| The study expounded the degraded characteristics of hillside fields as a kind of degraded ecosystem from landscape ecology and restoration ecology, furthermore probed into the characteristics of vegetation restoration and its effects on soil. The results indicate:First, hillside fields always come along with the forest landscape degradation. Hillside fields ecosystems are products of extremely degraded forest ecosystem, and they themselves are seriously degraded ecosystems. The degraded characteristics mainly are forest landscape fragmentation, landscape pattern degradation, ecosystem structure oversimplification, ecosystem functions decline, soil degradation, productivity dropping and biodiversity decreasing, and so on.Second, vegetation communities developed from simply to complicatedly after converting hillside fields to forest. Simultaneously degraded forest landscapes are restored and improved by certain degrees. Biodiversity of communities drastically increased, and the dominant populations are perennial herbs. Pathway of vegetation succession approximately is from annual herbs to shrubs (they are breedings of cultivar) plus perennial herbs to trees plus shrubs and herbs, finally to natural mixed forests. In the process, both capacities of soil and water conservation and productivities of ecosystems will be enhanced.Third, effects of vegetation restoration on soil mainly are as following:(1) Change of volume weight is based on both soil properties and models of vegetational restoration in short-term (about 3 years). It may rise, reduce or approximately unchange. In long period (about more than 15 years), volume weight may increase or decrease, which depends on richness of ground vegetation and litter in stands. Namely it will decrease if there is plenty of ground vegetation and litter in stand, otherwise it will increase.(2) Remarkable changes happended to soil porosities and moisture contents, which were complicated both by defferent soil textures and vegetation retoration models. In short-term, water and soil conservation benefit of lithosols is greatly strengthened with improvement of total porosity, capillary porosity, and saturated water retaining cpacity, capillary moisture capacity, and field moisture capacity. However, the changes of loam and clay soil are just the contrary of lithosols except capillary porosity replaced by noncapillary porosity. Total porosity always enlarges; noncapillary porosity may increase or decrease in long period, which depend on ground vegetation. Namely it will increase provided plenty of ground vegetation, if not will decrease. Saturated water retaining capacity and field capacity will approximate to, even overtake the level of ploughs after a period. So capability of the waterand soil conservation will strengthen in long period.(3) In early days of converting hillside fields to forest, soil organic substance increased, while available nitrogen, phosphate and potassium had remarkablely decreased. With vegetations restoring, available nitrogen could rapidly recover, but available phosphate and potassium could only recover little by little after a long period of decreased process. The total soil nutrient slightly decreased, but its tendency was not definite.(4) Cease of tillage and restored vegetations are the most important contributors to effectivelyt cut down run-off and soil erosion, because soil itself was negative for water and soil conservation at beginning of cease tillage on hillside fileds. However the capacity of soil and water conservation of soil itself could be gradually strengthened with vegetations restoring. Therefore vegetaion, litter and soil all play important roles in conservating water and soil.Fourth, the several main vegetation restoration models such as public welfare forest, non-timber product forest, bamboo forest, industrial material forest plantation and tree plus forage grass, which have been developed in large scale in Sichuan province, can effectively restore forest landscape, cut down run-off and soil erosion, imp...
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