Specific leaf area: A predictive model using dried samples

Specific leaf area (SLA; fresh-leaf area/dry mass) describes the amount of leaf area for light capture per unit of biomass invested. The standard protocol is simple; however, it requires recently collected sun-exposed leaves to determine fresh-leaf area, limiting where and which samples can be studied. A protocol to predict SLA for fresh leaves from herbarium-dried leaves was developed from samples collected in a dry forest in Bolivia. Leaf area was measured both fresh and dried on the same leaf samples to generate two general mixed-effects models, varying in their inclusion of the position in the crown where the leaf developed. As a test of the potential generality of the models for other systems, we applied them to samples collected in an oak-hickory forest in Missouri, USA. Both models performed well. A recommended protocol for studies predicting SLA from dry leaves was developed. These predictive models and protocols can extend the temporal, geographic, ecological and taxonomic scope of SLA studies.