Interspecific variation in leaf litter production, decomposition, and nitrogen and phosphorus loss from decomposing leaves in a humid subtropical forest ecosystem of northeastern India

Studies providing direct experimental evidence of species impact on litter dynamics in forest ecosystems are limited. The decomposition processes in subtropical forests are also poorly understood. We studied variation in quality and quantity of leaf litter production, decomposition, and N and P loss from decomposing foliar litter in three tree species as well as a mixed-species plot in a subtropical broad-leaved forest of northeastern India. The annual leaf litter production was highest in Rhododendron arboreum Sm. (7293 kg·ha–1·year–1) followed by Myrica esculenta Buch.-Ham. ex D. Don (6902 kg·ha–1·year–1), mixed plots (6808 kg·ha–1·year–1), and Neolitsea cassia (L.) Kosterm (6299 kg·ha–1·year–1). The annual N and P inputs through litter were highest in the mixed plot (N, 111.0 kg·ha–1·year–1; P, 4.8 kg·ha–1·year–1) and lowest in the Rhododendron plot (N, 65.6 kg·ha–1·year–1; P, 2.9 kg·ha–1·year–1). The highest decay rate was recorded for Neolitsea (k = 0.89) and lowest for Myrica (k = 0.53) litter. The rate of N loss was highest for Neolitsea (k(N) = 1.39) and lowest for Myrica (k(N) = 0.68) species, and P loss was in the order of mixed (k(P) = 1.02) > Neolitsea (k(P) = 0.88) > Rhododendron(k(P) = 0.84) > Myrica (k(P) = 0.62). Acid-insoluble residue, which indicates lignin content and P-related litter chemistry, were correlated with the differential decomposition rates and nutrient loss pattern among the species.