Leaf Litter Decomposition and Associated Nutrient Release Dynamics Under Varying Temperature and Precipitation in a South Asian Tropical Forest

Abstract

Litter decomposition plays a vital role in nutrient cycling and maintaining ecosystem functionality, particularly in forested landscapes. However, the decomposition dynamics of common tropical timber species remain underexplored in many regions, including Bangladesh. This study investigated the leaf litter decomposition and associated nutrient (nitrogen, phosphorus, potassium) release patterns of five widely planted timber species, Chukrasia tabularis, Dipterocarpus turbinatus, Hopea odorata, Tectona grandis, and Swietenia macrophylla on the Chittagong University campus. Using the litter bag method, decomposition rates were measured across both dry and wet seasons to assess seasonal variability and environmental influences. The results revealed that Chukrasia tabularis exhibited the highest mass loss (33% in the dry season and 60% in the wet season), followed by Hopea odorata (38% and 55%), while Tectona grandis showed the lowest decomposition rates (23% and 25%). Decomposition was most rapid in Hopea odorata during the dry season (0.57 g/month) and Dipterocarpus turbinatus in the wet season (0.89 g/month). In the wet season, decomposition rates were significantly (p < 0.05) correlated with temperature and precipitation across all species. In contrast, during the dry season, only Tectona grandis and Hopea odorata showed significant correlations with temperature, while only Chukrasia tabularis and Hopea odorata were significantly influenced by precipitation. Nutrient release patterns varied by species and nutrient type: nitrogen release was highest in Chukrasia tabularis (26.89 mg/g), phosphorus in Hopea odorata (16.53 mg/g), and potassium in Dipterocarpus turbinatus (53.53 mg/g), whereas Swietenia macrophylla consistently showed the lowest nutrient release rates. These findings highlight species-specific and seasonal variations in litter decomposition and nutrient dynamics, offering insights for forest management, species selection, and ecosystem nutrient budgeting in tropical forest plantations.