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

Qian Fengkui, Zhou Yang, Gu Hanlong

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

Qian Fengkui, Zhou Yang, Gu Hanlong※

(1.110161,;2.,110161,)

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 quantitativeresearch 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.

farms; agriculture; grains; basic farmland protection; dynamic evolution; China

0 Introduction

Farmland is an important strategic resource in the world and closely related to food security and economic development, especially in China, which faces a strong contradiction between its large number of people and limited farmland area[1-3]. To obtain accurate data on the farmland area, the Chinese government carried out the first national land survey from 1984 to 1996 and estimated a farmland area of 130.03 million hm2in 1997. Subsequently, the second national land survey covering from 2007 to 2009 estimated a farmland area of 135.39 million hm2. Although there were data errors and inconsistencies in the survey results owning to different analytical methods, personnel training, and human intervention, the published land data are useful for land-use planning, land consolidation, land classification, and the farmland balance system. Since the first national land-use survey, a national land survey has been and will be conducted in each decade to measure the progressive increase in capital and advanced technologies investments to obtain accurate land-use data. In addition to information on farmland quantity, farmland quality has also been a concern of the Chinese government since the agricultural land classification project was initiated in 2005 and updated every 6 years[4-5]. By 2016, the area of farmland above the average grade of 9.96 was approximately 39.82 million hm2, covering merely 29.4% of the total farmland. In comparison, the area of medium to low-quality farmland was 95.57 million hm2and accounted for nearly 70.6% of the total farmland. Therefore, the limited farmland area with a large proportion being low quality implies that China must implement the strictest basic farmland regulations. In 1988, the Chinese government put forward a basic farmland policy requiring that no less than 80% of the total farmland have the best soil quality, adequate irrigation, gentle topography, and intensive farm management within each land-use planning period. Thus far, basic farmland protection has experienced 30 years of development history and has provided thresholds to guarantee both farmland and food security[6-7]. Together with the permanent basic farmland research conducted in 2016, the basic farmland and permanent basic farmland research, which attracted numerous scholars and also achieved notable research achievements over 30 years, has acquired important status in farmland protection and utilization[8-10]. The research has provided scientific guidance and references for farmland management and for implementing revolutionary ideas, especially in the methods and models constructed, policies implemented and practical applications[7,11-12]. Agriculture land conversion is common in urbanization and industrialization and shows different features in developed and developing countries. Agricultural land loss is more intense in developing countries experiencing rapid economic growth and a transition in their economic structure[13]. The rate of agriculture land conversion was only 17 hm2per day in the Netherlands from 1996 to 2000, while the rate reached 114 hm2per day in Germany in 2006. The aforementioned agriculture land conversion rates are much lower than those in China and Indonesia, which were 802 hm2per day in 2004 and 514 hm2per day from 2000 to 2002, respectively[14-15].

However, there is no systematic review of the research literature that summarizes the research achievements or explores the development trends of basic farmland research. Such a review would not only help with understanding the progress and focus of basic farmland research but would also contribute to producing new research findings for future basic farmland protection. To clearly illustrate the research rules of basic farmland subjects and contents in different remarkable stages, the visual document analysis software named CiteSpace was used to analyze the basic farmland research development and trends. Based on the review of 1 338 articles collected from the Chinese National Knowledge Infrastructure (CNKI), the specific objectives of this study are the following: i) summarize the progress of basic farmland research and analyze the research trends over 30 years (1988-2017), ii) illustrate the detailed basic farmland research focus and contents for each decade (1988-1997, 1998-2007, and 2008-2017), iii) discuss the principal challenges in the research and identify future basic farmland research priorities.

1 Materials and methods

1.1 Methods

CiteSpace is an analysis software used to address questions about a knowledge domain[16]. The knowledge domain is a broadly-defined concept that covers a scientific field, a research area, or a scientific discipline[17]. By processing the data from the Chinese National Knowledge Infrastructure (CNKI), CiteSpace can identify the focus of each research node, draw a knowledge map showing the research progress and tendency in specific periods, and illustrate the evolutionary process of the research in detail via information visualization analysis. The co-occurrence network of keywords generated by CiteSpace can be implemented to analyze hot topics in the basic farmland research field. Each node represents a keyword in the cluster map and each link between two nodes illustrates that the two keywords are present in the same article. The weight of each linked line represents the frequency of the coexistence of two keywords. The nodes represent various keywords, and the radius of each node represents the overall frequency of each keyword and the number of articles that contain the keywords of interest. The annual ring for each node represents the evolution of basic farmland research in various research stages. The width of each ring represents the frequency with which a keyword occurs in a specific year. The inner rings represent earlier years and the outer rings represent the most recent years. Additionally, if a ring of a certain node (e.g., the node “the permanent basic farmland”) is red, it means there was a burst in a certain time period, indicating that this node represents a research frontier[18].

