Nutrient changes and release during decomposition of leaf litter in Himalayan oak-conifer forest

Abstract

Changes in nitrogen, calcium, water-soluble compounds, and total available carbohydrate in decomposing leaf litter of six tree and one shrub species, enclosed in nylon net bags and placed in a mixed oak conifer forest, were examined for a period of 487 days. The concentration of nitrogen increased during decomposition in all litter species. This increase was up to threefold in Aesculus indica, Quercus floribunda, and Quercus leucotrichophora. In most species the absolute increase in nitrogen mass was observed when decomposition had progressed up to 213 days. However, in Daphne cannabina and Ilex dipyrena, the absolute mass of nitrogen was never greater than the initial mass at any stage of decomposition. The absolute mass of calcium in litter bags generally declined with time. The concentration of water-soluble compounds and of total available carbohydrates varied from species to species; both these constituents, however, continually decreased with the progress of decomposition. Within 1 year, the release of nitrogen, water-soluble compounds, and total available carbohydrates was 100% in D. cannabina, A. indica, and I. dipyrena. In Cedrus deodara, Q. floribunda, and Q. leucotrichophora about 50% of total nitrogen input to the forest floor as litter fall was released by decomposition. In Cupressus torulosa only 14% of nitrogen falling as leaf litter was released during a period of 1 year.