Spatial And Temporal Changes Of NDVI And ITES Influence Factors In The Hilly Red Soilregion Of South China

Vegetation as one of the important factors of soil and water loss in the region,has good benefits for soil and water conservation.The degree of regional vegetation coverage determines the degree of soil erosion in the region to a certain extent.The Hilly Red Soil Region of South China located in tropical and subtropical humid climate zones has large and concentrated precipitation.In addition,the regional topography has obvious fluctuation and high slope.The region has a large population density,active economic development,high level of urbanization,and obvious social changes.In the process of social and economic development,the region environment has been suffered strong artificial disturbances.Many factors have caused serious soil erosion in the region,making it the second largest soil erosion area in China,and seriously restricting the development of regional social economy.In this paper,the Normalized Differential Vegetation Index(NDVI)in the hilly region of southern China is the main research object.Using the MODIS NDVI product data and the NOAA NDVI dataset,the spatial variation characteristics and the changing trend of NDVI in different regions from 1985 to 2015 are analyzed.At the same time,combined with the characteristics of climate change,the residual analysis method was used to analyze the influence of natural environment and human factors on the regional NDVI changes.On this basis,the region was zoned based on socio-economic data,and the human activities in different regions were compared to regional vegetation.Change the law of change.The main conclusions are as follows:(1)From the perspective of time series,the regional NDVI has the trend of increasing first,then decreasing,and finally increasing.In terms of spatial distribution,NDVI is higher in areas with higher elevations and NDVI is lower in areas with lower elevations.At the same time,during the different periods,the proportion of regional positive NDVI growth area has decreased to increase,and the proportion of negative growth regions has shown a trend of increasing first and then decreasing.In terms of spatial distribution,negative growth regions and positive growth regions have distinct features in different periods.(2)The main driving factors affecting NDVI change include temperature,rainfall,population density,per capita GDP,and industrial structure.In the four periods,the influence of temperature in climate factors was greater than rainfall;The contribution rate of human factors was 39.25%,59.32%,78.61%,and 88.36% respectively,and the influence of human factors gradually increased.Regulation of national macro policies has significant impact on regional NDVI changes.During the period from 1985 to 1992,the rural household contract responsibility system for rural households was basically completed,and farmers' enthusiasm for production was improved,resulting in an increase in NDVI in agricultural activity areas.During the period of 1993-1999,the establishment of the socialist market economic system had a significant impact on the development of the regional society,which greatly promoted the adjustment of production and demand,and caused the predatory development of the regional economy during this period,resulting in severe environmental damage.As a result,the influence of human factors on the area has increased significantly,causing the regional NDVI to show a downward trend.In the period from 2000 to 2007,China's environmental protection has entered a stage of deep reform,the strategy for environmental protection has been gradually transformed,public awareness of environmental protection has been strengthened,and the implementation of ecological projects has promoted the increase of regional NDVI;however,the rapid development of the economy has accelerated the process of urbanization.The demand for resources has increased rapidly;this has led to an overall slow growth of regional vegetation.In the period from 2008 to 2015,with the further improvement of China's environmental protection system,regional development and the construction of ecological civilization are closely integrated,making the regional NDVI increase significantly.(3)Based on the statistical results of cluster zoning,it is shown that under the influence of different social and economic conditions,the change of NDVI has significant differences.The greater the population density,the greater the negative influence of human factors and the smaller the regional average NDVI.In the first three periods,the higher the level of economic development,the greater the negative influence of human factors,and the lower the intensity of human factors in the fourth period;the higher the level of regional economic development,the greater the destruction of NDVI by human activities.Seriously,at the same time,NDVI grows more slowly during the conservation process.