| Coal mining is the lifeblood of national economic development,but it has caused a series of ecological problems such as vegetation degradation,soil erosion,confusion of ecological structure and decline of ecological function,which has seriously affected the ecological stability of semi-arid open-pit coal mining area.It is particularly urgent to realize the ecological sustainable management of open-pit coal mine area.It is an inevitable requirement for the sustainable development of ecological environment in open-pit coal mine area to clarify the spatio-temporal dynamics variation of ecological stability and explore its maintenance method of ecological stability in open-pit coal mine area.However,there are still the following problems in the present research on this issue: the ecological environment effect of open-pit coal mine area under mining disturbance is unknown,the connotation and measurement framework of ecological stability in open-pit coal mine area are unclear,and the research on the maintenance method of ecological stability in open-pit coal mine area is also lack of attention.Therefore,aiming at the problems of ecological structure change,ecological function loss and ecological instability under long-term and high-intensity mining in the semiarid open-pit coal mine area,Jungar Banner open-pit coal mine area was considered as the target area.Firstly,the connotation of ecological stability in the open-pit coal mine area was defined through literature research and concept discrimination,and the formation basis and influencing factors of ecological stability were studied,the theoretical framework of ecological stability measurement based on structuralfunctional state transition was preliminarily constructed.On the basis of the above study,the maintenance mechanism of ecological stability in open-pit coal mine area was summarized.Secondly,3S remote sensing technology and field investigation were used to study the sub scale eco-environmental effects under mining disturbance.Next,based on the ecological stability measurement framework,the measurement model and index system were constructed to reveal the spatio-temporal dynamics variation law of openpit coal power base and single mining area.And the maintenance mechanism of ecological stability was summarized according to the scale differences and management objectives.Finally,optimize the spatial and quantitative distribution and connectivity of key components and parts through green ecological pattern and low impact development of water and soil regulation,so as to optimize ecological structure and improve the corresponding ecological function,and realize the maintenance methods and technologies of ecological stability combining the whole and part.The research results are as follows:(1)On the basis of concept discrimination,induction and summary,this thesis defines the connotation of ecological stability in open-pit coal mine area.The subject of ecological stability research in open-pit coal mine area can be divided into coal power base,single mining area and specific individual according to different scales,and the object is coal mining disturbance or other disturbance.From the system level,the existence and interrelated feedback of various components in the open-pit coal mining area are discussed,leading to the formation of structure and function,during which the ecological stability can be formed.The influencing factors of ecological stability in open-pit coal mine area are mainly natural factors and human activities.The interaction of various factors is the basis of affecting the ecological stability.Based on above,taking the change of ecological stability corresponding to the transformation between different structures and functions as the starting point,a theoretical measurement framework of ecological stability based on structural-functional state transition is proposed.Meanwhile,this thesis takes "influencing factors-relationship-structurefunction-stability" as the main line,the maintenance mechanism of scale ecological stability of open-pit coal power base and single mining area is summarized.(2)Ecological environment change is a direct manifestation of the change of ecological stability.The ecological environment effects caused by mining disturbance have spatial differences.Open pit mining activities lead to the breaking of the connectivity between patches,the increase of heterogeneity and landscape fragmentation,and the gradual trend of land use structure from order to disorder.From2000 to 2017,the vegetation coverage of Jungar Banner open-pit coal power base increased first,then decreased and then increased.The vegetation coverage was mainly of medium and low variability.Regional vegetation restoration will significantly make up for the negative impact of mining activities on vegetation.The overall trend of soil erosion in open-pit coal power base was opposite to that of vegetation coverage and the severe erosion was mainly distributed in the excavated area and surrounding of openpit coal mine in each mine group.The total primary productivity of vegetation showed obvious aggregation.The emergence of coal mining activities will increase the spatial variability of total primary productivity and reduce the spatial autocorrelation.With the increase of vegetation reclamation activities,the total primary productivity increased,the degree of spatial variation decreased,and the spatial autocorrelation increased.There were significant differences in vegetation community structure between different reclamation years.The contents of total salt,organic matter,total nitrogen,available nitrogen,available potassium and available phosphorus of soil fluctuate and increase with the increase of reclamation years,and the soil bulk density decreases with the increase of reclamation years.With the increase of reclamation years,the characteristics of vegetation community structure and soil physical and chemical properties in the reclaimed area will gradually improve and influence each other,which can even surpass the natural areas.