Study On The Dynamic Change Of Landscape Pattern In Xilin River Basin

Relying on the3S technology, as the support of landscape ecologyprinciples and DEM method, using the mathematical statistics andmathematical modeling, and remote sensing images as the main datasource, this study quantitatively analyzed the changes of landscapepattern and influencing factors of the Xilin River Basin from1990to2010, and exploring the eco-environmental effects brought by thischanges.The main results of this study are as follows:(1)Landscape Pattern analysis shows that: Types of landscape arericher and these phases show an uneven distribution. Grassland landscapeof the Xilin River Basin is an advantageous landscape with highconnectivity, accounting for about92%of the watershed of total area, inwhich high and medium coverage grassland landscape achieved about90%.(2) Dynamics studies of the landscape pattern have shown that, XilinRiver watershed landscape pattern changed obviously during1990-2010:In1990-2000, the basin landscape pattern changes are mostlyconcentrated in the basin midstream and downstream areas, the largestincrease appeared in the sandy landscape and the salt marshes landscape,water landscape and the high covering grassland landscape are mostlyreduced; In2000-2005, the high covering grassland landscape increasedsubstantially, increasing speed of water landscape, urban landscape andconstruction land landscape is faster, and the sandy landscape and thesalt marsh landscape rapidly decreased; In2000-2005, the woodlandlandscape, cultivated landscape, high coverage grassland landscape andwetlands landscape are gradually reduced. During the three periods of study, the changing pattern of the ecological environment of this basin is“deterioration-improvement-deterioration”. Grassland landscape changeis most obvious, followed by water landscape, sandy landscape, thelandscape of salt marshes and construction land landscape.In1990-2010, the index changes of various landscape types isdifferent in the study area, the fractal dimension, diversity index,evenness index and fragmentation index of the landscape of the XilinRiver Basin have been increasing the past20years, and the contagionindex has been declining. The original single, homogeneous andcontinuous distribution of the overall landscape due to complex, and theheterogeneous and discontinuous patches misacted.(3) Landscape pattern based on DEM analysis results show that:Most of the landscape area of the study area is located below elevation1400m,landscape pattern change is mainly concentrated in1and2below1300m elevation zones; At the slope level, Landscape type is mainlydistributed in the following10°sloped area, and landscape pattern changeis mainly concentrated in the following7°flat ground and slow flatground; At the aspect-level, the landscape pattern and change of the studyarea is mainly concentrated in the sunny, shady and semi-positivesemi-shady district. Visibility, elevation, slope, aspect, is one of theimportant factors of landscape pattern and change. At the optimization ofLandscape pattern, the emphasis should be placed on the area below theelevation of1400m and slope of10°.(4) The landscape pattern is the product of natural and human factorsworking together, the study results show that, the annual averagetemperature of Xilin River Basin region have a clear upward trendduring1960to2010, the annual precipitation have a significant downwardtrend, and the annual average aridity index showed significant decreasingtrend., the change of annual average aridity index basically consistentwith the change of landscape pattern during the study period. With theintensification of aridity, landscape pattern significantly changes in Xilin River basin, and its ecological environment tends to significantlydeterioration. It can be considered that the main natural cause of climatechange is the change of landscape pattern.In1987-2009，the growth of population has a certain degree ofvolatility in the study area，the population steady growth in1987-1999.Pressure on land Is bound to exacerbate with the increase of population,as the pastoral areas, livestock numbers have fluctuated, the animalhusbandry development trend is basically consistent with the landscapepattern change trend in the research phase.The landscape pattern changes of the research area are also closelyrelated with economic policy changes. Especially since the policy“vegetation double contraction” put in effect, the plant coverage of studyarea has been falling slightly and the ecological environment deterioratesseriously during1990-2000years.The implement of ecologicalenvironment construction project like conversion of cropland to forestand grassland, fencing grassland and shifting herds, prohibit pasture raiselivestock are played an important role to the landscape pattern changes ofstudy region between2000-2005years, which are the basic reason ofimproving ecological environment.