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Studying the response relationship and spatial distribution characteristics of carbon reserve and land use change and predicting the change trend of carbon reserve caused by the change of land use type in the future can provide some reference for watershed policy formulation, land use structure adjustment, and the realization of the "two-carbon" goal. Based on the land use data from 2000, 2010, and 2020, the InVEST model was used to calculate carbon reserves and analyze the change characteristics and to simulate the land use change and its impact on carbon reserves in natural development, urban development, and ecological protection in 2030 with the help of the PLUS model. The study found that ① the main land types in the Shiyang River Basin from 2000 to 2020 were cultivated land, grassland, and unused land. The area of cultivated land, water area, and construction land in the Shiyang River Basin showed a significant increasing trend, and the construction land area increased the most. ② In the natural development scenario of 2030, cultivated land, water area, and construction all increased by 6.15%, 9.56%, and 29.9%, respectively. In the urban development scenario, the area of construction land increased the most. Compared with that in the other two scenarios, the area of forest land and grassland increased in the ecological protection scenarios. ③ The carbon reserves of the Shiyang River Basin from 2000 to 2020 showed a steady increase, with an overall increase of 0.035×10 8 t. The increased carbon reserves were mainly due to the increase in cultivated land area. ④ In 2030, the carbon reserves of the Shiyang River Basin showed an increasing trend in all three scenarios. The carbon reserves in the three scenarios were 5.65×10 8 , 5.64×10 8 ,and 5.73×10 8 t, respectively, with the largest increase in carbon reserves in the ecological conservation scenario, mainly due to the increase in grassland and woodland. The results showed that the expansion of construction land was the main cause of the loss of carbon reserves. If effective ecological protection measures are taken, the carbon reserves in the Shiyang River Basin will be improved, and the problem of the loss of carbon reserves caused by economic development can be solved.

Wetland can maintain the stability of natural ecological environment and carbon cycle. With the acceleration of urbanization and the development of marine aquaculture, the wetland ecosystem of Liaohe River estuary has been damaged to a certain extent. Based on the analysis of measured biomass of natural vegetation and normalized vegetation index extracted from remote sensing images, the biomass regression model based on remote sensing image was established. Through comparative analysis, the binomial function was the optimal model. The carbon reserves of natural vegetation in Liaohe River estuary wetland is 969 323. 100 t, which is 10% compared with the measured value of 1077 146.0181. Using remote sensing image to retrieve vegetation biomass, we can get more accurate carbon reserves of natural vegetation in Liaohe River estuary wetland. [ABSTRACT FROM AUTHOR]

Soil is a main component of the terrestrial ecosystem, and soil carbon research is significant in the carbon cycle and global change. Using the geochemical survey data from Poyang Lake in Jiangxi province and the surrounding economic zone multi-target regional, the total carbon and organic carbon from the surface, middle and deep soil in research area was studied and the organic carbon reserves and organic carbon density distribution characteristics analyzed. The results indicate that the overall carbon in the study area consists mainly of organic carbon. The reserve of organic carbon is 138 million tons and organic carbon density is 3512 t/km2 in the surface soil (0-0.2 m), 439 million tons and 11156 t/km2 in the middle soil (0-1.0 m) and 614 hundred million tons and 15617 t/km2 in the deep soil (0-1.8 m). Compared with the national agricultural geological survey data, organic carbon density of surface soil in the study area is 10.86% higher than that of the national agricultural geology survey, however, organic carbon density of middle and deep soil is close to the results of national agricultural geology. It shows that the research area has huge reserves of organic carbon. Further studies were conducted to uncover the distribution and the distribution characteristics of organic carbon in soil by using the organic carbon density and organic carbon reserves for different soil types, different land utilization types, different geomorphic units and different administrative units. Research results suggest that each layers of soil possesses the same organic carbon density spatial distribution characteristics, which is closely related to the geological background and the vegetation coverage. A high value area of carbon density is located in hilly areas and mountainous regions, such as the paleozoic carbonaceous rock and coal strata from the north of Fengcheng City, the south of Gaoan City and the surrounding of Leping City. The highest organic carbon density occurred in the topsoil of Leping city. Low organic carbon density is located in lake and river valley areas. The results of this study provide reliable data for studying the carbon cycle and carbon emissions in the Jiangxi countryside.