A Reaearch On The Urbanization Of Dongting Lake Area Based On Avian Habitat Protection

In the process of rapid urbanization in China,a series of ecological and environmental problems have also emerged along with the development of social economy and the improvement of people's quality of life.Dongting Lake is an important storage lake and wetland ecosystem in the Yangtze River Basin,a vital habitat for many animals and plants and one of the larger habitats for birds to spend the winter in China range.However,in the traditional development mode,a series of ecological environmental problems such as wetland area reduction,biodiversity reduction,ecological regulation function weakening appeared in this region.Urbanization is an important cause of land use structure change,and habitat occupation and landscape structure change of species is one of the most direct threats to biodiversity loss.In this paper,Dongting lake district of Hunan province was selected as the research area.By collecting data such as Landsat TM/OLI images,basic geographic digital maps,bird distribution points,climate and environmental factors of the research area from 1995 to 2015,we studied the sptio-temporal characters and the correlation between urbanization and the suitability of bird habitats.Based on these analysis result,we take the priority for ecological protection as principle,and arranged spaces for the urban sprawl in future time.The main research results and conclusions of this paper are as follows:(1)The area of construction land in the Dongting Lake District continued to increase from 1995 to 2015,but the expansion rate gradually decreased after 2005.The rapid urban expansion area gradually transitioned from the central urban area of each city and county to the county and township area,in the last 10 years,the construction land of townships is the main contributor to the increase of the area,and the traffic factor is an important factor to promote the development of townships.(2)In the 20 years,the landscape fragmentation of Dongting lake area increased,while the patch difference decreased,the proportion of landscape types get more balanced,and the landscape richness increased slightly,as the overall fragmentation of forested areas in the eastern and western parts of the study area decreased,there emerged a high value belt along the line in the central farmland and surrounding forest,however,the tidal area adjacent to water,the connection between farmland and forest,and the construction land showed an increase in fragmentation and patch type within this time.(3)During the 20 years,the area of suitable and suitable bird habitat in the lake area decreased by 144.07km2 and 51.12km2 respectively,while the area of less suitable areas increased correspondingly.The avian habitat showed a trend of transformation from high suitability level to low suitability level and from suitable state to unsuitable state.The area where adjacent to the main body of water is the main area where the suitability decreases,but under the influence of the environmental management of the lake area in the later time,the overall habitat suitability changes somewhat from the south Dongting lake area(4)The impact of urbanexpansion on avian habitat suitability is mainly reflected in the construction land in townships.The fitting curve of area change volume during each period shows that the change of construction land area in townships is positively correlated with the change of area in unsuitable areas,and negatively correlated with the change in the most suitable areas;and the correlation analysis with the change of landscape index also shows that with the increase of the overall fragmentation degree of patches under the socio-economic influence,the area unsuitable for birds in the study area also increases,however,the conclusion is alsorelated to the area size and landscape type.(5)Based on the analysis of urban expansion and bird habitat suitability mentioned above and the development suitability evaluation results of the lake district,the eight cities and counties which related with bird habitat were selected for spatial planning that takes bird habitat protection as a guideline.The determined urban space in selected city and county show two different forms,one is of continuous strip space and another is multiple discrete individuals.