Research On Vegetation Coverage And Carbon Storage In Engebei Ecological Demonstration Area Based On Multi-source Remote Sensing

The change of carbon storage in terrestrial ecosystem is closely related to the natural environmental impact of vegetation and human disturbance.The vegetation coverage also reflects the natural environmental impacts and human activities such as photosynthesis,death and harvest of vegetation.Studying the changes of vegetation coverage and carbon storage will provide important information for ecosystem optimization,provide scientific basis for mitigating climate change,and lay a foundation for peak carbon dioxide emissions and carbon neutrality.The Engebei ecological demonstration area is located in the northern edge of the central Kubuqi Desert,and its ecological status is not only related to the development of this area,but also to the ecological security of North China,Northwest China and even the whole country.Therefore,it is very important to know the vegetation coverage and carbon storage in this area.Taking Landsat,Sentinel-2A remote sensing data and field sample data as data sources,this thesis studied the vegetation coverage and carbon storage in Engebei ecological demonstration area since ecological construction.The main contents include the investigation and processing of measured data in sample plots,the pretreatment of two kinds of remote sensing image data,the consistent processing and calculation of vegetation coverage,the extraction of remote sensing features,the selection of modeling factors,and the research of remote sensing estimation model method of carbon storage.The most suitable model and image for remote sensing estimation of carbon storage in the study area are obtained,and the carbon storage in the study area over the years is estimated by using the relationship between vegetation coverage and carbon storage.The main results are as follows:(1)The vegetation coverage of the study area is calculated by pixel dichotomy model from Landsat 8 OLI and Sentinel-2A remote sensing images in the same period.The results show that the vegetation coverage calculated by satellite images of different sensors is different at the same time.Therefore,the vegetation coverage calculated by Landsat remote sensing images in this study was unified.From 1991 to 2021,the vegetation coverage in the study area was between 27%and 37%,and reached the maximum value of 36.14%in 2012.In 2015,it reached the minimum value of 27.15%.According to the statistics of 16vegetation coverage grades,the vegetation coverage in the study area is generally low,and the ratio of low vegetation coverage grade to the total area of the study area is the largest.(2)In the accuracy test of the model for estimating carbon storage by remote sensing,the root mean square error of the model estimated based on Sentinel-2A image or Landsat 8OLI image is small,which meets the accuracy requirements of the model estimation.The results show that the model accuracy of Sentinel-2A satellite remote sensing image is slightly higher,which is consistent with previous research results.Therefore,it is feasible to use Sentinel-2A remote sensing image to estimate carbon storage.The fitting accuracy of Sentinel-2A image is the best,which is constructed by LASSO regression analysis,with R~2of 0.85 and RMSE of 1.62.This model and Sentinel-2A image are used to estimate the carbon storage in Engebei ecological demonstration area.(3)Quantitative analysis of vegetation coverage results and carbon storage calculation results of Sentinel-2A images was carried out,and the relationship between them was fitted.R~2 and RMSE of the model were 0.906 and 1.112,respectively.The carbon storage of the study area from 1991 to 2020 was calculated by quantitative relationship.Because the carbon storage is only calculated by vegetation coverage over the years,the calculation results of carbon storage will change with the change of vegetation coverage.In the future,Engebei ecological demonstration area should strengthen the protection and management of trees,improve the carbon sequestration capacity of vegetation,prohibit deforestation,promote the healthy development of forests,make them play the role of carbon sink,and make contributions to improving the ecological environment.