Comprehensive evaluation of soil quality fertility in Jiulong Mountain,Beijing

Based on soil data of 13 forest types in Jiulong Mountain,Beijing,6 soil indicators were firstly selected,and then their membership values were calculated by non-linear membership functions,their weight coefficients were determined by grey association analysis method. Soil quality of different stands in Jiulong Mountain,Beijing was finally evaluated through integrated soil fertility indices model and additive fertility quality indices model. Results showed as follows:( 1) p H was generally low and the soil nutrient contents were disproportional in the tested area. Meanwhile,there was great difference of soil nutrient contents not only among forest types but also between the upper soil layer and other soil layers in the same stand,and the soil nutrient contents reduced gradually from the upper to lower soil layers.( 2) Available phosphorus and total nitrogen were the key factors to affect the soil quality in the tested area.( 3) The organic matter and alkali hydrolysable nitrogen had larger proportion in the weight coefficients.( 4) The trends of soil quality calculated by two models were consistent. The top two of soil comprehensive quality were the shrubbery and Fraxinus chinensis forest in all soil layers,whereas the lowest quality was the Pinus sylvestris var. mongolica forest,and the soil comprehensive quality of the upper soil layer was far higher than other soil layers in all forest types. So the soil comprehensive quality was low and was mostly in the middle and lower levels,only the top soil quality was better. And this research can provide reference for the further forest tending and soil sustainable utilization in Jiulong Mountain,Beijing.