

Accurate description of the abundance of taxa and their biological traits in stream invertebrate communities: effects of taxonomic and spatial resolution.

Studies of biodiversity and ecosystem function require to consider the identification level that accurately describes the functional diversity of communities, in terms of their biological traits, at different spatial scales. Therefore, we combined three published data sets of stream macroinvertebrate abundances collected at three spatial scales with a database of functional species traits (e.g. life history, morphology, physiology, and behaviour). We investigated the abundance of taxa and their traits at five levels of taxonomic (from species to class) and three levels of spatial resolution (from local habitat to catchment). We used multivariate analyses and correlations to evaluate the accuracy of community descriptions through the stability of such descriptions, the degree of similarity of site ordinations, and the overall community structure expressed at each taxonomic level. The accuracy of community descriptions based on the abundance of taxa depended on the spatial scale considered. The accurate description of the abundance of taxa required identifications to genera and/or families on the local habitat scale, while species identifications were needed on the catchment scale. In contrast, the accurate description of the abundance of biological traits was achieved by identifications to species, genera, or families on all three spatial scales. Thus, species identifications may not be necessary for future studies on the functional diversity of the stream benthos at different spatial scales.