| Coal has always occupied the primary position in Chinese production and consumption structure.However,the original geological structure,hydrological cycle,landscape pattern and surface ecosystem of the mining area have changed due to the large-scale mining and unreasonable utilization of coal resources,and the stability of the mining area’s ecosystem and sustainable social development have been seriously threatened.At present,the research on the change trend of ecological landscape on coal mining areas is mainly focus on the overall level of the region,while it is slightly lacking for the comparison of the ecological evolution trend after mining on different landform under the same climatic conditions,which affects the accuracy of the ecological environment quality evaluation and and the pertinence of ecological restoration strategy formulation on the mining area.Based on the Landsat data from 1990 to 2019,using pixel dichotomy,transition matrix method,landscape pattern index method,this studied took the Yushenfu mining area as an example to explore the temporal and spatial distribution and evolution characteristics of vegetation coverage,land use,and landscape ecological pattern of loess hills and sand-covered land on the loess hilly area and windy sand land on the Yushenfu mining area,and to comprehensively evaluate the ecological sensitivity of Yushenfu mining area based on the above research results.The results showed that:1.The average vegetation coverage increased in the Yushenfu mining area from 1990 to 2019,and the improvement of vegetation area was three times than that of the degraded area,and the increasing rate of vegetation coverage was greater after 2005.In different landforms,the average growth rate of vegetation coverage on the loess hills was about twice that of windy sand,and the distribution levels of the main vegetation coverage in the two areas ranged from 30%to 45%and 15%to 30%,respectively,but the vegetation coverage showed a downward trend on the loess hilly area from 1990 to 1995 and on the windy sand land from 2000 to 2005.In the past 30 years,the gravity center grade of vegetation coverage in the study area had increased sequentially from southwest to northeast,and moved to the southwest.The center of gravity of vegetation coverage shifted the most from 2000 to 2011.During the study period,the length of the long axis of the standard deviation ellipse was 2 times the length of the short axis times,and the whole ellipse was gradually deflected in the counterclockwise direction,and the shape index remained stablly.2.From 1990 to 2019,the main landscape type in the Yushenfu mining area was grassland,accounting for 62%of the area.During the 30 years,different land uses had changed significantly,and the most obvious was from 2000 to 2011.2173.44 km2 of land use types have been transferred,and the forest area had increased by 642.13 km2,mainly from grassland and cultivated land.From 1990 to 2019,the building land on the loess hilly area and the windy sand land showed an increasing trend in different landforms,and their area increased by 1.36 times and 5.58 times,respectively.The largest increase in building land in the two landform types was from 2000 to 2011,and their areas increased by 75.05 km2 and 84.58 km2,respectively;the main period of forest land increase in the two landform types was 2011-2019,and the forest land area more than doubled;from 1990 to 2019,the grassland and cultivated land areas on the loess hilly area decreased by 27.78%respectively and 42.13%,while the cultivated area on the windy sand land showed an increasing trend,and the area increased by 174.92 km2;the area of sandy land and bare land in the loess hilly area changed little,but in the windy sand land,it showed a significant downward trend,and the area decreased by 594.54 km2;in the past 30 years,the water area of the two landform types did not change significantly.3.Based on the grain size effect map of the landscape pattern index in the Yushenfu mining area,60 m was determined as the best analytical grain size to study the evolution characteristics of the landscape pattern in study area.From 1990 to 2019,the landscape fragmentation and diversity index of the Yushenfu mining area continued to increase,the patch aggregation and dominance decreased,and the landscape patches tended to be complicated.In different landforms,the fluctuation range of the landscape pattern index in the loess hilly area was greater than that in the windy sand land,the largest patch index decreased from 24.16 to 8.36,and the landscape shape index and diversity index increased by 8.1%and 15.68%,respectively,this shows that the landscape pattern in the loess hilly area tends to be fragmented and complicated;while the landscape pattern in the windy sand land was well integrated,the patch cohesion index of each type is 92.32-99.04,and the evenness index increased from 0.57 to 0.71,which indicated that the landscape connectivity and high scalability,but low degree of fragmentation.4.Based on the analysis of the temporal and spatial change characteristics of vegetation coverage,land use and landscape pattern,combined with the analysis results of soil erosion intensity in the study area,the ecological sensitivity of Yushenfu mining area was evaluated.The ecological sensitivity in the northeast and south of Yushenfu mining area was higher than that in the middle,and the ecological sensitivity in the loess hilly area was higher than that in the windy sand land.Highly sensitive areas and extremely sensitive areas were mainly located in the areas of key coal mining and economic activities.In the process of coal resource development,this area needs to adhere to green mining and implement ecological restoration projects.Moderately sensitive areas were mostly located in the transition zone from loess hilly area to windy sand land,it is necessary to adhere to limited water retention,prevent water inrush from the water retention stope,and strengthen the work of mining and repairing at the same time.The slightly sensitive and insensitive areas were mainly located in the windy sand land in the middle.After the ecological disturbance caused by coal development in this area,it is necessary to further expand the vegetation coverage area according to local conditions and promote the stability of ecosystem structure and function. |
