Specific leaf area (SLA) serves as a proxy to predict total carbon content in understory individuals of the neotropical canopy palm Socratea exorrhiza

Abstract

Evaluating intraspecifc and ontogenetic variation in SLA is critical to understand how functional traits infuence plant ftness and regeneration strategies. SLA is usually expressed as an average value per species. Its variation across ontogenetic stages and environmental gradients is poorly known, particularly in palms. I measured SLA in 112 palms of Socratea exorrhiza in the understory of a tropical rainforest in Costa Rica. Total carbon content sequestered per palm (kg) was estimated from an allometric equation. I determined the regression between Ln SLA and Ln carbon content, and then used principal components to summarize the regeneration strategy of S. exorrhiza by examining the allometry of stem length and diameter, number of fronds, number of stilt roots, stilt root cone height, slenderness ratio, SLA, and carbon content. SLA predicted total sequestered carbon (slope = −4.33, r 2=0. 52). Smaller values of SLA were associated with increased carbon content and larger palms. Two components explained 77% of the variation in functional traits. The frst (76%) was dominated by stem diameter, height, stilt root cone, and carbon content (negatively associated with SLA) and refected palm size; the second (15%) was dominated by slenderness ratio and number of leaves and refected allocation to growth in height. The inverse relationship between SLA and sequestered carbon is consistent with the initial shade tolerant, conservative resource use strategy of S. exorrhiza.