Physical And Chemical Properties And Ecological Effects Of Soil In The Process Of Vegetation Restoration In The Loess Plateau

Based on vegetation restoration located at hilly-gully region of the Loess Plateau, soil physical and chemical properties and ecological effects of the different artificial vegetation restoration patterns which located at Zhifanggou Watershed in the hilly-gully region of the Loess Plateau were studied by using field survey, experimental analysis and the principal component analysis. The research results the interaction between vegetation restoration and soil properties changes. It provides the scientific basis for the evaluation of the ecological and vegetation restoration effects. The main research results were summarized as follows:(1) With the years of vegetation restoration, soil nutrient content increased. And the disparities which compare with the farmland reduced along with the soil layer depth's increasing. Soil organic matter content increased in 0-20cm, 20-40cm and 40-60cm depth. The changes of soil total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium content were not as large as soil organic matter content. And in some levels, the contents were lower than farmland. The different cover types also have the different influences to soil nutrient. Arbor had the best soil amelioration effect, bush and herbage were next.(2) The changes of soil bulk density and water content were not obvious with the years of vegetation restoration. But they were affected obviously with different cover types. The content change in soil mantle had 3 peaks of soil aggregate and 1 peak of soil micro-aggregate. Arbor soil aggregate contents were more than bushes'and herbages'on each peak.(3) With the years of vegetation restoration, soil catalase activity increased in 20-40cm and 40-60cm depth and it increased largely in 0-20cm depth. Soil urease activity decreased in 0-20cm depth and it increased in 20-40cm and 40-60cm depth. Soil sucrase activity increased in 0-20cm, 20-40cm and 40-60cm depth. Soil phosphatase activity increased in 0-20cm depth and it increased largely in 20-40cm and 40-60cm depth. The different cover types also have the different influences to soil enzyme. Arbor had the best soil amelioration effect, bush and herbage were next. (4) With the years of vegetation restoration, plant height, DBH (diameter at breast height) and coverage increased. Accompanying species appeared in the process of vegetation restoration. And the amount of species increased with the years of vegetation restoration, too. S.viridis and A.sacrorum appeared in many sample plot. They were common species in this watershed.(5) By applying principal component analysis, P.tabulaeformis was the first in synthesis alexa. After that were R.pseudoacacia (30y), R.pseudoacacia(25y), R.pseudoacacia(12y), M.pumila, C.Korshinskii, G.Merr, A.adsurgens, wasteland(25y), wasteland(30y) and wasteland(12y). In the same year of vegetation restoration, arbor had the better soil amelioration effect than bush and herbage. In the same cover type, the effect increased with the years of vegetation restoration. The effects of different years of vegetation restoration were better than the effects of different cover types.