## 3 Results
### Spatiotemporal Dynamics of Territorial Space
#### 3.1.2 Land-Use Category Conversion in Territorial Space  
Figure 4a presents the numerical characteristics of land-use category conversions in the Dongting Lake region. Over the study period, these conversions primarily involved the replacement of agricultural production space with production-living construction space (904.80 km\({}^{2}\)), the conversion of water ecological space into agricultural production space (445.02 km\({}^{2}\)), and the transition of agricultural production space into water ecological space (527.52 km\({}^{2}\)). These changes underscore the complex trade-offs between economic development, population density, and water ecological systems in lake regions. By stages as follows: (1) From 2005 to 2010, the primary land-use conversion involved agricultural production space into water ecological space, totaling 683.66 km\({}^{2}\). (2) From 2010 to 2015, the focus of land-use change shifted toward a sustained transition from agricultural production space to industrial-mining production space. (3) From 2015 to 2020, the cumulative conversion of agricultural production space into industrial-mining production space increased further, reaching 260.16 km\({}^{2}\). This trend reflects the increasing intensity of land-use category changes in the Dongting Lake region, driven by the rapid socioeconomic growth of the Yangtze River Economic Belt. During the same period, large areas of agricultural production space were converted into forest ecological space, highlighting the impact of reforestation policies in the later stages of urbanization.  
Figure 4: Category conversion of territorial space in the Dongting Lake region from 2005 to 2020 (**a**) shows the numerical matrix of category conversion; (**b**) shows the spatial distribution of category conversion.  
Figure 4b provides a more intuitive depiction of the spatial characteristics of land-use category conversions. During the study period, these changes were concentrated in three key areas: the northeastern plains of Jingzhou, the administrative regions of the five cities, and the primary lake body in western Yueyang. By stages as follows: (1) From 2005 to 2010, agricultural production space was predominantly transformed into water ecological space in regions with extensive lake and river networks, such as the central Jianghan Plain in Jingzhou and the western areas of the eastern Hubei hills. This trend was driven by converting low-lying farmland in the Jianghan Plain into aquaculture ponds, which persisted until 2010. (2) Since 2010, accelerated urbanization has intensified land-use development in major lake basins. Urban and rural living spaces expanded outward from the urban cores of the five cities, leading to the formation of industrial-mining production chains in suburban areas. This expansion often encroached on farmland and forest land with lower economic returns. (3) From 2015 to 2020, construction land continued to expand along water bodies within the administrative boundaries of each city. Meanwhile, water ecological space near lakes in Jingzhou and Yueyang was converted into agricultural production space, highlighting the ongoing severity of \"reclaiming land from lakes\" in the Dongting Lake region. Overall, water ecological space in lake regions faces dual pressures from agricultural expansion and urban construction. The conflict between carbon emissions from urban development and carbon sequestration through ecological conservation remains an ongoing challenge.