(3)From 2002 to 2017,the ecological stability of Jungar Banner coal power base showed an improving trend,and it presented an overall sub-stable and local extremely unstable state.The extremely unstable and unstable areas of Jungar Banner coal power base were mainly distributed in the northern area,open-pit coal mine excavation area and around towns in Jungar Banner.It was found that the degradation rates of structure and function were 1.7-4.7 times and 1.3-5.2 times of the recovery rate,respectively.In the process of negative state transition,the structure and function were easy to degenerate;In the process of forward state transition,it took a long time for the structure and function to recover to the state before mining disturbance.The ecological stability of a single mining area showed a logistic growth trend,mainly divided into three stages:initial adaptation period,rapid improvement period and stable growth period.After 3-5years of reclamation was the stage of rapid improvement of ecological stability.The development degree types of vegetation and soil corresponding to the same ecological stability in different mining areas are different,and artificial restoration can make the development of vegetation soil more coordinated.(4)The ecological stability of open-pit coal mine area was affected by both natural and human factors.Before 2008,the factors affecting the ecological stability of openpit coal power base was in order of rainfall,vegetation coverage,distance from the nearest construction land and distance from the nearest mining area.After 2008,with large scale expansion of mining land,the factors affecting the ecological stability of open-pit coal power base was in order of distance from the nearest mining area,rainfall,vegetation coverage and distance from the nearest construction land.Soil water content and vegetation restoration years are the key factors affecting the ecological stability of a single mining area.The interaction of various factors was the basis of affecting and maintaining the ecological stability of the system.Affected by different factors and goal oriented,the maintenance mechanism of ecological stability in different regions and stages will be different.In the open pit coal power base,focus on the areas with declining in ecological stability,it could reduce land occupation and land fragmentation through contiguous governance and build ecological patterns to improve pattern connectivity and integrity,and achieve multi-functional characteristics of land and enhance ecological diversity through differentiated reclamation,which can finally maintain regional ecological stability through structural adjustment and function improvement.In a single mining area,drought adaptation and water self-regulation were the primary mechanisms to maintain ecological stability.In addition,vegetation,soil moisture and soil regulation should be carried out reasonably according to different stages of ecological stability development.Thus,the ecological stability can be improved and maintained by improving the diversity of vegetation community structure and soil environmental factors.(5)It is proposed to optimize the spatial and quantitative distribution and connectivity of key components,structures and parts by building a green ecological pattern and locally implementing low impact development technology,so as to maintain regional ecological stability with optimizing ecological structure and improving ecological function.1)Study on ecological stability maintenance method of open-pit coal power base:On the premise of ensuring the coordination of the optimization of the green ecological pattern and the development of future policies,the optimal target scenario in 2030-ecological-economic equilibrium scenario was determined,and the ecological pattern of this scenario was optimized.After optimization,this scenario could ensure that the existing extremely stable and stable areas were away from damage to the greatest extent;and the ecological sources within the coal mine groups increased,ensuring a more balanced distribution of ecological sources;the density of ecological corridors in the west and north of the study area increased,making the overall network connectivity better than 2017;at the same time,the number of optimized first-level ecological nodes increased,which has played an important role in improving the connection efficiency of the overall ecological pattern.In general,the optimized optimal target scenario in2030 can maximize the landscape connectivity and regional structural integrity of the open pit power base in Jungar Banner,and at the same time,it could give full play to its ecological service function under the premise of ensuring the balance and maximization of ecological and economic benefits.Based on that,the aim of maintaining ecological stability was realized through optimizing regional ecological structure and enhancing ecological function.2)Study on ecological stability maintenance technology of single mining area: By determining the key source areas and laying surface water storage and water release LID ecological facilities such as reservoirs,ecological detention ponds,grass planting ditches and vegetation buffer zones in the key parts,the purpose of reduce the amount of surface runoff and nitrogen and phosphorus loss,improve the ecological utilization efficiency of water resources and soil nutrient retention were realized,so as to optimize the vegetation-water system pattern and form the maintenance technology of ecological stability in local key parts.The research of this thesis can provide theoretical reference and method reference for the ecological management and sustainable development of open-pit coal mine.The research results have important practical significance for maintaining the ecological stability of open-pit coal mine,optimizing ecological pattern of open-pit coal mine area,alleviating the pressure of water resources and promoting the ecological restoration of mining area.There are 73 pictures,36 tables and 265 references. |
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