Dynamic evolution analysis of basic farmland protection research in China from 1988 to 2017

In order to summarize the research achievements or explores the development trends of basic farmland research, the visual document analysis software the CiteSpace was used to carry out the aforementioned research based on the review of 1 338 articles collected from Chinese National Knowledge Infrastructure (CNKI). CiteSpace identified the focus of basic farmland research node, drew a knowledge map showing the research progress and tendency in the recent 30 years, and illustrated the evolutionary process of the research in detail via information visualization analysis. The research results showed that four research clusters were created with a timeline description, which demonstrated the focus and contents of basic farmland protection, evaluation, demarcation, and construction research. The first cluster reflected the quantity and quality of basic farmland and environmental protection. The second cluster concentrated on the evaluation of basic farmland suitability and calculating the basic farmland evaluation index and criteria for completeness and accuracy. The demarcation theory and methods of permanent basic farmland especially in the outskirts of urban areas and near traffic routes were major two research fields in the third cluster. The fourth cluster emphasized research of high standard basic farmland construction including practical applications in construction zoning, construction timing sequences, and construction standards and models at the national, provincial, and county levels. In the initial research stage from 1988 to 1997, the research contents and methods were simple and qualitative, and reflected theoretically by two research clusters of the basic farmland protection zone demarcation and construction. Following the land management law and the basic farmland protection regulation amendments, the research focus and contents from 1998 to 2007 were more abundant and extensive than those in the initial stage, and attention was paid to the basic farmland protection and demarcation research, and the coordination research with economic development pressure. Respectively, basic farmland protection was required as essential for overall land-use planning on the national, provincial, and county levels. From 2008 to 2017, the research theory and methods used to guide practice were relatively more perfected and mature and were represented in the three research clusters of the basic farmland protection, permanent basic farmland evaluation and demarcation, and high standard basic farmland construction research. The basic farmland research focus and contents became more diversified and practical than in the previous stages. From the analysis of the basic farmland research clusters through the recent 30 years, the connotation extended continuously from basic farmland to permanent basic farmland and high standard basic farmland with the development of society and technology, and different features were represented in the spatiotemporal research. Basic farmland protection encompasses the triune protection of the quantity, quality, and ecological conditions. Basic farmland demarcation has varied from frequent adjustment to permanent stability and a guaranteed certain quantity and quality of farmland. The evaluations of basic farmland have varied from qualitative to quantitative research using various methods. The exterior policy and environment improving and farmland declining are the primary factors that influence the development of basic farmland research. In general, although basic farmland research has achieved some fundamental results and effects in the recent 30 years, some certain research problems remain to be emphasized and resolved in future research. The lack of a unified evaluation system and limited funding sources are the two main problems that need to be emphasized and resolved in future basic farmland research to ensure food security and social stability. Even though basic farmland protection has been upgraded to a national strategy, theoretical research of basic farmland still lags behind practical exploration and must be changed.