Fine root decomposition and nitrogen mineralisation patterns in Quercus leucotrichophora and Pinus roxburghii forests in central Himalaya

Decomposition of three root litter classes of Quercus leucotrichophora and Pinus roxburghii was studied during 18 months to examine the temporal chang e in nutrient concentration and mass loss and its spatial pattern and to de velop a Vegetational model of litter mass loss based on the controls of cli mate and substrate quality. The experiments involved two forest sites in an altitude of 1600 and 2160 m for Quercus and Pine, respectively. in additio n a standard root litter was placed on the forest floor of each of the fore st site. Litter with greater root diameter tended to be lower in nutrient c oncentration. Pattern of change of nitrogen concentration differed with dia meter. Monthly mean temperature, rainfall and humidity could account for 54 -56% of monthly mass loss for both forest sites. Ash free mass loss of fine roots decreased with increasing root diameter. The rate of decomposition w as significantly correlated with initial nutrient concentration. Material w ith higher C/N ratios had a longer duration of immobilisation and in turn a slower release phase. (C) 2000 Elsevier Science B.V. All rights reserved.