The Diffusion Characteristics of China's Policy of Converting Cultivated Land into Forest (Grassland)

China's Convert Cultivated Land into Forest and Grassland policy has been gradually emphasized and promoted in the context of advancing China's Western Development Program. Therefore, based on the perspective of localized practice in China, this study bridges the semantic level of information from the perspective of qualitative analysis and quantitative coding through the qualitative analysis of policy content and text similarity metrics. The study systematically reveals the diffusion characteristics of China's Convert Cultivated Land into Forest and Grassland policy with respect to spatiotemporal evolution, thematic focus, and the degree of central policy diffusion. The goals are to clarify the mechanisms of policy evolution in a long time span, to analyze the implementation effects of the policy in accordance with local conditions, and thereby to make strong contributions to policy making. The results show five important aspects of the policy diffusion. (1) The policy followed a tendency characterized by “slow-rapid-stable” stages, and its diffusion process can be summarized into four phases. (2) By integrating thematic diffusion characteristics and spatiotemporal evolution characteristics, this study reveals that the Grain for Green policy primarily exhibited a top-down “Hierarchical diffusion mode”. (3) By combining the national land cover change with the geographical distribution data of the Grain for Green policy, this study reveals that the policy has largely achieved its ecological goal of converting cultivated land. (4) Based on empirical research, this study illustrates the relationships between the number of policy issuances, the similarity between central and provincial policies, and the degree of policy diffusion, thereby enriching diffusion theory based on China′s localized practical research. (5) This study suggests that national policies appear to reduce vertical pressure, thus inspiring the innovation of regional policy. Meanwhile, efforts should focus on developing distinctive industries to promote improvements in quality and efficiency.