Ecological cumulative effect of mining area in typical arid and semi arid grassland

Located at the upper and middle reaches area of the Yellow River,the arid and semi arid grassland region of Inner Mongolia is the ecological safety region known as the “Two Barriers and Three Belts”,which includes many largescaled coal mines and coal fired power plants in China.The longterm growth and spatial expanded coal mining behavior have caused severe impacts on the mining area and surrounding ecological environments such as land degradation,groundwater decline and depletion,and biodiversity loss.Issues in this area have been raising concerns of the country and society which demands further research on the cumulative ecological effects.Past researches mainly focus on the analysis of the ecological effect of a certain ecological element or a certain period of time in arid and semi arid grassland mining areas,however,the development of coal mines has a life cycle and complicated energy and material flow.This paper consists of three main parts:① The related research projects of arid and semi arid grassland mining area in the world were reviewed.The life cycle stages of coal mines were analyzed,and the spatial relationship between different life stages development of mining area and the evolution of grassland ecosystem was provided.② The accumulative characteristics of ecological effects in arid and semi arid grassland mining area in eastern Inner Mongolia were analyzed,and the accumulation sources,accumulation methods and representation forms of key ecological elements of water,soil and vegetation were emphasized.By using trend line analysis method,the temporal and spatial cumulative change trend of vegetation coverage in eastern Inner Mongolia was analyzed.The results showed that 61.29% of the pixel vegetation coverage in eastern Inner Mongolia were subtly changed from 1981 to 2015,about 16.86% of the pixel vegetation coverage in the northwest of Tongliao City,the north of Chifeng City,and the central area of Hulunbuir tended to decrease,and about 21.85% of the pixel vegetation coverage in the west of Hulunbuir,the south of Xing’an League,Chifeng City,and the southwest of Tongliao City tended to increase.③ Based on the mechanism of the land environment ecological accumulation response,the relationship among ecological carrying capacity,ecological accumulation effect and ecosystem elasticity were explained,and the technical path of elastic regulation was proposed.Quantitative research on the ecological cumulative effects of the entire life cycle of coal mines is a promising way to understand the evolution patterns of ecosystem in grassland mining area,and build theoretical and practical foundations for ecological restoration in arid and semi arid grassland mining area.