Dynamic Response Analysis Of Urban Forest Aboveground Carbon Storage Under Land Use Change

Land use change is an important factor affecting carbon storage in urban terrestrial ecosystem.Based on the data of land use and change in Xihu District of Hangzhou City,the data of land use and change were extracted by using the remote sensing images of 1995 / 2005 / 2010 / 2015.The carbon storage change model was established by referring to the method provided by the IPCC 2006 National greenhouse Gas Emission inventory guidelines.In order to optimize the model parameters,a stratified sampling method based on Digital Number of remote sensing image is proposed to improve the precision of sampling in urban environment.The optimized parameters were obtained by stratified sampling method of Digital Number,and the dynamic changes of aboveground carbon reserves in the West Lake region were calculated by the model.Furthermore,the dynamic response of urban forest aboveground carbon storage under land use change in the West Lake region was analyzed.Through the research,the following conclusions are drawn:(1)The changes in land use in Xihu District in the period of 1995~2015 were mainly manifested in the transformation of farmland into settlements,but the fluctuation rate of land use transfer was large,and the transfer between different regions frequently.(2)Based on the stratified sampling method of Digital Number,the carbon density of each land use in the West Lake region was estimated.The sampling accuracy of relative and simple random sampling in forest land,settlement land,farmland and wetland were increased from 87.97%?68.39%?77.22% and 71.57% to 98.84%?97.16%?97.04% and 96.84% respectively.(3)Based on the stratified sampling of Digital Number,the woodlands and settlements in the West Lake region were obtained.The average carbon density of farmland and wetland were 69.46 t C/hm2,14.94 t C/hm2,27.71 t C/hm2 and 30.46 t C/hm2 respectively.The overall average carbon density was 32.90 t C/hm2 and the sampling precision was 97.69%.(4)From 1995 to 2015,the change of carbon storage caused by land use change in the West Lake region was-111030.70 t,-77940.36 t,-50623.77 t ?-89089.40 t.The decreasing effect of land use change on carbon storage decreased slowly from 1995 to 2005,and the decreasing effect of land use change on carbon storage gradually increased from 2010 to 2015.(5)From 1995 to 2015,the vegetation carbon storage increased by 48982.30 t,62105.18 t,116749.38 t and 60597.69 t respectively every five years in the West Lake region.The overall carbon sink effect of urban forest in the West Lake region was first enhanced and then weakened.