Identification Research On The Vegetation Spatial Pattern And Its Influence Factors Based On Multi-scale Remote Sensing In Horqin Sand Land

The ecological system of drought and semi-arid region area is vulnerable, and the variation of vegetation cover is large obvious, it is particularly important to provide a theoretical basis for combating desertification through explicating the vegetation cover pattern of desertification area and determining its variability of spatial-temporal and the relationship with hydrologic meteorological factors.In this study, it takes horqin sandy land of the typical desertification in the north of our country as study area, extract soil regulate vegetation index (SAVI) using the resolution imaging spectrum radiometer (MODIS) surface reflectivity product data and the Aster data, analysis the variability of spatial-temporal of SAVI in the study area through the information entropy theory in typical study area scale. Taking the correlation analysis to clear the relationship among the change of the vegetation cover and the precipitation and temperature further. As a whole, the eastern growth situation of vegetation in the study area is better than western, and south is better than north. The spatial-temporal variability of vegetation pattern is largest in2005, and2000is against in time; and it is largest in southwest instead of southeast in the space precipitation and temperatures are positively correlated with SAVI, and precipitation have the larger effect on SAVI. at the same time, to study the response relation among different landscape types of vegetation and underground water level, potential evapo-transpiration, the surface soil moisture content (0～30cm); sunshine time and geothermal (0～30cm) through correlation analysis in key study area scale. The lag time of the underwater level for the vegetation growth is about2～4weeks; potential evapo-transpiration and the vegetation growth are synchronous, so the lag time is not obvious; in addition, the lag time of the surface soil moisture content, sunshine time and geothermal respectively are2weeks,40days and35days. Finally, taking the features spectrometer(ASD) to measure the spectral reflectance and to compare the spectral characteristics of different kinds of vegetation in the key study area. We can conclude that Artemisia halodendron, Ephedra distachya, Salix flavida and Caragana microphylla have the same spectral characteristics:it appears absorption troughs at about500nm and smaller reflectance peaks at550nm of the visible light; it emerges distinct absorption troughs at about680nm and peaks at700～750nm next, the reflectance rises dramatically in different degrees, which is called "red edge" in the spectral research. At the same time, due to the reason, the rest of the10planting have lost chlorophyll and become yellow, which have not shown the spectral characteristics as normal vegetation.