Effect of Different Forests on the Soil Quality of Typical Sections on the Western Mauntainous Margins of the Sichuan Basin

In this paper according to the feature of soil profile,mechanical composition,value of pH,nutrient content,a comparatire analysis was made of the soil quality of five forest stand types including Cryptomeria fortunei forest,Cunninghamia Lanceolata forest birch forest,bamboo forest and natural evergreen broad-leaved forest.The results showed that the bamboo forest soil was at a low level in all the above indicators.The coniferous forest soil(Cryptomeria fortunei,Cunninghamia lanceolata) showed well-developed and ripening characteristics;the contents of aggregate structure organic matter and N,P,K in the soil of these two forests were also second only to those in the soil of natural evergreen broad-leaved forest.The eluvial characteristic of nutrients in the surface soil was obvious,and the capacity of the water erosion resistance was very poor.The exchange capacity and saturation degree of their base were as follows:young birch forestnatural evergreen broad-leaved forest bamboo forest Cunninghamia Lanceolata forstCryptomeria fortunei forest.In conclusion,the exchange capacity and saturation degree could accelerate the losing of base ions and cause the acidification of soil.So the crucial technology for maintaining the soil quality are the rational vegetation composition and vegetation management patterns.