Analysis On Evolution Trend And Influencing Factors Of Vegetation Coverage In Panzhihua City

Vegetation is not only the producer and stabilizer of ecosystem,but also the basic indicator of ecological environment change.Vegetation coverage is the direct reflection of vegetation change,and is also the core content of global ecosystem research on the impact of vegetation on ecosystem.Panzhihua City is a typical mineral industry city founded in 1970.The total area of Panzhihua City is 7440 Km~2.There are many kinds of animals and plants in the area,and more than 50 kinds of plants are protected by the state.With the rapid development of social economy,the consumption of minerals increases linearly,and the mining and smelting of minerals increase geometrically,which results in serious damage to the ecological environment and serious impact on land,water and biological resources,resulting in a large proportion of decline in vegetation coverage and serious damage to the regional ecological environment and biodiversity.Therefore,in order to protect the ecologica l environment and species diversity of the region,it is important to monitor the vegetation coverage in real time.The Landsat image data from 1993,1998,2003,2008,2013 and 2018 were preprocessed by ENVI software.The composite vegetation index was constructed according to the special topography and landform of the study area,and the vegetation coverage was extracted by using pixel dichotomy,regression model,spectral gradient method and forest canopy density model.The most suitable inversion study area was obtained by using pixel dichotomy.The accuracy of vegetation coverage was verified,the correlation coefficient was 0.87,and the kappa coefficient was between 0.8 and 0.83,which indicated that the experimental results were accurate and reliable.The results show that the vegetation coverage of Panzhihua City has changed to a good trend as a whole,with the vegetation coverage of 0.503 in 1993,0.538 in 1998,0.543 in 2003,0.557 in 2008,0.596 in 2013,and 0.582 in 2018,with an average growth rate of 0.015.This is in line with the unique natural conditions in Panzhihua City and the government's annual support for forest land and vegetation reclamation.Not in line.The vegetation coverage area of Panzhihua City is larger,accounting for more than 75%,mainly distributed in the north,northeast and northwest of Panzhihua City.In the main mineral areas,the buffer zone analysis(200m,500m,700m,1000m)shows a downward trend in vegetation coverage,and the closer to the mineral area,the more obvious the decline in vegetation coverage.The vegetation coverage in the range of 500 meters decreases year by year,and the decline rate increases gradually.The vegetation coverage fluctuates from 500 meters to 1000 meters.The main factors affecting vegetation coverage in Panzhihua city are sunshine time constant,the number of mining enterprises and temperature.The applied correlation analysis values are0.96,0.73 and 0.82,respectively.Humidity,rainfall and industrial technology have little influence on vegetation coverage,which are 0.48,0.35 and 0.53,respectively.