PARENT SESSION
Poster Session # 15: Plant Ecology.
Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Specific leaf area and dry matter content estimate leaf thickness in laminar leaves.
Vile, Denis*,1, 2, Shipley, Bill*,1, Garnier, Eric*,2, 1 Universite de Sherbrooke, Sherbrooke, Quebec, Canada2 Centre d'Ecologie Fonctionnelle et Evolutive, Montpellier, France
ABSTRACT- Leaf thickness is a functional trait related to leaf and plant functioning, and which has an impact on the ecological distribution of species. Thickness is not straightforward to measure however, due both to the diversity of structure among leaves, and to the heterogeneity of the trait within the leaf itself. In laminar leaves, it can be demonstrated that average thickness is the inverse of density × SLA × LDMC; (SLA, specific leaf area = leaf surface area to dry mass ratio; LDMC, leaf dry matter content = leaf dry mass to fresh mass ratio). Assessing that density is constant across species, we tested whether leaf thickness can be estimated from SLA and LDMC which are easier to measure, and included in large scale screening programmes of comparative ecology. This was done at the interspecific level for a total of 1047 data points, using both original and published data sets from widely-differing geographical areas. We fit the following general linear covariance model: log(measured thickness) ∼ dataset + log(1/(SLA × LDMC) + interaction. As predicted by the approximation, T = (SLA × LDMC)-1, there was no significant difference in the intercepts across studies, the overall intercept was not significantly different from zero (indicating a mean leaf density of 1), and the slope associated with log(SLA × LDMC) did not differ significantly from -1. We conclude that a simple estimation of average thickness could be accurately given by the inverse of SLA × LDMC, also called the Hughes constant (K = projected surface / fresh mass). Although these findings suggest that the average leaf density is close to unity, that of individual species varies around this value, which produced some scatter around the relationship. This scatter can therefore be interpreted in relation to the tissue composition of leaves.
Key words: specific leaf area, laminar leaves, leaf thickness, dry matter content