Satellite-based Ecological Assessment On Vegetation Restoration Around Mining Areas

The vegetation restoration has become one of the important means for the ecological reestablishment and improving ecological environment and quality in recent years.The traditional field monitoring method is time-consuming and laborious,and is difficult to provide complete information for the dynamic state of large ore group in the large scale vegetation restoration assessment monitoring in a short time.Therefore,the method of using advanced remote sensing technology to evaluate the ecological restoration of mining area was put forward after summarizing internal and external research status and development trend in this study.There representative open-air coal mine area(Dongsheng mine groups area,Shengli mine groups area and Baorixile mining groups area from west to east in the Inner Mongolia Autonomous Region)were selected as the researching areas,and the evaluating index system of mining area vegetation ecological restoration effect was designed in this study.Firstly,the 30m TM/ETM was as data source for interpretation of land use type of three ore cluster in 2000 and 2010 according to the index system,corrected land use data using mine vector figures from mining department,and the land use type data in 2000 was used as the background data.Secondly,the ore zone evaluation index were inversed using model based 500m MODIS products(including vegetation index,leaf area index,surface temperature and surface albedo),meteorological data,soil data,and digital elevation data from2000 to 2015.The inversion process and flux observation data are used to verify the performance of the partial model.Finally,the ecological engineering measures in the three ore mining areas were evaluated based on the remote sensing inversion indicators from the temporal and spatial pattern change and the effect of the vegetation restoration.The methods of the space instead of time and the difference of restored area and mine area(the bottom value)were mainly used for comparing vegetation restoration effect in the quantitative assessment of vegetation restoration process.The remote sensing method had high coverage,low cost,and comprehensive evaluation compared with the traditional method,which applies comprehensive index system,attends the macro structure of ecosystem change,carbon sequestration,soil and water holding function,and climate regulation function,and also evaluates effect of ecological restoration in mining areas.The main results were shown as follows:(1)The remote sensing monitoring results showed that the macro ecosystem structure of Inner Mongolia opencast coal mine areas changed significantly,independent mining land area of settlement ecosystem sub-types increased,the forest,grass and agricultural ecological system were mainly mining land at the expanding independent industrial mine areas during 2000-2010 years..The index trends of vegetation coverage and leaf area were increased at three mining clusters areas.(2)The net ecosystem productivity of three mining areas increased.The increase rates of Dongsheng,Shengli and Baorixile mining areas were 0.3 gC/m~2(p=0.223),0.3 gC/m~2(p=0.461)and 0.4 gC/m~2(p=0.463)per year,respectively.Although carbon sequestration function of the ecological system in the majority mine areas was restored,the measures and the speeds from artificial promoting recovery were insufficient.(3)Soil and water holding performance of mining areas increased,and inter-annual variability fluctuated significantly.The fixed sand service function from the vegetation restoration showed positive growth(p<0.01).The increasing rate for fixed wind and sand in Dongsheng mining area was 0.016 t/hm~2/yr,of which in Shengli and Baorixile mining areas were 0.039 t/hm~2/yr and 0.282 t/hm~2/yr,respectively.The mount of Increasing water conservation capacity in Dongsheng,shengli and Baorixile mine areas were 0.039 t/hm~2/yr(p<0.01),0.145 t/hm~2/yr(p<0.01)and 0.148 t/hm~2/yr(p<0.05),respectively.(4)For climate regulation of the vegetation restoration,the cooling effect were all observed in three mining areas.Annual decreasing rates of evapotranspiration in Dongsheng,Shengli and Baorixile mining areas were 0.024 W/m~2(p<0.01),0.097W/m~2(p<0.01)and 0.016 W/m~2,respectively which do not reach statistical significance(p>0.05)..The surface temperature decreased 0.008?(p<0.05)every year in Dongsheng mining areas,and 0.007?and 0.001?in Shengli and Baorixile mining areas,respectively,which did not differ significantly(p>0.05).