| China is one of the most severe countries of soil and water loss in the world.The second remote sensing investigation of soil and water loss indicated that Chinese area of soil and water loss readied 356km~2,accounted for 37.08 percent of whole country.The soil and water loss results in the problems of ecological depravation,soil degeneration,mud and sand imperilment,etc,threatens severely development of Chinese economy and society,and has become Chinese number one environmental problem.For the sake of speeding up the progress of soil and water loss treatment,improving ecological environment and effective and reasonable utilizing soil resource,Water Conservancy Department brought forward a new plan of soil and water loss treatment in 2001:the natural self-rehabilitation forces promote vegetational restoration, accelerates the soil and water loss treatment and improves the ecological environment,namely ecological rehabilitation.There were 128 counties(towns) puting in practice the ecological rehabilitation experimental unit project of soil and water conservertion in the whole country in 2002.Dayao County was one of 7 counties of the experimental unit of Yunan province.For understanding and grasping the rules and effects of project and measures of Dayao's cological rehabilitation improving soil and controling erosion, inspecting stations were estabilished in the representatiive typical place of the rehabilitation area and inspecting contents and index that can scientifically reflect the changing trends of the effect of improving soil and controling erosion were also done in terms of the inspecting technological standards of soil and water conservertion and actual circumatances of the rehabilitation area.We had inspected and studyed the effects of Dayao's ecological rehabilitation project improving soil and controling erosion two years with the traditional inspectability techonology and "3S" inspectability techonology. We had brought forward perfect advice to the exiperimental unit project of Dayao ecological rehabilitation on the inspectability ,analysys and estimatation base.Through the three-year ecological rehabilitation project practice there was a new evidence that the ecological environment qualities had gradually become better. The overlay ratio of the ecological rehabilitation area had increased from 49.40% to 80.44% and the biological diversity of its had increased. The Area of arbor-shrub-grass or shrub-grass community pattern had gradually increased.The sight of the ecological rehabilitation area had been improved,and a majority of the sparse brushwood or bareland hadbecome the green mountain land.The succession of vegetable communities were becoming all right. Through two-year irispectability and reseach,as follows conclusion:(1) Physical and chemical property of soil had been gradually improved and property of anti-erosion and anti-scourability had been gradually enhanced.Indicate by the inspectability : On the "bareland-grass-brush-woodland" land type series,organic matter,>0.25mm water-stable aggregates,soil porosity,soil water content, soil penetration rate and water-stable index had gradually increased moreover bulk denesity,specific grayity,ratio of structure damage and soil anti-scourability modulus reduced.Functions of vegetable improving soil were gradually boosted up and ability of soil resisting erosion was also gradually enhanced(2) Soil erosion of land types that adopted measures of the ecological rehabilitation was obviously controlled. Erosion modulus was""232 ~ 456t/km2.a,and the erosion grade declined to light grade or lower gxade,basically controlled soil erosion.However the bareland,average erosion modulus was 7292.75t/km2.a, was a important source place of soil erosion and a important object of ecological rehabilitation.On the "bareland-grass-brush-woodland" land type series there was a trend of me ranoff and soil erosion gradually weakened and the abilities of vegetable adjusting runoff and controlling erosion were gradually boosted up.Dynamic analysis indicated:Soil erosion of the ecological rehabilitation area had beei* controlled, the faint erosion area added and the light ,middle,st?Dng erosion area discreaed,and the quantities of soil erosion reduced from 194231.09t to 107819.62t,lessened 44.89%.The faint erosion area increased from 182.85km2 to 324.56km2 and the average modulus of soil erosion declined from 1125.73t/km2.a to 344.09t/km2.a. See from a angle of controling soil erosion, effects of the ecological rehabilitation excelled those of other ways,and furthermore, ecological rehabilitation project is fit for brought into effect in the areas of the light and middle erosion and its effects of controling erosion will be the most remarkable.(3) Indicate by the inspectability:There were the very strong relativities between vegetation and soil , runoff and erosion.Furthermore the more complicated were the structures of vegetational community and the more high were the rank of succession,the more strong were the relativities.(4) The "arbor-shrab-grass" or "strrcrb-grass" ^rattero was a better ecological rehabilitation pattern, had better abilities of improving soil,adjusting runoff and controlling erosion.However the function that the grass or "arbor-shrub" pattern conservered water and soil was inferior to the former. Otherwise the least rainfall intension(producing soil erosion) of theformer was higher that of the latter.The ecological rehabilitation measure of slope land changing mesa rehabilitative of wide table-board,anti-slope and a low bank of earth between fields had more notable effects on adjusting runoff and controlling erosion,vice versa.Dayao's ecological rehabilitation practice had come out that the slope land changing mesa of the >3m table-broad,anti-slope and the 20cm low bank of earth between fields was not produced runoff and erosion.(5) On the "bareland-grass-brush-woodland" sucession series,there were the trends : The runoff changed from high to low,erosion from strong to weak, the least rainfall intension from low to high and physical and chemical property of soil had been gradually improved.In terms of analytic method of "time substituted space ",if the vegetation can naturally develop ,early vegetational types of succession will be substituted by terminal vegetational types of succession.There will be more strong abilities of vegetation improving soil and controling erosion and more remarkable effects of those. |
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