Litter Decomposition in a Lowland Rain Forest and a Deforested Area in Sri Lanka

Abstract

A comparative study of litter decomposition in a tropical lowland rain forest and an adjacent fernland using leaf litter from a dominant forest tree species, Cullenia ceylanica (Bombacaceae), and frond litter of the most abundant fernland species, Dicranopteris linearis (Gleicheniaceae), revealed significant differences in percentage mass lost between the two litter types and between the two sites: C. ceylanica leaf litter was reduced by 63 percent in one year in the forest vs 41.7 percent in the fernland, whereas D. linearis frond litter was reduced by 24.6 percent during the same period in the forest vs 15.7 percent in the fernland. A positive correlation with the amount of rainfall was observed for the mass loss of C. ceylanica litter in both sites; litter of D. linearis showed no such correlation with rainfall. Nutrient changes examined over one year indicated immobilization of nitrogen in both litter types in both sites and that of phosphorus only in D. linearis. Concentration and mass of K, Mg, and Ca decreased with decomposition in all four experimental treatments. A relatively slow rate of decomposition and an accumulation of organic matter in the fernland contribute to the conservation of nutrients in this aggrading ecosystem.