Pattern of Litterfall Production Throughout a Tropical Humid Forest Chronosequence

Abstract

Neotropical landscapes are often characterized as mosaics of actively grazed pastures and forest fragments at various stages of succession. Restoring abandoned pastures requires intervening with actions informed by local ecological succession. Here we evaluate how litter production, a key component of nutrient cycling in forests, varies between physiographic landscapes (hill and lowland mountain), among stand age groups (early-secondary: 0–20 year, intermediate-secondary: 20–40 year, and old-growth forests: > 40 year), and in response to climatic (precipitation and irradiation) and forest structure and biodiversity variables (stand density, basal area, species density, diversity), in a tropical humid forest chronosequence. Total and leaf litter production was higher in the lower elevation hill landscape. Leaf litter production increased with stand age in both landscapes but only correlated positively with forest structure and biodiversity in the hill landscape. Lack of correlation in the mountain landscape is attributed to greater variance in structure and species composition in the subset of plots selected from this landscape for this study. Both landscapes exhibited an asynchronous, bimodal regime of leaf fall in response to precipitation. Leaf litter peaks prior to the wet season likely occur in response to water stress, while peaks after the wet season that coincided with increasing solar irradiation are likely the result of a leaf turnover strategy to optimize photosynthesis. Ecological succession in these landscapes does not appear limited in leaf litter production, but further research on the drivers of leaf litter production recovery is necessary to adequately guide intervention efforts.