## 3 Results
### Different Land Use Transitions  
From Figure 5, it can be observed that during the period of 2000-2020, a significant amount of farmland was converted to built-up areas and water, with a portion also being converted to forest land. This indicates that with the rapid advancement of urbanization, a significant amount of farmland has been converted into urban infrastructure and built-up areas. Conversions of water areas primarily targeted farmland and built-up areas. This phenomenon may be related to regional policies, such as the \"Yangtze River-to-Tai Lake\" water diversion project, and the subsequent urban development, which have led to increased water resource utilization. Forests and grasslands exhibited an overall declining trend between 2000 and 2020, with some areas being converted into farmland, unused land, or built-up areas. This reflects the impact of land development pressures on the ecosystem. Such changes may lead to a reduction in regional carbon sequestration capacity and loss of biodiversity. Therefore, in future regional spatial planning, it is essential to prioritize the protection and restoration of ecological land to ensure sustainable development in the region. Figure 4: Area and proportion of land use types from 2000 to 2020. From the perspective of single land use dynamics (Table 6), between 2000 and 2020, the dynamic degrees of farmland, forest land, grassland, and water bodies were all negative, indicating a continuous reduction in the area of these four land use types and a negative directional change trend. The single dynamic degree of grassland was the lowest, reaching \(-3.72\%\), suggesting that a substantial amount of grassland rapidly transitioned to other land use types. It may be associated with regional urban expansion, agricultural reclamation, and ecological degradation, leading to a significant reduction in grassland area across the study area, resulting in the destruction of grassland ecosystems, a decline in biodiversity, and an impact on ecological functions. This reflects the insufficient protection of grassland resources in the rapidly developing the Southern Jiangsu urban agglomeration region. The single dynamic degrees of unused land and built-up land (13.12%, 7.08%) were positive over the 20 years, and their values were significantly greater than those of other land types, especially during the period from 2000 to 2010, where the single dynamic degree of built-up land was 8.31%, indicating an acceleration of urbanization and industrialization in the study area, which led to the conversion of large areas of farmland, forests, grasslands, and other land types into urban construction land. During this period, the single dynamic degree of unused land reached 24.8%, reflecting the potential inefficiency in land development. The period from 2000 to 2010 was the most intense for land use changes: the dynamic degrees of grassland, unused land, and built-up land all exhibited significant changes, indicating that the region was in a phase of rapid expansion. The dynamic degree of built-up land reached 8.31%, reflecting the peak of urbanization and development intensity. Between 2010 and 2020, land use changes slowed down, but the trend of urban expansion continued: the dynamic degree of grassland shifted from positive to negative (\(-9.68\%\)), indicating that grassland area continued to decrease during this period, highlighting growing concerns about ecological protection; the dynamic degree of built-up land decreased to 3.20%, and although the growth rate slowed, it still indicated that the  
Figure 5: Sankey diagram of land use type area transfer from 2000 to 2010 to 2020.  
urbanization process had not stalled. Considering the comprehensive land use dynamics, from 2000 to 2020, the comprehensive land use dynamic degrees in the Southern Jiangsu urban agglomeration region were all positive, with a land use comprehensive dynamic degree of 1.33%, indicating a relatively fast pace of land use change and a significant comprehensive impact of human activities on natural ecosystems.