Research On The Change Of Vegetation Coverage And Carbon Storage Based On Remote Sensing

Climate Change has being not only subtly altered the function and structure of terrestrial ecosystem,but also seriously threatened the survival and health of people,which has become the biggest barrier for global sustainable development.Therefore,how to relieve and improve the vicious development of global climate has been the focus of ecological environment in 21 th century.Forest ecosystem is one of the main carbon stocks,while vegetation is the foundation of forest ecosystem and vegetation fraction directly reflects the growing state of vegetation.Hence,the investigation on the change of vegetation coverage and forest carbon storage is of great significance to the study of global climate change.The analysis of the change of the surface vegetation and forest carbon storage not only has great theoretical guidance significance practical application value to the exploration of change and the administration of forest ecosystem,but also can provide theoretical basis for the study of global terrestrial cycle and climate change.This paper chose Ganzhou City as the research area and selected the data of the remote sensing image of LANDSAT-5 TM in 1999 and 2007 as well as the remote sensing image of LANDSAT-8 OLI in 2013 as the data source.Based on ENVI 5.2,the vegetation coverage was estimated by normalized vegetation index and pixel dichotomy model.Considering the factors such as terrain,complex geomorphology and the significant change of vegetation coverage,this paper employed ARCGIS to reclassify the vegetation coverage of Ganzhou City into five grades.Therefore,the change of vegetation coverage in Ganzhou City was analyzed statistically,and the reason of the change was analyzed according to the data of temperature,annual precipitation and afforestation.Combining Ganzhou city field survey sampling data with forest resources two type survey data,this paper used the biomass source method to estimate the carbon storage of vegetation in the year of 1999,2007 and 2013 in Ganzhou City.Furthermore,considering the tree layer vegetation composition type,age grade distribution,this paper further analyzed the influencing factors contributing to carbon storage change.Finally,the changes of vegetation coverage and the characteristics of carbon storage were analyzed.The main results are as follows:(1)By means of the statistical analysis of the result of the estimation of vegetation coverage in Ganzhou City and the distribution coverage in Ganzhou city,the vegetation covereeage in Ganzhou city has steadily increased from the year of 1999 to 2013.Among them,vegetation coverage increased rapidly from 1999 to 2007 and high vegetation coverage,very high vegetation coverage was significantly increased,while medium vegetation coverage,low vegetation coverage,very low vegetation coverage area degraded to various degrees;During the period from 007 to 2013,the area of the very low and low vegetation coverage area was stable and the area of medium vegetation coverage continuedly rose to high and very high vegetation coverage area.Based on the annual average temperature,the annual average precipitation and the afforestation area in Ganzhou City,this paper analyzed the driving forces that affect the change of vegetation coverage.In the past 15 years,the annual average temperature of Ganzhou City tended to increase,while the annual precipitation tended to decrease.This change affected the growth environment of vegetation,which in turn influenced the change of vegetation coverage.After 1999,the policy of returning farmland to forests,afforestation and forest ecological vegetation protection has promoted the increase of forest land area,thus increasing the area of high vegetation coverage and extremely high vegetation coverage area.(2)Estimating the carbon storage of forest ecosystems vegetation tree vegetation in 1999,2007,and 2013 and the carbon storage of different types of tree layers,age class of trees in 2007 in Ganzhou City,this paper drew the following results: the carbon storage in 1999,2007,2013 in Ganzhou city was 3639.25×104T,5076.01×104T,5761.89×104T;Carbon storage of coniferous forest,broad-leaved forest and coniferous and broad-leaved mixed forest in 2013 was 3242.71×104T,748.11×104T,1771.07×104T;Carbon stock per unit area from high to low was 19.278 t×hm-2,25.620t×hm-2,32.713t×hm-2;Carbon stocks at different age levels from low to high was middle age forest being 3123.40×104T,young age forest being 1274.34×104T,near mature forest being 29.164×104T,mature forest being 394.05×104T,too mature forest being 43.85×104T,corresponding to the carbon density from low to high being young age forest,middle age forest,near mature forest,mature forest and too mature forest.(3)In accordance with the correlation analysis of the estimated results of vegetation coverage and carbon storage,this result showed that there was a significant correlation between the two.In line with the trend and reason of change of the two,it can been seen that the carbon storage of forest ecosystem changed with the change of vegetation coverage.Increasing the coverage of high vegetation coverage and extremely high vegetation coverage area has a significant effect on improving the carbon fixation capacity of Ganzhou forest ecosystem;meanwhile,the increase in carbon sequestration capacity also provides a better growth environment for vegetation,thereby increasing vegetation coverage.