| Soil erosion is one of the ecological environment problems in the earth.The continuance of Soil erosion will result in not only the decent of soil quality,but also silt of river & lakes,and flood disaster as well.The water erosion is the main soil erosion.In the recent years,in the process of the exploitation of west region,the human activities are frequent.The trend of soil erosion will be worsen.Therefore,it is the urgent need of soil losses accurately,quickly and dynamically,how to predict & inspect soil losses,and provide scientific base for the repair of soil erosion and implement of soil and water conservation planning.Otherwise,the survey method of soil losses is lagger in Yunnan.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) putting in practice the ecological rehabilitation experimental unit project of soil and water conservertion in the whole country in 2002.Dayao Country was one of 7 countries of the experimentalunit of Yunnan province.For understanding and grasping the rules and effects of project and measures of Dayao's ecological rehabilitation improving soil and controlling erosion,inspecting stations were estabilished in the representative 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 eontrolling erosion were also done in terms of the inspecting techndogical standards of soil and water conservertion and actual circumatances of the rehabilitation area.We had inspected and studied the effects of Dayao's ecological rehabilitation project improving soil and controlling erosion one year with the traditional inspectability technology and "GIS" inspectability technology. We had brought folward perfect advice to the experimental unit project of Dayao ecological rehabilitation on the inspectability,analyses 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 84.10%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 had become the green mountain land.The succession of vegetable communities were becoming all right.The one-year inspectability and research,as follows conclusion:(1)Soil erosion of land types that adopted measures of the ecological rehabilitation was obviously controlled.Erosion modulus let up,and the erosion grand declined to light grade or lower grade,basically controlled soil erosion.(2)different vegations have different effect on soil erosionresistance factor.The benefit of woodland grassplot on reducing erosion is well.The erosion degree of uncovered ground is the most serious.According to the effect on water and soil conservation,woodland and grassplot are well than farmed land.Farmed land is well than uncover ground.The effect of woodland and grassplot on water and soil conservation is very well.Inaddition,the effect of aecommodating runoff,holding up mud-sand and reducing rainfall on clinohe erosion is obvious.(3)According site condition in mining areas,the goal of utilizing deserted land and vegetation restoration is attained by the selection of plant species and logical vegetation collocation.The community layout and configuration design in DaYao.(4)The factor of covering ground Cis the most important factor.Its essentiality can be proved by the relativity of practical surveyed data and calculated data.It is of benefit to soil erosion.(5)On the "grass-brush-woodland" land type series,there was a trend of the runoff 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 been controlled,the faint erosion area added and the light,middle,strong erosion area discreaed,and the quantities of soil erosion reduced from 1839110t to 592510t,lessened 69.87%.The faint erosion area increased from 55.919km~2 to 100.524km~2 and the average modulus of soil erosion declined from 5304.6299t/km~2.a to 1607.9809t/km~2.a.See from a angle of controlling 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 controlling erosion Will be the most remarkable.(6)The "arbor-shrub-grass" or "shrub-grass" pattern 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. Other wise the least rainfall intension(producing soil erosion)of the former 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.(7)On the "grass-brush-woodland" succession 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 controlling erosion and more remarkable effects of those. |
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