Evaluation Of Artificial Restoration Effect Of The Abandoned Mines In Beijing

In recent years, Beijing government artificially restorated the abandoned mines in Beijing with engineering means. For studying the recovery effects and comprehensive evaluation of abandoned mines, the research investigated MTG(MenTouGou) Lime mine, MTG (MenTouGou)Coal mine, TMG(TanMuGang) Quarry and LGZ(LiGeZhuang) Quarry. Thorough investigating and anglicizing soil physicochemical properties, plant species and soil seed bank, the experiment inspected restoration effects of the abandoned mines and found the limit factors of ecological recovery. Through the grey relational analysis and fuzzy evaluation based analysis on analytic hierarchy process (AHP), the experiment also sequenced ecological recovery effect of abandoned mines. The experiment provided technical support for project restoration of abandoned mines in Beijing.Through the analysis, the conclusions as follows:(1) There were extremely significant differences of soil physicochemical effect between restored region and undisturbed region, destroyed region. The soil physicochemical properties of restore region were significant improved. There were also extremely significant differences between restored region and undisturbed region in 4 mines, which mean the soil need going on retorting.(2) The soil remediation limit factors were found with single factor hypothesis test. MTG lime mine should focus on improving soil organic matter, available nitrogen and total nitrogen; MTG coal mine should focus on improving soil organic matter, available nitrogen, available phosphorus and total nitrogen; TMG quarry should focus on improving soil organic matter, nitrogen and total nitrogen; LGZ quarry should focus on improving soil density, field capacity, available nitrogen, available potassium and total nitrogen.(3) The soil water holding and supplying capacity were improved obviously of abandoned mines in Beijing; the formula (θ=aS-b) can well described the relationship between soil water and pressure; 0.1 MPa can be determined as boundaries suction values between the soil effective water and hard water.(4) The plant community composition was high similar between restore region and original region. The plant community properties of restoration area had been significantly improved and the stable plant community in early succession stage was built. Poaceae, Asteraceae, Verbenaceae, Leguminosae were dominant family in the new plant community. It was artificial planting plants including Medicago sativa Linn, Cosmos bipinnata Cav., Lonicera Japonica, Robinia pseudoacacia L, Ulmus pumila Linn, Populus davidiana Dode in the new community that had a higher importance value and the good adaptability. But the proportion of trees and shrubs was relatively low, which mean it taken a long time to reach the same ecological effect as original region. (5) The soil seed bank properties of restoration area had been significantly improved. The restoration potential of restore region was closed to original region which mean they had same vegetation regeneration ability. Asteraceae and Poaceae were dominant family in the soil seed bank of abandoned mines in Beijing. It was artificial planting plants including Ulmus pumila Linn, Robinia pseudoacacia L and Cosmos bipinnata Cav. that could propagate with them which have contribute to the stability of plant communities. The recovery force of soil seed bank had accelerated the ecological recovery rate.(6) The evaluation model based on AHP can be used to ecological rehabilitation effect evaluation of abandoned mines in Beijing. It was proved that the results of the grey relational analysis and the fuzzy evaluation system are highly consistent, which mean two kinds of evaluation methods were effective.a. Through the grey relational analysis based on AHP, the sorting of 12 sites' ecological recovery effect is as follows:Original region of MTG Coal mine> Restore region of MTG Lime mine> Restore region of TMG Quarry>Original region of LGZ Quarry> Original region of LGZ Quarry> Original region of TMG Quarry> Restore region of MTG Coal mine> Restore region of LGZ Quarry> Destroy region of MTG Coal mine> Destroy region of TMG Quarry> Destroy region of LGZ Quarry> Destroy region of MTG Coal mine.b. Through the fuzzy evaluation system, the sorting of 12 sites' ecological recovery effect is as follows:The quality evaluation of Original region of MTG Coal mine, Restore region of MTG Lime mine, Restore region of TMG Quarry and Original region of LGZ Quarry is the "excellent"; The quality evaluation of Original region of LGZ Quarry, Original region of TMG Quarry and Restore region of MTG Coal mine is the "good"; The quality evaluation of Restore region of LGZ Quarry is the "Medium"; The quality evaluation of Destroy region of MTG Coal mine, Destroy region of TMG Quarry, Destroy region of LGZ Quarry and Destroy region of MTG Coal mine is "bad".