Studies On Soil Fertility Of Different Vegetation Community Types In Shelter Forest In The Upper Reaches Of The Yangtze River In Northern Sichuan

It was analyzed comprehensively that indies of soil physical properties, soil chemistry properties and soil enzyme activities in the Different Vegetation Community Types in Shelter Forest in the upper reaches of the Yangtze River in northern Sichuan,were measured by standard plot sampling and normal lab analysis. The influences of planting C.funebris on the soil fertility are also discussio.The results obtained are as follows:The plantation of C.funebris would improve soil physical properties, the experiment results incidented that along with the C.funehri grow, capillary water-holding capacity, supreme water-holding capacity, total porosity,capillary porosity and non-capillary porosity is gradually improving, although the change in the field capacity still not obvious, it shows a general trend of decline. The growth of the C. funebris produce a certain negative effect on the soil chemistry properties. As the growth of cypress fores, the content of soil n, p, k, organic matter showed the trend of shock downward as a cosine function. The cosine cycle and the regenerate cycle of the C. funebris forest has a certain degree of consistency,it indicated that soil chemistry properties would rise at a stage,as the change of the community structure and still can't attain the level before the plantation of C. funebris,as the growth of the C. funebris forest, the maximum of the soil chemistry properties at a stage would be decreased. Cluster analysis showed soil chemical properties ofindividually depth(0-20cm,20-40c)vary at forty-years-old C. funebris plantation.The plantation of C. funebris restrained soil enzyme activities which gradually declined with the growth of C. funebris. The results of integrated evaluation of soil nutrient fertility showed that soil fertility expressed a trend of shock downward as a cosine function with the growth of C. funebris,so the plantation of C.funehri reduced the soil comprehensive quality.The results of integrated evaluation of soil nutrient fertility among 5 community-types showed that Cupressus funebris pure forest(0.4241)is highest,and then,Pinus x Cupressus>Quercus> theropencedrymion,the lowest soil fertility is Pinus massoniana pure forest(0.1666).And the orders with the growing season of theropencedrymion is.autumn> spring>summer,and the others is spring> autumn> summer, summer, the total trend showed spring> autumn> summer.The soil nutrient fertility in the 0-20cm layer is more than what in the 20-40cm layer.1 The results of integrated evaluation of soil nutrient fertility among 7 community-types showed that the most soil fertility mark is Cunninghamia Lanceolata(0.4676),,and then Phyllostachys bambusoides>Neosinocalamus affinis>Liquidambar formosana> theropencedrymion>shrub,the lowest is Phyllostachys heterocycla (0.2560).And the orders with the growing season of Phyllostachys heterocycla and theropencedrymion is summer>autumn> spring,and the others is spring> autumn> summer.,the total trend showed spring> autumn> summer.The soil nutrient fertility in the 0-20cm layer is more than what in the 20-40cm layer.