Study On Landscape Dynamics Of Sunite Desert-steppe

Desert-steppe mainly distributes on climate arid grassland district. Its area is large and distributes widely, and it plays an very important part in the grassland stockbreeding economy of our country. Because of the extremely harsh condition and the mankind's depredation using, original flimsiness grassland resources and ecosystem environment become more worse. In order to study desert-steppe landscape dynamics, open out the change of desert steppe landscape during the past 20 years fast and accurately, we use desert steppe investigation data of 1980s and early 2000s and two corresponding period remote sensing information images, then build up different translation marking, translate Remote sensing images, draw landscape types map,landscape dynamics map, compute landscape index depend on the techniques of remote sensing, geographical information system and global position system. Base on Grassland theory, Grassland ecology theory and Botany theory, colligating landscape pattern analysis method, landscape transition matrixes analysis method, changing between different landscape analysis method, landscape patch analysis method and landscape map dynamics analysis method, we analysis Sunite desert-steppe dynamics during the past 20 years, the results show that:Sunite desert-steppe grows 170706.80ha(5.22%), Patch size decrease, Patch shape index and landscape fragmentation index increase; Because the function of the dominance grassland landscapes play less important roles, the landscape diversity index and landscape evenness index increase, but landscape dominance index decrease, landscape is more heterogeneity, evenness and has lower stability, it has a trend to become even worse.The main change of Sunite steppe is between Typical steppe and Desert-steppe, many better steppe types and water degenerate to desert-steppe, the area shrink; But some areas of desert-steppe go to the bad, and city, field, factory, mineral area increase very quickly, they occupy many desert-steppe areas.The growth types of seven landscape types of Sunite desert-steppe in turn are: Sand landscape, Other Gramineouse landscape, Allium landscape, Artemisia landscape and Caragana landscape; The decrease types in turn are: Other Gramineouse landscape and Stipa landscape.Five patch types(grassland types) disappear during the past 20 years, they are Stipa glareosa,Cleistogenes songorica,Allium polyrrhizum, Stipa breviflora,Artemisia frigida,Cleistogenes songorica, Artemisia frigida,Lespedeza potaninii, Iris bungei,Stipa glareosa and Prunus mongolica,Stipa gobica; one patch type appear, it's Stipa gobica,Ajania achilleoides.The landscape richness index of different landscape of Sunite desert-steppe do not change much, most landscape types' landscape diversity index, landscape evenness index and landscape fragmentation index increase, but landscape dominance index decrease. Because of dominance patch types playing less important roles, different landscape types of Sunite desert-steppe are more evenness and fragmentation. Contract to other landscape types, landscape fragmention index of Allium landscape and Sand landscape become lower, landscape area increase, it is the reason why Sunite desert-steppe degenerate to sand; Some patch types of Artemisia landscape convert to dominance roles, Artemisia landscape's landscape diversity index decreases, its internal structure has a huge change, landscape situation turns better.