| China is one of the most serious soil erosion in world. Guizhou is the most typical and concentrated distribution area with karst landforms in China. Because of the especial geological background, there are some differences from other regions for the soil erosion character. So it possesses the very important significance to reinforce the research on soil erosion character in karst mountain area. In the spatial viewpoints of the upper, middle and lower reaches, the plateau regions and gorge regions, the paper chooses five typical karst small catchments as the studied areas to analyse the spatial difference about the characters of soil erosion factor and the spatial changes about the soil quality characters in the process of karst rocky desertification in ecological mamagment area.Paper is to study the systematic, correlation and arrangement of soil erosion factors by the SPSS software and to study and system analysis the inter-space change rule of soil erosion character and soil quality character, during rocky desertification base on different grades rocky desertification of soil erosion mounts and erosion factors. In different space basic cell of different grades rocky desertification sample locations by drain plot. The physical and chemical characteristic, zoology environment factors, correlation analysis, linearity analyses, inter-space contrast analyze etc. Research result indicate:(1) Soil erosion character have marked difference of all research area: In plateau area of Guizhou,the middle reaches of Wujiang drainage′s soil erosion degree is more weak than the upper reaches,the lower reaches of Wujiang drainage and gorge area. To study discover that the soil erosion modulus is lower than other area. Its'soil erosion degree is more graveness because its'anti-erodibility fixed mount of year and soil ply is lower than other area. The middle reaches'soil erosion degree is most gently for the vegetation cover degree high and vegetation defend earth action strong. (2) To study discover the clay content and saturated permeability ascend when the slop is above 25°and the soil erosion mounts is downtrend or change is not too. So I think that the critical slope is about 25°of soil erosion in gorge area. In altiplano area landform is flatness and the steep sloping field is only distributing peak forest back fall. The transition of between gradual slope and abrupt slope is the most serious area of soil erosion, which soil erosion depth every year is 0.38(mm/a). Soil erosion depth every year is 0.16(mm/a) at above 25°abrupt slope area which soil erosion degree is quite feebleness. So the critical slope is about 25°of soil erosion in altiplano area too.(3) To study discover that the slope, vegetation coating degree and soil erosion mounts have distinct relativity and through linearity regression analysis constitute model equation: 0～15°Ms=48.359e-0.402C′, r=0.557, s=0.194; Through the model equation discover when the slope is steadiness that the soil erosion modulus is reduces current with the vegetation coating degree increase. The abrupt slope in altiplano area is scrubs which have prominence action to reduce the soil erosion. The gradual slope is main farming fields, its vegetation is cropper, which vegetation coating degree is lowness and protect earth ground is ebb for agriculture production.(4) The >0.05mm sand grain content proportion is less in gorge area and the <0.001mm clay content proportion is highness which cost is about 35%. Study indicated that soil viscidity is graveness. The <0.01mm physicals clay, silt and pack running off amount is litter. The >0.05mm sand grain content proportion is high and the clay content proportion is less in the altiplano area which indicated its'soil erosion degree is lowness and soil clayey is not graveness. The soil total porosity proportions are all high and the non-capillary porosity proportion is lowness which is go against to water infiltration in the two study areas. The saturation rate of permeation of topsoil is double times of the subsoil. The subsoil have greatly prominence impact on the surface runoff for the soil layer is flimsiness which cause surface runoff form is earlier, duration time is longer and make soil erosion happen frequency is more. The soil water stable structural failure frank is 30% of gorge area and is 15% of altiplano area, which indicated that the soil anti-erodibility of altiplano area are more strong than gorge area.(5) Though study the upper reaches of Wujiang drainage discover that between slope and soil erosion mete have the notability correlation (a=0.05) which correlation coefficient r=0.799. It indicated the slop is higher and the soil erosion mete is more. Take linearity trend analyze for the soil erosion depth of the different glebe utilize of different slope in the lower reaches of Wujiang drainage know that the critical slope is about 25°. The >0.05mm sand grain content are 20.45%,32.56%,24.69% of the upriver, middle reaches and lower reaches of Wujiang drainage. <0.001mm clay grain content is 24.9%, 25.11%,22.37%. Through analysis this mechanism compose know that they are discrepancy is very little and the middle reaches's soil erosion degree is most ebb. Though research the soil porosity indicated the total porosity content is 50% that is discrepancy not too of all Wujiang drainage. The non-capillary porosity content is very little which is go against rain infiltration of upper drainage and lower drainage. The soil porosity combination of middle drainage is more favor to surface water infiltration and reduce surface runoff to depress soil erosion amounts. The soil saturation permeation rate indicated that the soil saturation permeation rate of upper drainage is most but the soil saturation permeation rate is diversity prominence between the topsoil and subsoil. The ratio between topsoil and subsoil of Wujiang drainage is 2.73 of upper reaches, 1.66 of middle reaches, 3.17 of lower reaches. The soil saturation permeation rate of upper reaches and lower reaches is most go against surface water infiltration. The soil water stable structural failure frank is 20.13% of upper drainage, 16.62% of middle drainage, 19.50% of lower drainage which indicated soil reunite is most ebb and the soil anti-erodibility is feebleness. It is concluded that the soil erosion critical grade is about 25 degree in karst areas of Guizhou province. (6) The vegetation coverage is lower of upper drainage of Wujiang. Though study the upper reaches of Wujiang drainage discover that among slope, soil erosion mete and vegetation coverage have the notability correlation (a=0.05) which correlation coefficient r=0.779, 0.853; Vegetation defend earth action coefficient is 0.67 of the forest for water and soil conversation of the middle reaches. The C cost of slope infield is 0.25. The average C cost is 0.4137. Take linearity regression analyze to constitute model equation for soil erosion depth of every year and the vegetation coverage degree: 0～15°: Ms=0.602-0.010/C′; r=0.784, s=0.011; 15～25°: Ms=0.755-0.002/C′, r=0.992, s=0.004;>25°: Ms=0.495-0.006/C,r=0.867, s=0.086;The equation indicated that vegetation coverage is higher the soil erosion depth of every year is litter(7) The soil quality change disciplinarian during of rocky desertification: the >0.05mm sand grain content change current is the native ground sample plot>intensity rocky desertification>gently rocky desertification>moderate rocky desertification>latent rocky desertification; <0.001mm clay grain content change current is latent rocky desertification>gently rocky desertification > moderate rocky desertification> intensity rocky desertification >the native ground sample plot; The >0.05mm sand grain content is little indicated that soil erosion is graveness and the sand grain is take away many; The <0.001mm clay content more indicated that the soil viscidity is serious during soil erosion degenerate process; The soil total porosity change trend is the native ground sample plot>latent rocky desertification> intensity rocky desertification> gently rocky desertification> moderate rocky desertification; The non-capillary porosity content change trend is the native ground sample plot > intensity rocky desertification> latent rocky desertification >gently rocky desertification> moderate rocky desertification; The >0.25mm water stable structural failure frank change trend is the native ground sample plot intensity rocky desertification> gently rocky desertification> latent rocky desertification> moderate rocky desertification. The nutrition element content is far lower than every grades of rocky desertification that indicated it is soil degraded process during the rocky desertification.
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