# Analysis of Cultivated Land Productivity in Southern China: Stability and Drivers
## 4 Discussion
### Spatial Change in Cultivated Land Affect the Stability of Regional Cultivated Land Productivity  
Cultivated land productivity stability enables continuously high and stable yield [33; 56]. Spatiotemporally, changes in land-use structure not only reflect the dynamic expansion and contraction of various land uses in the process of regional development but also the fluctuation in its quantity, which is the foundation for exploring how land-use change responds to human activities [57]. During 2001-2022, the water and bare land areas in the Poyang Lake region decreased, whereas construction land area continuously increased, reflecting the transformation of land resource utilization in the region from a natural to an artificial state. This change is closely related to increasing human activity [58]. With population and economic growth, human demand for land resources is rising, driving significant changes in the land-use mode [58]. Natural conditions guarantee the stability of cultivated land productivity and provide favourable conditions for the efficient use of cultivated land. However, external human land-use behaviours, such as urban expansion, threaten the stability of cultivated land productivity. The central lakeside zone of the Poyang Lake region is flat, with the lake water system as the core. Cultivated land is mainly distributed in the surrounding hilly and mountainous areas. The complex topography and favourable natural conditions in these areas provide a foundation for the sustainable and stable use of cultivated land [59]. In contrast, the central plain of the Poyang Lake region, which has undergone rapid economic development, has experienced more dramatic changes in cultivated land use. The spatial stability of cultivated land in the central plain is relatively low owing to pressure from economic development, population growth, and urbanization. Rapid urban land expansion is a primary cause of the increasing instability of cultivated land in the Poyang Lake region. As urbanization accelerates, substantial high-quality cultivated land has become occupied by urban construction, especially in economically developed regions such as Nanchang and Jiutijiang [60]. This urban expansion reduces the cultivated land area and land-use efficiency, which threatens food security and the sustain ability of land use [61]. In addition, with economic development and population growth, the demand for land has surged and substantial cultivated land has been converted for commercial, industrial, and other uses. This trend was particularly prominent at the county level, further aggravating the instability of the spatial location of cultivated land [62]. To ensure food security, the government has balanced cultivated land occupation and compensation and promoted cultivated land supplementation. While these efforts have maintained the overall cultivated land area, they have caused significant spatial shifts. Newly supplemented cultivated land is often located in remote areas with poor production conditions, where it was previously of higher quality and concentrated around cities. Accordingly, to supplement the total amount of cultivated land, some bare land or other low-quality land types have been reclaimed as cultivated land [63]. The instability of the spatial location of cultivated land leads to a decline in its quality, which adversely impacts the stability of cultivated land productivity. Simultaneously, the complex interaction between farmland abandonment and reclamation has led to significant changes in the temporal and spatial patterns of cultivated land resources. Cultivated land is abandoned in some areas owing to a decline in quality and low agricultural efficiency, while in other areas, paddy field areas have increased through land development [64; 65]. Such frequent changes in the spatial position of cultivated land put pressure on its productivity. Natural geographical conditions and manmade land-use behaviour in the Poyang Lake region jointly affect the stability of cultivated land productivity.