Leaf litter decomposition and nutrient mineralization patterns in regrowing stands of a humid subtropical forest after tree cutting

Decomposition dynamics, and N and P mineralization patterns of leaf Litter of Pinus kesiya, Quercus dealbata, Q. griffithii, Rhododendron arboreurn and Schima khasiana were studied in forest of three different ages in a humid subtropical region of India. The decay pattern varied from species to species. The decay pattern, characterized using a composite linear regression equations, exhibited two to three distinct phases during leaf litter decomposition. Initial lignin, nitrogen (N) and lignin/N showed significant negative correlations with decay rate, whereas soil properties like pH, moisture and total Kjeldahl nitrogen (TKN) and climatic variables, e.g. rainfall and air temperature, showed positive correlations. The annual dry matter decay constants (k) varied from 0.77 in R. arboreum to 1.39 in Q. griffithii. Nutrient release from the decomposing litter was influenced by the seasonal cycle of mineralization and immobilization processes. Net mineralization was rapid during rainy season, as nitrogen (N) and phosphorus (P) concentrations in the decomposing leaf litter decreased by ca. 20-50% from the preceding season, while immobilization occurred during winter when nutrient concentration increased up to 60%. Annual dry matter decay, net N and P mineralization constants for Q. dealbata were higher in the 16-year old regrowth than in the 13-year old regrowth. (C) 1998 Elsevier Science B.V.