Changing gears during succession: shifting functional strategies in young tropical secondary forests

Background

Adaptations toresource availability strongly shape patterns of community composition along successional gradients in environmental conditions. This study examines the extent to which variation in functional composition explains shifts in trait-based functional strategies in young tropical secondary forests during the most dynamic stage of succession (0–20 years).

Research Goals & methods

The study examines forest composition in secondary forest plots along a chronosequence in the Agua Salud Project, Panama. Functional composition of two size classes in 51 secondary forest plots was determined using community-weighted means of seven functional traits, which were intensively measured on 55 woody plant species (n = 875–1,761 individuals).

Conclusions & takeaways

Along the successional gradient in forest structure, there was a significant and consistent shift in functional strategies from resource acquisition to resource conservation. Leaf toughness and adult plant size increased significantly with age class, while net photosynthetic capacity decreased significantly during succession. Shifts in functional strategies within size classes for photosynthetic capacity and wood density also support the hypothesis that changes in functional composition are shaped by environmental conditions along successional gradients. ‘Hard’ traits such as photosynthetic capacity and leaf toughness exhibited greater sensitivity to successional changes in forest structure than ‘soft’ traits such as leaf mass area and leaf dry matter content.