| Vegetation restoration is an important prerequisite for ecosystem restoration in coal mining area.Vegetation is an important part of arid and fragile ecological environment.Vegetation health affects the overall ecological quality of the coal mining area.Therefore,the core content of ecological restoration in western coal mining area is vegetation restoration.The main problems of vegetation restoration research are as follows: There are many single researches on vegetation damage and soil damage,but the research on the system level of vegetation impact in coal mining area is insufficient.The characteristics of vegetation-soil coupling damage under coal mining disturbance are not clear,the law of collaborative remediation is not distinct,and the mechanism of plant photosynthetic physiological restoration is not lucid too.On the basis of above considerations,Shendong coal mining area in Western China was taked as the target area.Based on literature analysis,the relevant research results were summarized,and the theoretical research framework of vegetation ecosystem resilience in coal mining area was initially constructed.Under the guidance of the framework,the impact of coal mining vegetation in the experimental area was studied.Firstly,based on the monitoring experiments in different stress areas,the mechanism of coal mining subsidence and its disturbance characteristics to vegetation habitat were preliminarily explored;secondly,the spatial differences of vegetation soil coupling damage in coal mining area were explored based on different scales by using unmanned aerial vehicle(UVA)and hyperspectral technology;finally,based on long time series,the dynamic characteristics of vegetation self-healing at different scales in the experimental area were analyzed to reveal the law of vegetation soil collaborative restoration and explore the Photosynthetic Physiological Mechanism of typical regional vegetation species.On the basis of the above research,structural equation model was used to quantitatively evaluate the resilience of vegetation ecosystem in coal mining area;Finally,combined with the evaluation results of vegetation resilience in coal mining area,the key time threshold points and typical areas of resilience enhancement were selected.Based on the low impact development technology and the ecological rain flood management model,the construction scheme of regional differential vegetation resilience was constructed.The main conclusions are as follows:(1)There are spatial differences in mining subsidence and environmental disturbance in western coal mining area.Under the condition of thin bedrock,thick coal seam and shallow deep fully mechanized caving,the surface movement has obvious spatial zoning characteristics,the maximum subsidence speed of goaf is larger than that of coal pillar area,step cracks appear at the surface interval above the goaf,and dynamic cracks appear near the boundary of working face;the soil in different stress areas is disturbed by the type and intensity of stress The degree of soil damage is different with different degrees,among which the soil water content,soil available nitrogen,available phosphorus and available potassium content are significantly different from those of collapse disturbance,which can be used as the key environmental factors for the later study of plant damage;(2)The coupling damage of vegetation and soil shows spatial heterogeneity.The disturbance of coal mining subsidence causes damage to vegetation health.The further analysis shows that the mining subsidence disturbance has a significant impact on the growth of trees and shrubs,but has little effect on herbs;The poplar,Caragana and Artemisia oil in different stress areas are damaged to different degrees.Caragana and Artemisia annua in neutral and compression areas are seriously damaged.The damage of poplar,Caragana and Artemisia oleifera in the extension area is relatively light,and the difference of stress areas of saphenocarpa is not obvious;Compared with the non coal mining area,the reflectance difference of different SPAD values of different plant samples in different stress areas is significantly reduced.At the same time,the characteristic bands of spectral index of typical plants in different stress areas under coal mining disturbance are preliminarily identified;The coupling damage evaluation of "vegetation soil" showed that both the community soil coupling damage and population soil coupling damage in the neutral area showed strong decoupling type,that is,the coupling between soil damage and vegetation damage was the worst.Meanwhile,Caragana korshinskii soil coupling damage showed strong decoupling type in different collapse stress areas,that is,Caragana korshinskii soil coupling damage was greatly affected by coal mining disturbance,which can be used as an individual recovery research in the later stage Study the typical plants;(3)The vegetation and soil collaborative restoration showed a periodic change rule.The ecological effect of mining subsidence disturbance on vegetation community is characterized by stages,that is,the process of community self restoration can be divided into primary stage(2 years,16 years),intermediate stage(1,3,4 and 12 years)and advanced stage(6,8,10 years).With the increase of restoration stage,the types and numbers of species have increased,and the dominant species changed from annual herb to perennial herb;the content of soil organic matter and available phosphorus was the main factor restricting the resistance of community;Soil water was the main limit of community restoration and robustness;Artemisia ordosica,Setaria setifolia,Kentucky bluegrass and Chenopodium glaucum are stress tolerant species,which are less affected by subsidence;They have good adaptability and strong resistance to barrenness;These species have strong self-healing ability and can be used as alternative species for vegetation restoration and reconstruction in coal mining area;The self-healing coupling types of community-soil in different restoration years belong to antagonistic coupling state,whitch of community-soil in CK,restoration 2a,6a and 10 a are in good coordination state,and the rest belong to moderate coordination state;The self-healing coupling types of population-soil belong to antagonistic coupling state,and the coordination degree type belongs to moderate coordination state;The self-healing coupling types of poplar-soil,Caragana-soil and Lespedeza-soil belong to antagonistic coupling state;The self-repair coordination type of poplar-soil and Caragana-soil in restoration 1a and 2a regions are in moderate coordination state;The self-repair coordination scheduling of Lespedeza-soil in recovery 2a region is higher than that in CK and recovery 1a area;It shows that the rough Cryptodon scabra recovers quickly after being disturbed;(4)The influence of environment on the resilience of vegetation system is greater than that of mining disturbance,The change characteristics of vegetation ecosystem resilience with restoration time were consistent with that of vegetation self restoration.At the system level,the impact of environmental subsystem on the resilience of vegetation ecosystem is greater than that of coal mining disturbance;on the factor level;The influence of mining depth on vegetation ecosystem resilience is greater than that of mining thickness,and the influence of growth environment system index factors on the resilience is in the order of soil water content,soil nutrient content and soil bulk density;The results showed that the vegetation ecosystem resilience was the lowest after 2 years of restoration,and then increased gradually.After 8 years of restoration,the vegetation ecosystem resilience was close to that of the control area,and then decreased gradually;The spatial differences of vegetation ecosystem resilience in the study area are as follows: in the second year of restoration(the lowest restoration period),the order of restoration capacity of vegetation ecosystem in each region is CK,compression area,stretching area and neutral area;(5)The construction scheme of Resilience Based on Low Impact Development(LID)can effectively enhance the resilience of vegetation system in coal mining area.The scheme can be applied in the practice of ecological restoration in the future.Under the background of one-year return period of rainfall intensity,the three sets of resilience construction schemes can significantly improve the resilience of the experimental area.With the increase of the rainfall intensity return period time,the effect of the three schemes to enhance the resilience of the experimental area gradually decreases,and the difference of the improvement effect of each scheme is larger and larger;The improvement effect of resilience of each scheme from large to small is resilience construction scheme 3,resilience construction scheme 2 and resilience construction scheme 1.This paper can provide theoretical reference and method reference for vegetation damage and restoration in western coal mining area.The research results have important practical significance to alleviate the pressure of water resources in western coal mining areas,promote ecological recovery of coal,and realize the sustainable development and utilization of coal resources.There are 77 pictures,61 tables and 246 references. |
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