## 4 Discussion
### Policy Interventions and Planning Pathways for Carbon Balance in Lake-Intensive Regions  
Policy interventions play a crucial role in regulating carbon budgets in lake-intensive regions. In recent years, the Dongting Lake region has mitigated the growth rate of carbon emissions by promoting green economic development, advancing industrial transformation and upgrading, and optimizing energy structure policies. For instance, the returning farmland to forest policy has significantly enhanced the carbon sequestration capacity of forest ecological spaces in the Dongting Lake region. Meanwhile, low-carbon industrial transformation policies have effectively reduced carbon emission intensity in the secondary sector. However, policy effectiveness often varies across regions. For example, economically developed areas such as Changsha and Yueyang have experienced a significant slowdown in carbon budget growth due to early industrial restructuring. In contrast, Jingzhou, an agriculture-dominated region, still faces a prominent carbon deficit due to delayed policy implementation. This disparity reflects the profound impact of different socioeconomic development levels on carbon budget patterns. Therefore, policy design should emphasize regional coordination and establish cross-regional ecological compensation mechanisms to balance carbon emissions from economic development with carbon sequestration in ecological conservation [52; 53]. In this context, this study formulates a carbon balance planning pathway for the Dongting Lake region's production-living-ecological functional framework, focusing on three key priorities: economic development, farmland protection, and ecological security, specifically as follows:  
(1) For carbon reduction and sequestration in agricultural production space, water and soil resource advantages in water-land interlaced zones should be maximized to modernize irrigation areas along the lake. Based on this, the agricultural structure should shift toward a low-carbon industry model with enhanced ecological benefits. The strict protection of permanent bare farmland must be maintained. In contrast, initiatives such as returning farmland to lakes, afforestation, and reforestation should be promoted to develop waterfront agricultural systems that align with the carrying capacity of watershed resources and the environment. For example, in Jingzhou, a waterfront farmland-dominated region, efforts should be intensified to return farmland to lakes and adjust the agricultural structure, emphasizing lakeside green agriculture, eco-friendly circular farming systems, and enhanced agricultural carbon sequestration. As a key agricultural production area, Changde should strengthen farmland ecological protection, promote green agricultural technologies, advance smart agriculture, and maximize agricultural carbon sequestration benefits. (2) For carbon reduction in urban-rural living space, functional land use for industrial, residential, and public service facilities should be adjusted based on the watershed region's hydrogeographical characteristics to guide cities toward low-emission urban spatial development. Unnecessary urban development near riverbanks should be restricted, and high-carbon industries should transition to low-carbon or zero-carbon models alongside energy system innovations, promoting hydropower, hybrid wind-solar energy, and other green sources. Regarding spatial layout, high-pollution, energy-intensive industries should be relocated from waterfront areas to enhance green ecological functions along the water. As the region's industrial and technological innovation hub, Changsha should accelerate the transformation of energy-intensive industries, expand green energy adoption, promote green building and smart city initiatives, enhance low-carbon public transportation, and foster compact, low-carbon urban-rural development.