Study On Ecosystem Changes And Human Disturbance Based On 3S And FRAGSTATS

The Heihe Reservoir in the county of Zhouzhi is the drinking water source of Xi’an, which is the capital city of Shaanxi province, which has been highly focused on and protected. It has profound significance on both the protection of ecological environment of the nature reserve and the protection of water source in Xi’an to research the structure of ecological systems, the quality and human disturbance on Heihe wetland nature reserve in Zhouzhi. This paper based on GPS, RS, GIS, FRAGSTATS3.3and EXCEL software, three phases (2000a,2005a,2010a) land cover data(obtained by remote sensing) of the nature reserve, surface parameter data from2000a to2010a, human activity data about2000a and2010a, detailed analysis and study the characteristics on changes of the ecological systems, evaluate qualities of the ecological systems, and build model of human disturbance in the reserve. Get the following conclusions and progress:(1) To establish the nature reserve is the weeks to Heihe wetland ecosystems turning point to the pattern of benign developmentThe main types of land cover in the reserve are forest, shrubs, cultivated land and wetland. By the data of land cover,2000-2005a:248hectares of wetland has been increased;more than200hectares of arable land has been decreased; the whole land cover types turned better; landscape complexity reduced; the potential of material, energy and information exchange between landscape heterogeneity patches became smaller.2005-2010a: Basically,the Land cover types kept a level in2005a; landscape complexity increased; the potential of material, energy and information exchange between landscape heterogeneity patches became bigger. Also found that landscape pattern indices could better reflect the trend of ecosystem succession of time and space in the short term than land cover data.(2) The quality of ecosystems in the reserve varies significantly before and after the establishment of the reserve during the10years2000-2005a:The quality of each ecosystem has a deteriorated trends, the biomass of forest ecosystem has reduced134229.51t, the proportion of which is17.97%,the area of relative biomass density of high-grade has reduce907hm; the average value of LAI(Leaf area index) of shrubs ecosystem has reduced0.05, and the coefficient of average annual variation has increased0.15, the ratio of which is2.14%; the intermediate proportion of the average of annual NPP(net primary productivity) of cultivated ecosystem has decreased59.15%, and the coefficient of average annual variation has reduced0.05; the total NPP of wetland ecosystem has increased2325t, increased2.21-fold, and the coefficient of average annual variation has increased0.01.2005-2010a:The quality of each ecosystem has improved, the biomass of forest ecosystem has increased39013.6t, the proportion of which is6.37%, the area of relative biomass density of high-grade has increased375hm2and62.5times; the area of relative biomass density of high-grade has reduce907hm2; the average value of LAI(Leaf area index) of shrubs ecosystem has rose0.6, and the coefficient of average annual variation has decreased0.15; the intermediate proportion of the average of annual NPP(net primary productivity) of cultivated ecosystem has rose6.68percent, and the coefficient of average annual variation reduced0.15, which is3times as2000-2005a’s; the total NPP of wetland ecosystem basically kept at the level of2005a, and the coefficient of average annual variation has decreased0.09.(3)The dominant factors of environmental changes in the reserve are human activities and policy factors during the10years2010a, the areas of slight and general levels of human disturbance intensity have increased1.95km2and0.15km2than2000a; the areas of obvious, clear, and severe levels have increased0.37km2,1.15km2, and0.57km2;2000-2005a (before the establishment of the reserve), the average of annual NPP presented a declined trend in92percent of the reserve, dropped by more than9gC· m-2·a-, and human activities have negative effects on the environment of the reserve;2005-2010a (after the establishment of the reserve), the average of annual NPP presented a rising trend in99percent of the reserve, increased between0and9, and the dominant factors of the environmental changes in the reserve are policy factors and human activities.