Ecological Risk Assessment Of Oasis Based On Land Use And Landscape Pattern Changes

Oasis is a complex ecosystem,the oasis is a driving force development in arid areas,The oasis ecological imbalance will lead to desertification,so it is necessary to assess ecological risk in oasis in order to avoid desertification trend.Turpan belongs to the typical arid continental climate,and its natural environment conditions is poor,the ecological environment is fragile and sensitive.Moreover,unreasonable human activities lead to the Aydingkol Lake drying up,ecological problems frequently happened.This paper chose the Gaochang district of Turpan as the research area,took Gaochang area 2000,2010,2015 the third phase of satellite images data as the foundation,Using the ENVI software for remote sensing image processing,selects the most fitting method to image classification,obtained the map of present land use situation in the study area,the landscape pattern index method is adopted in the study area for ecological risk assessment dynamic in study area.At last,Mapping by used the software of Arc GIS.The analysis results were as follows:1.According to the analysis of land use change,except for unused land,the research area was mainly agricultural and forest land.Accounting for more than 11%of the total area,and the grassland covered the largest area.The unused land showed a decreasing trend,decreasing by 122.68 km~2.The garden land and construction land gradually increased,and the construction land increased the most,increasing by 5.02%.Land types are frequently transformed,mainly from unused land to other land use types,mainly to grassland and cultivated land.Agricultural and forest land was also converted to unused land,except for arable land,other conversion value was less than the destination value.2.Through analyzing landscape pattern changes,It can be seen that during 2000-2015,the number of seven types of landscape patches showed a decreasing trend,and the average patch area increased.Land integrity improved.The landscape pattern of Gaochang area changed greatly,and the plaque presented a decreasing trend.The landscape pattern spreading degree and aggregation degree index showed an increasing trend.The connectivity and aggregation degree within the landscape structure increased;Shannon diversity reflected an increase in overall change.The aggregation and spreading degree of landscape structure were enhanced and the stability of landscape was weakened.3.Ecological risk:Gaochang area from 2000 to 2015 the decrease trend overall ecological risk conditions,low risk area and low risk area was increasing year by year,medium risk area,high risk area,the high risk area was a trend of decrease.High risk during 2000-2015 reduced slowly,higher risk area proportion of floating between 10%?20%,low risk area growth was slow,low risk area mainly was the water change,low risk area percentage change was not big,almost no change area from 2000 to 2010.4.Ecological risk management suggestions:the high risk and high risk area to increase vegetation coverage,reducing wind speed,windbreak and sand-fixation,strengthening the construction of ecological environment,and reduce the ecological fragile degree,reduce the ecological risk.Moderate risk management recommendations,in accordance with ecological stability,appropriate ecological environment construction.What about suggestions on the management of low-risk and low-risk areas is the administrator should increase biodiversity and strengthen the construction of regional environmental ecology.