Spatio-temporal Differentiation Of Vegetaition Coverage In Qinhe Basin

Vegetation coverage,as an important indicator of land vegetation status,plays an important role in indicating the environmental changes of regional or global ecosystems,so it has always been widely concerned by scholars in the field of ecological environment.Qinhe Basin in Shanxi Province is an important soil and water conservation,water conservation and biodiversity reserve in southeastern Shanxi Province.In recent years,with the rapid development of watershed economy,it has brought a lot of ecological environmental problems to the management and development of watershed,Therefore,it is necessary and urgent to grasp the vegetation cover information timely and accurately and carry out the ecological restoration and protection planning in the region.at the same time,it can also provide a powerful guarantee for the realization of comprehensive and coordinated sustainable development of ecological civilization and economic society in the region.In view of this,this paper relies on the project of "Research on Comprehensive improvement of Land in Northern villages and Hilly areas of Coal pressure",By analyzing the existing data,the Qinhe Mainstream Watershed is selected as the research area.Taking 4 images of Landsat TM/OLI as data source,fractional vegetation coverage(FVC)in Qinhe Basin were estimated by dimidiating pixel model,and the spatio-temporal changes of vegetation patterns from 1993 to 2016 were analyzed using transition matrix,geo-spectrum and center of gravity migration model.Meanwhile,the spatio-temporal variation of vegetation at different attitudes,slopes and aspects were explored based on topographic factors.The main results are as follows:(1)The spatial distributing trend of FVC was great FVC in the northwest and low FVC in the southeast,and the vegetation growth in both banks and downstream areas is poor.the FVC in the Qinhe Basin showed an increasing trend with no significant fluctuation,and the area of Class I and II declines by 22.18%,the area of Class IV and V increases by 25.24%,and the area of Class III basically remains stable.(2)From the perspective of transfer matrix,the greatest FVC increased from south to north,and it was mainly transformed from the sub-level vegetation.Thesequence analysis of Vegetation Spectrum shows that the type of vegetation Spectrum in the watershed was dominated by repeated change type,followed by the change type of early stage and later stage,and the proportion of middle and continuous change type is the smallest.(3)The migration of gravity center of FVC shows that the higher the vegetation grade is,the more north the center of gravity is,and the most obvious gravity center migration is in category IV and V.The overall resault is that the center of gravity for FVC was migrated toward the southeast about 2.05 km.(4)FVC values in Qinhe Basin were significantly positively correlated with elevation and slope,the area of remarkable improvement increased and then decreased with elevation and slope,and the sudden change point is 830m-957 m and7-12 degrees,but not remarkable with aspects,the favorable terrain of vegetation in aspect was the area of the northeast,northwest and southwest.(5)The difference of vegetation cover change spectrum in different terrain factor gradient: The area ratio of the s[ectrum type is mainly dominated by the change pattern and the most obvious by the altitude gradient,The proportion of changeable and stable types on slope and aspect are relatively stable.Among them,the vegetation coverage changes most significantly in the elevation of 830-957 m,slope of 3-7 degrees and the direction of southwest.