Construction And Research Of Ecological Security Evaluation System On Desert Steppe

Desert steppe located in the transition zone of desert and steppe. Because its ecologicalstructure is relatively simple, it’s susceptible to external influenced and the ability of recoveryis poor during this harsh natural environment. Under the context of global climate change, thesecurity situation of this fragile ecological system is particularly important.The desert steppe of Wulatehou Banner, which located in the Midwest of Inner Mongolia,is typical of the desert steppe zone, combined with the flag of the population density of2.6people/km2, which less human disturbance factors. The research of ecological security inthis area can explain the mechanism of how does temperature, precipitation and other keyclimate change factors effect grassland ecosystems during the context of the global climatechange. In this thesis, taking MODIS-NDVI data as data source, through forming the groundspectral modeling, considering the response of vegetation coverage and productivity tofluctuations of major climatic factors, a ecological security evaluation system were builtbased on the coalescent of vegetation coverage and productivity ecological safety assessment.For these goals, this paper measured spectral data, combined with the MODIS-NDVI datato establish a vegetation coverage——spectral model and vegetation productivity——spectralmodel, and by MODIS-NDVI inversion vegetation coverage and productivity of the year2000-2011in Wulatehou Banner. After that, through the study of the relationship betweendifferent vegetation cover distribution area with precipitation and temperature changes andproductivity levels, the use of regression analysis of different vegetation coverage,productivity levels of the distribution area with annual precipitation, growing seasonprecipitation (May to September); the annual average temperature, average temperatureresponse of the growing season (May-September) change were researched to reveal changesin the ecological security of the region and laid the foundation. Finally, by integrating theresults of the evaluation of ecological security coverage and create a new evaluation systembased on the results of the safety assessment of the ecological productivity of WulatehouBanner regional ecological security situation2000-2010were evaluated. The main findingsare as follows:(1) Wulatehou Banner2000-2011vegetation cover changes in precipitation can be found with a significant or very significant function curve fitting relationship; vegetation coverageless than10%area of the region was negatively correlated with precipitation; vegetationcover more than10%of the area of the region is positively correlated with precipitation;vegetation cover10%of the area is between the low coverage and high coverage conversionthreshold. Vegetation cover and low temperatures (average annual temperature) can not find asignificant curve, and the growing season average temperature could find a significant curve.Also, cover area of less than10%increase when the growing season temperatures down;10%area decreases when the growing season temperatures up. It showed that when precipitationincreased, areas cover less than10%will grow more than10%, while more than10%coverage area will continue to grow higher; temperatures conducive to the growth of lowvegetation coverage areas, and enable high vegetation coverage area evacuated to lowcoverage area.(2) Wulatehou Banner2000-2011vegetation productivity changes in precipitation can befound with a significant or very significant function curve fitting relationship; vegetationproductivity less than30-45g m-2area of the region was negatively correlated withprecipitation; vegetation productivity more than30-45g m-2of the area of the region ispositively correlated with precipitation; vegetation productivity30-45g m-2of the area isthe conversion threshold between the low productivity and high productivity. Vegetationproductivity and low temperatures (annual average temperature) can not find a significantcurve, and the growing season average temperature could find a significant relationship curve.Also, productivity area of less than30-45g m-2increase when the growing seasontemperatures down; more than30-45g m-2area decreases when the growing temperatures up.It showed that when precipitation increased, areas cover less than30-45g m-2will growmore than30-45g m-2, while more than30-45g m-2coverage area will continue to growhigher; temperatures conducive to the growth of low vegetation productivity areas, and enablehigh vegetation productivity area evacuated to low productivity area.(3) The ecological security situation changes in Wulatehou Banner were fluctuatingduring2000-2010.From a different point of view of ecological security level area in2000-2001, the sum of larger area was below the level of health;2002-2010the sum oflarger area was on the level of health. From the view of annual change in different ecologicalsecurity level, except for2000-2001, the area of below health grown，the situation was keep stable. Although ecological security situation was changed in fluctuation, the health area andarea better than health take63.83%through ten years average state, which means althoughecological security situation deterioration in2000-2001, the state of ecological securitysituation from2002to2010has a steady increase.