| The land degradation in northern China is the main form of desertification,It is mainly because the ecological system is disturbed,resulting in the destruction of ecological balance,resulting in the process of vegetation and environmental degradation.Hunshandake in Xilin Gol league prairie central region of Inner Mongolia is sensitive to change in the environment,but also the fragile ecological environment area,is the nearest source of Beijing,Tianjin and Hebei region in China.For a long time,due to natural climate drought and the impact of human activities is becoming more and more frequent,coupled with the relevant departments of management efforts on the grassland is not enough,intensified desertification process in the region,restricted the development of local economy.Since twenty-first Century,the frequent occurrence of dust storms has been a serious threat to the surrounding areas,especially the capital of Beijing,the sustainable development of ecological environment.However,how to scientifically understand the Hunshandake Sandy Desertification in recent30 years,the development and changes of ecological environment and the Hunshandake Sandy Land Restoration and management to provide a scientific basis,is an urgent question.Based on this,this paper studies the status and trend of desertification in the sandy land in the past 30 years by using TM images of low resolution remote sensing data from1987-2016 and MODIS data products as the data source.The main work is as follows:the 9periods(1987,1989,1993,2000,2002,2007,2010,2014,2016)covering the Hunshandake sand body and the surrounding area of Landsat 5 and Landsat 8 series of satellite data,taking into account the seasonal characteristics of Hunshandake sand,extracted by normalized vegetation index(NDVI),vegetation coverage remote sensing technology(VC),modified soil adjusted vegetation index(MSAVI),normalized difference water index(NDWI)index data, as well as the combination of short wave infrared band and thermal infrared band,regional parameters such as regional elevation and slope,the index data and parameter data information superimposed to form new multi band data.According to the relevant research data and regional Google earth image,the spectral information of the multi band data was analyzed,and the threshold range was divided.Make full use of the multi band data index information in decision tree classifier,vegetation and water layer to eliminate non desert characteristics of surface information,the temporal information of desertification in Hunshandake sand body distribution,finally analyses the dynamic characteristics of desert hinterland and edge desertification.The experimental results show that the method adopted in this paper can be used to extract desertification information accurately and the accuracy of decision tree classification is more than 80%.From 1987 to 2000,the main area of Hunshandake Sandy Land desertification area increased,by the end of 2000,the desertification area increased from26000km~2 in 1987 to 30000 km~2 in 2000,13 years of desertification area increased by 4355km~2;After 2000,the situation of desertification in Hunshandake sandy land has been improved,and even showing reduce trend,performance as the Hunshandake Sandy Desertification in northern edge and Duolun county and Zhenglanqi of southern area are significantly alleviated,the vegetation coverage has generally increased.But the Zhengxiangbaiqi,Xianghuangqi and the eastern edge of the Hexigten desert land appeared to the margin expansion trend,of which Hexigten desertification land increased most significantly.The water area of the main body of the area in the main area of the Hunshandake sandy land showed a decreasing trend in the past 30 years.In 1987,the area of the lake was about 850 km~2,and in 2016,the area of the lake was only about 530 km~2,which decreased by nearly 37.65%,water area decreased 214km~2during 1987 to 2000,deceleration rate slowed down after 2000.Using MODIS 2000-2016 data products for 17 consecutive years of growth,the use of vegetation index(NDVI/EVI)data products,net primary productivity(NPP)products,gross primary productivity of vegetation products(GPP),from the Hunshandake Sandy Desertification Region of the vegetation growth status and biomass change angle,analyzes the influence of vegetation change on area and biomass changes of the development process and the evolution trend of desertification.The results showed that the main area of Hunshandake Sandy Land and surrounding region,vegetation coverage increased from 2000to 2016,nearly 17 years.Desertification status has been obviously improved,which also shows that the local government of the sand and sand control project has achieved remarkable results.But analysis from the perspective of biological productivity,NPP/GPP was low,and the growth is not significant,indicating that the ecological environment carrying capacity of Hunshandake Sandy Land regions still very fragile,in order to improve the local ecological environment,the prevention and control of desertification still need to be intensified. |
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