| Regional ecological health refers to having certain stability and sustainability in the ecosystem,maintaining the diversity of internal structure and organization,and having the ability to recover from coercion.Based on the study of the concepts of land use change,potential vegetation and ecological health,this paper makes a careful summary and analysis of the research process and present situation in this field at home and abroad,and takes the Gansu section of Bailongjiang Basin as the research area,using Landsat images from 1990,2005,2012 and 2017,through the land use attitude,The land use change process of the study area during the study period was analyzed by means of land use degree,and the potential vegetation distribution in the study area was obtained based on the comprehensive sequential classification method of grassland,and the potential vegetation was converted into potential land cover,and through the comparison of potential land cover and land use,The ecological health level in Gansu section of Bailongjiang River basin was studied and analyzed in 1990-2017.The results show that:(1)During the study period,cultivated land,grassland,water,unused land appeared to decrease to varying degrees,while construction land and woodland increased.Grassland decreased the most,followed by arable land,with the least reduction of water and the largest increase in woodland.In 1990-2005,2005-2012 and 2012-2017,the comprehensive land use attitude was 0.36%,1.87% and 0.45% respectively,of which the land use change was the most intense during the 2005-2012.The comprehensive land Use index of Bailongjiang Watershed in Gansu in 1990,2005,2012 and 2017 was 214.39,214.75,214.87 and 215.30 respectively,and the land use degree was in the middle and lower level in the [100,400] interval.The land use degree of Bailongjiang Watershed in Gansu changed little in 28,and the annual rate of change of land use degree developed at a rate of 0.42%.(2)There are 12 potential vegetation types in the Bailongjiang Watershed in Gansu,which are arranged from large to small in terms of area: Micro temperate-feeble wet forests,deciduous broad-leaved forest(ⅢE),cold warm damp cold warm coniferous forest(ⅡF),lukewarm damp coniferous broad-leaved mixed forest(ⅢF),warm temperate-feeble wet forests(ⅣD),warm warm temperate-feeble dry with typical steppe(ⅣC),warm moist deciduous broad-leaved forest(ⅣE),micro temperate-feeble wet meadow steppe(ⅢD),micro warm hot dry subtropical grasses-shrub grassland(ⅤC),tundra,alpine meadow(ⅠF),micro warm moist forests(ⅤD),warm damp deciduous broad-leaved forest(ⅣF),Warm moist evergreen-deciduous broadleaf forest(ⅤE).The area of mild moist forest and deciduous forest is the largest,4965.39km2,accounting for 26.92% of the study area.The area of Warm moist evergreen-deciduous broadleaf forest is the smallest,only 10.54km2,accounting for 0.06% of the study area.(3)During the study period,the health status of Gansu section of Bailongjiang Basin was obviously different,Diebu County,Zhouqu County and Wen County were in good health,health status was mainly healthy,Wudou District and Tangchang County health condition were poor.The overall ecological health status of Bailongjiang Watershed in Gansu is in a good state of development,in 1990-2017,more than 50% of the land is in a healthy state,and the proportion of health status shows an upward trend.Judging from the change of health status,Bailongjiang Watershed in Gansu in the 1990-2017,the health status is in good condition,always in a healthy state of the largest proportion,always in an unhealthy state of the smallest proportion. |
PDF Full Text Request