Lakes play an important role in mitigating climate change, intense human activity and climate change affect the lake's ability to sequester carbon. However, it remains unclear which play the dominant role. Identifying the decisive factors affecting lake carbon storage is the key to studying the change of lake carbon storage, which is of great significance for the protection, utilization and enhancement of carbon sequestration capacity of subsequent lakes. Our research takes the Caohai Lake to explore the impact of different influencing factors on the carbon storage.The mask extraction function of ArcGIS 10.8 was used to extract the land use data of the seven periods of Caohai Lake from 1990 to 2020s. to estimate the carbon storage of Caohai Lake In order to analyze the impacts between autochthonous and anthropogenic, especially policy factors, on the variational of carbon storage in Caohai Lake, the biomass estimation method was used during different periods from 1990 to 2020s. The results show that: (1) From 1990 to 2020, the cumulative carbon storage of Caohai Lake changed significantly, with the carbon storage of 1159933.98tC in 1995, which was the largest, but not the carbon fixation capacity of Caohai Lake in its natural state. In 2020, the carbon reserve of Caohai Lake was 313104.43 tC, with the smallest carbon reserve, which was basically the carbon fixation capacity of Caohai Lake in its natural state; (2)The overall carbon sequestration capacity of Caohai Lake is about 2.54 × 10⁸ tC in 2020; (3) The overall carbon storage of Caohai Lake has undergone a dynamic process of decreasing increasing decreasing, which is mainly affected by anthropogenic and natural factors under policy control, with the impact ratios of 91% and 9%, respectively. Accordingly, natural factors mainly affect the carbon storage of water bodies and sediments, and human factors affect the overall carbon fixation capacity of Caohai Lake. Hence, estimating the carbon reserves of Caohai Lake and analyzing the correlation of its influencing factors can clarify the main influencing factors of Caohai Lake, and propose a protection plan for Caohai Lake. This can provide a reliable data base for the utilization and protection of lakes throughout the country, provide typical case data for the country to achieve the ‘dual carbon’ goal, and ultimately achieve the dual goals of wetland protection and carbon neutrality.
 

Caohai Lake; Land use change; Carbon storage; Carbon fixation; Local policies