Variation Of Vegetation Net Primary Productivity And Its Driving Factors In Shanxi Province

As the performance of vegetation growth,vegetation NPP is one of the important criteria for assessing the quality of the ecological environment.The growth and cover of vegetation deteriorated in part of Shanxi province caused by climate and human factors such as drought and mining,it's led to a series of ecological problems such as air pollution and soil erosion.The accurately grasp the status of vegetation growth and analyze the impact of climate human factors on vegetation in shanxi province can more scientifically and effectively manage and protect vegetation,thus solving the environmental problems such as soil erosion and air pollution caused by the reduction of vegetation,and alleviating the ecological pressure.The object of this study was to analyze the spatial and temporal variations of vegetation NPP in Shanxi province based on the NPP data of MODIS during 2005?2015.At the same time,the study investigated the effects of mining and climatic factors on change of vegetation NPP based on meteorological data.land cover type data and mining area data.The research results are as follows:(1)The average of vegetation NPP in Shanxi province during 2005?2015 was 326.5 g(C)·m-2·a-1,while those of grassland?farmland?shrub?forest was 300.3 g(C)·m-2·a-1,353.6 g(C)·m-2·a-1,366.5 g(C)·m-2·a-1,390.1 g(C)·m-2·a-1,respectively.The spatial distribution of annual average vegetation NPP in Shanxi province during 2005?2015 presented a increasing trend from west to east and from north to south(2)The annual maximum and average of vegetation NPP in Shanxi Province during 2005?2015 showing rising trend,the vegetation NPP in most areas showed an increasing trend and the area of 56.33%had a significant or extremely significant increase.The temperature and precipitation during growing season significantly affect the vegetation NPP,the vegetation NPP peak values appeared in the years with much precipitation and suitable temperature.The annual trends of different types of vegetation are same with the overall trends,the change of NPP in grassland and cultivated land was significant,and the NPP changes in forest lands and shrubs were relatively stable.(3)The NPP of all vegetation in the area below 1800m increasing with elevation rising,but it's obviously reduced in the area between 700m and 800m,when the elevation exceeds 1800m,the NPP of the forest land continues to increase as the elevation increases,the NPP of other types of vegetation remains basically unchanged and the vegetation NPP as a whole shows an increasing trend.The annual rate of change and the proportion of significantly or significantly increase area of vegetation NPP in the area below 1800m increasing with elevation rising,but it's obviously reduced in the area between 700m and 800m,when the elevation exceeds 1800m,it's gradually decreases.The change laws of grassland,farmland and shrubs are approximately same as overall vegetation,but the annual rate of change and the proportion of significantly or significantly increase area of shrubs NPP continue increase when elevation exceeds 1800m.Forest NPP decreased in areas below 1200m,and the decreasing trend increased with elevation increasing,the annual rate of change and the proportion of significantly or significantly increase area of forest NPP increased with elevation increasing when elevation exceeds 1200m(4)There was a positive correlation between vegetation NPP and precipitation,of which 6.93%showed significantly or extremely significant positive correlation,concentrated in the northern part of Shanxi province;There was a negative correlation between vegetation NPP and temperature,of which 3.66%showed significantly or extremely significant negative correlation,mainly concentrated in the central basin of Shanxi Province.The correlation between grassland NPP and precipitation is the best;the correlation between forestland NPP and temperature is the lowest(5)There is a large difference between the NPP of the mining area and its surrounding non-mining areas,the average value of vegetation NPP,annual change rate,and significantly or extremely significant increase in area proportion of the mining area are all smaller than those in the non-mining area,significantly or extremely significantly reduce in area proportion greater than the non-mine area.The climatic factors is not significantly differences in small area,indicating that mining is one of the important causes of significantly differences in NPP between the mining area and the non-mining area.