Urbanization And Dynamic Changes Of Forest Carbon Storage In Zhuzhou

Forest carbon stocks is one of the most important indicators for measuring the vegetation status of forests and indicating changes in the ecological environment.The urbanization process will lead to the expansion of human living environment,which will also affect the living environment,living space and health of surrounding forest vegetation.Exploring the situation of urbanization and forest change is of great significance for planning the direction of urban development.Zhuzhou prefecture-level city was selected as the study area.The data used in this study include Landsat5 and Landsat8 summer and autumn remote sensing images in different years from 1999,2004,2009,and the national forest continues inventory data of Hunan Province's.Extraction and inversion methods was used to explore land use thematic information and forest carbon storage in different years.These results were analyzed by grey correlation analysis with 12 selected quantitative indicators of Zhuzhou prefecture-level city.The main conclusions are as follows:(1)A multi-scale object-oriented classification method that takes into account surface temperature was proposed to extract surface type information effectively.Surface temperature is the most important characteristic physical quantity that characterizes the change of surface processes.The surface temperature inversion by the radiation equation was used in the study for the extraction of waters,building land,and vegetation types,increasing the discrimination of these features.The classification results of the study meet the requirements of subsequent experiments that the Kappa coefficient and classification accuracy are both above 0.8 and 90%.(2)From 1999 to 2014,the area of agricultural and forestry land of counties and cities in Zhuzhou decreased significantly,with a total reduction of 53.67 thousand hectares,at the same time the construction land increased by 34.16 thousand hectares.The urban expansion was obvious,and the expansion rate was 0.53.The expansion direction of each city and county has certain regularity according to its geographical location.Economic development and population change are the main driving factors affecting the urbanization of cities and counties in Zhuzhou City from 1999 to 2014.The correlation coefficient between urban and rural residents' construction land area and Zhuzhou City's regional GDP and urban population is 0.961 and 0.938 which has clear linear relationship between them.(3)Using the improved Leave-one-out-crossing random forest(LOOC-RF)model to simulate the forest carbon stocks in Zhuzhou prefecture-level city.The coefficient of determination(R2)of the model in 1999 was 0.56,and the root mean square error(RMSE)was 0.39.The R2 of the model in 2004 was 0.54 and the RMSE was 0.57.The R2 of the model in 2009 was 0.55 and the RMSE was 0.59.The R2 of the model in 2014 was 0.58 and the RMSE was 0.63.The total amount of forest carbon storage in the four periods of the study area was 1068.11,1355.65,1923.91,and 2436.89 million tons,respectively.The total amount of forest carbon stocks in the study area has increased year by year,but the spatial distribution was not balanced.The spatial distribution of carbon storage was mainly concentrated in the southeastern part of Yanling County,the eastern part of Chaling County,the Huangfeng Bridge of Qixian County,and the northern part of Liling City.The carbon stocks of forests in the suburbs where population activities were relatively frequent have hardly increased.(4)Grey correlation method was feasible to analyze the relationship between forest carbon storage and urbanization.The ratio of construction land to cultivated land area,urban employment population and road length have highly correlations with forest carbon stocks and forest land area in Zhuzhou prefecture-level city,and these correlations were all beyond 0.90.The urban population,industrial output value and construction land area were closely related to changes in forest land area.Indicators of direct relationship with urbanization development of Zhuzhou prefecture-level were closely related to the change of forest carbon storage.The urbanization of Zhuzhou prefecture-level city has a significant impact on the forest carbon cycle in the region.