## 1 Introduction
Some studies demonstrated that local elements, including household size, cropping systems, land-use intensity, land tenure, climate change, and environmental costs, can influence grain productivity significantly [36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48]. The actual grain yields, to some extent, are determined by the quantity and quality of cultivated land, climate, agricultural technology, and cropping patterns. It is hard to accurately assess and simulate the yields. Thus, the current literature has focused on the effects of cultivated land dynamics and climate change on grain production potential (GPP) [32; 49; 50; 51]. To address these gaps, methods such as the Global Agro-Ecological Zones (FAO-GAEZ) [52; 53; 54], the Deng Genyun model [55], and the Estimation System of Agricultural Productivity (ESAP) [51; 56] were developed to calculate the GPP. Some scholars use meteorological prediction data to simulate future trends in cultivated land and GPP under different scenarios [57; 58; 59; 60]. As noted above, current studies have contributed to optimizing cultivated land use and safeguarding food security. However, the requisition-compensation of cultivated land policy requires that the area be balanced within the provincial area, while most of the previous studies, which were carried out at the national and regional levels, can hardly guide local practices, especially at the provincial scale. In fact, with the implementation of this policy, the exposed issues, notably the lack of regulation for newly reclaimed cultivated land, insufficient backup resources for cultivated land, and potential ecological risks [28], should be solved at the provincial level. Further studies are advocated on cultivated land dynamics to revamp the policies. As a vital grain production site in China, Hunan Province shows favorable agricultural production conditions in sunlight, temperature, heat, and rainfall. Impacted by the topography, grain production is mainly concentrated in northern, eastern, and southern Hunan. In these regions, the economic and climatic conditions are also relatively favorable. However, in recent years, urban and rural construction has occupied a large amount of high-quality cultivated land, and it remains unclear what the feedback of cultivated land change on grain productivity is. Considering the abovementioned facts, this study attempts to clarify how cultivated land has changed before and after the implementation of CLB, explore how and how much the change affects GPP, and answer the question of whether the current CLB policy is adequate to ensure grain production. In this paper, we discuss an influence mechanism of cultivated land change on grain production and provide an empirical analysis in Hunan Province, China. Additionally, we analyze the characteristics of cultivated land change and its influences on GPP from 1990 to 2014 using multi-sources data with a 30-m spatial resolution, and the methods of spatial statistics, land-use change indexes, the gravity center shift model, and the sensitivity model are applied in this paper. Based on the analysis, we propose response strategies of regional cultivated land protection, which could guide the planning and practice of cultivated land utilization, and provide a scientific basis and recommendations for the sustainable use of cultivated land.