| As a typical ecologically fragile zone in China,under the new economic situation,the Loess Plateau region had many mines closed.Now it faces multipleplights,such as arduous ecological management task,social,economic and technical difficulties.Natural restoration as an ecological alternative strategy is gradually becoming an important way to solve the ecological problems in the Loess Plateau mining areas.However,whether or not the natural restoration is feasible,how to scientifically carry out natural restoration,are paid attention to.So through field research,experimental analysis and mathematical modelling,the thesis tried to explore the typical cases of natural restoration to reveal the mechanism and the nonlinear process of natural restoration,developthe scientific and technological procudure of ecological strategy decision-making.The main findings and conclusions of this thesis are as follows:(1)Fissures and landslides are the main disturbancesin the loess plateau mining areas,and there are objective facts of nature restoration.It was found with the investigation on the 75 exploitation working faces in the 7 mines of Shanxi Province that,the fissures and landslides have led to the abandonment of large amounts of used lands,the frequent occurrence of geological disasters and the death of vegetation,and they are the key ecological disturbances of the mines in the loess plateau mining areas,and they should become the focuses of regional ecological restoration.The dynamic fissures could be rapidly healed as the promotion of the working face while the marginal fissures would exist for a long time.However,even in the case of no human intervention,the number of marginal fissures and the intensity of the monomer could decrease over time.Even the secondary slope formed by the landslide,its vegetation coverage could be restored to the surrounding average level after many years' restoration,and has rich species and stable community.(2)The driving forces of natural healing of mining fissures are: coal mining,natural force and social and economic activity.Among them,the high-intensity soil and water erosion of the Loess Plateau is the main force for the healing of the marginal fissures.The natural restoration ability of fissures can be expressed as the function of fissure volume,provenance area,and supply modulus.The fissure healing time is negatively correlated with the development intensity(volume)of the fissure,which is positively correlated with the area of the source area and the supply modulus.(3)The driving forces of landslide vegetation restoration are: the changes of landforms,the soil seed bank,and social and economic activities,among which the seed bank is the main factor for the vegetation recovered rapidly in the earlier stage.The natural restoration ability of vegetation on the landslide surface could be expressed as the first-order ordinary differential equation of seed base content,soil nutrient,and slope vegetation coverage.The natural vegetation restoration time is negatively correlated with seed bank content,soil nutrient,and slope vegetation coverage.(4)The technological procedure of the ecological restoration decision-making in loess plateau mining areas includes: overlay analysis,the judgment(initial judgment)of restoration direction,the estimation of natural restoration time and tolerable judgment.The decision making should be comprehensively analyzed from productivity restoration and ecological function restoration.The empirical study on the No.1 coal mine of Yicheng County shows that 23 of the 48 fissures could be naturally restored,and 4 of the 5 landslide surfaces could be naturally restored,and theothers should be restored artificially. |
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