Study On Hydrological Effects And Evaluation Of Different Vegetation In Western Sichuan, China

The hydrological effects of litter layers and soil,physical and soil nutrient property of soil,and diversity in the different vegetation types were carried out in the sub-alpine region of western Sichuan.The main conclusions are as following:1) The cumulated mass(CM) of litter layers increased with increased age of plantation and natural secondary series,and in the order of primitive fir forest＞70a spruce plantation forests＞70a fir secondery forests＞40a spruce plantation forests＞40a conifer mixed forests55a spruce plantation forests＞40a larch plantation forests＞birch forests＞25a conifer mixed forests＞30a fir secondery forests＞shrub forests＞locust plantation forests,farm land,bare land;and maximal water holding capacity(MWHC) of litter layers had similar trend,and in the order of primitive fir forest＞70a spruce plantation forests＞70a fir secondery forests＞40a spruce plantation forests＞40a conifer mixed forests55a spruce plantation forests＞25a conifer mixed forests＞30a fir secondery forests＞40a larch plantation forests＞birch forests＞shrub forests＞locust plantation forests,farm land,bare land.2) The soil bulk density and porosity are different obviously among each vegetation types.The soil bulk density increased with the increment of soil depth,porosity reduce obviously on the contrary.3) In the layer of 0～30 cm of each vegetation type,the soil non-capillary water-storage capacity were 270.3～736.3t/hm²,the highest one is 30a fir secondary forest;Maximum water-storage capacity were 1126.9～2315.4,the highest one is shrub forest.4) The result of correlation on soil physical property showed that:There are some correlations among the soil bulk density,non-capillary porosity,capillary porosity,total porosity,non-capillary water-storage capacity,and Maximum water-storage capacity.5) Soil infiltration rate were different obviously among the plots.The process of soil infiltration accords with the Kostiakov model:(?)=ax^-b.Bulk density and non-capillary porosity are the main factors which effect the soil infiltration greatly by analyzing the relationship between the infiltration rate and main physical;Soil bulk density, non-capillary porosity,capillary porosity total porosity,CM,MWHC had an significant influence on soil solid infiltration rate.6) Soil organic matter,total N,hydrolytic N,rapidly available K,total P,available P reduce obviously with depth of the soil in each plot,but total K value increase obviously on the contrary.Soil nutrient indices had significant differences among each plot,but not significant in the soil layer.The result of correlation on soil nutrient indices showed that: There were some correlations among the pH,soil organic matter,total N,hydrolytic N, rapidly available K,total K,total P and available P.7) Several diversity indices were selected for use,which were the Margalef index,Simpson index,Shannon-Wiener index and Pielou index.The result showed that:The species diversity of plantations increased with their age,but decreased in the natural secondary series.8) According to the result of comprehensive evaluation on ecological function score,in the order of primitive fir forest＞70a spruce plantation forests＞70a fir secondery forests＞shrub forests＞40a conifer mixed forests＞55a spruce plantation forests＞birch forests＞30a fir secondery forests＞40a larch plantation forests＞40a spruce plantation forests＞25a conifer mixed forests＞farm land＞bare land＞locust plantation forests.