In the present study, the progress of basic farmland research from 1988 to 2017 was comprehensively analyzed by using CiteSpace. This methodology can be used to identify and form basic farmland research groupings or clusters for different periods, which can be used to infer and obtain more specific information through clustering, labeling, and exploring the research focus. Then, the cluster analysis for each decade (e.g., from 1988 to 1997, from 1998 to 2007 and from 2008 to 2017, respectively) is processed in detail to illustrate the research focus and evolutionary rules of the three stages in a timeline view and as a burst detection function with CiteSpace. This strategy contributes to summarizing the good knowledge of the concentrated fields, critical issues, and emergency problems of basic farmland research and providing advice for scientific research and practical work on farmland protection.

1.2 Data Sources

The literature data, including the data from Chinese core journals, Chinese Social Sciences Citation Index (CSSCI) journals, and Engineering Index (EI) journals, were collected from the Chinese National Knowledge Infrastructure (CNKI). The primary selected and searched subject term and title was “the basic farmland” published over 30 years from 1988 to 2017. This time period was consistent with the 30 years of history of farmland protection in China, particularly from the first land administration law promulgated in 1986, and the first basic farmland zone demarcated in 1988. Thus, there are 1 338 articles published on the subject of basic farmland, and three vigorous research periods were 1994, 2004, and 2012, as evidenced by the rapidly increased research achievements. In the early stages, with the first basic farmland protection regulations promulgated from 1988 to 1994, more research focused on the definition of basic farmland and the management of middle-low yield farmland. After 2004, the research was mainly concentrated on the evaluation, construction, and demarcation of basic farmland in 1 083 articles, accounting for 78.0% of the total literature on basic farmland. The basic farmland research field has attracted increasingly more interest from Chinese scholars due to its unique Chinese characteristics. Therefore, establishing a cluster mapping and a timeline view of the basic farmland research knowledge may be an efficient way to discuss and explore the current progress and future trends of basic farmland research through a literature analysis using CiteSpace.

2 Results

2.1 Research progress and trends from 1988 to 2017

Fig.1 displays the four research clusters with a timeline description to demonstrate the focus and contents of basic farmland research in each domain’s research period according to the basic farmland research keywords. The first research cluster was related to basic farmland protection, the second research cluster paid attention to basic farmland evaluation, the third research cluster was concerned with basic farmland and permanent basic farmland demarcation, and the fourth research cluster concentrated on basic farmland construction, especially high standard basic farmland construction.

2.1.1 The basic farmland protection research cluster

In the basic farmland protection research cluster, there were three research foci and contents. The first cluster reflected the quantity and quality of basic farmland and environmental protection with the main keywords of “farmland quantity”, “land survey”, “farmland red line”, “farmland quality”, “farmland classification”, “farmland security”, “trinity protection”, etc. Especially after the protection regulations of basic farmland that were approved and implemented in 1994, some scholars carried out more research on the demarcation of basic farmland protection zones to guarantee a sufficient and stable quantity of basic farmland to meet food needs[19-20]. Then, basic farmland quality research was conducted following the farmland classification regulations implemented in 2005 and the second national land survey data published in 2013. The basic farmland planning and protection rate research raised many concerns, and the triune protection of the quantity and quality of farmland and the ecological environment was put forward and became important theoretical guidance for farmland protection[21].

Fig.1 4 clusters of basic farmland research during 30 years (1988-2017)

The second cluster displayed the basic farmland protection policy research with the main keywords of “land plan regulation”, “land-use control”, “policy system”, “institutional innovation”, etc. The role of a land-use plan and control should be important and strictly enforced in basic farmland protection[22-24]. In the basic farmland institutional innovation research, the protection rate and responsibility were found to be associated with economic compensation from one city to another city; i.e., cities with abundant farmland seek more protection for others with limited farmland to not only relieve and balance the pressure from basic farmland protection but also contribute to enhanced financial revenue to protect basic farmland efficiently[25].

The third cluster referred to the monitoring of basic farmland protection with the main keywords of “dynamic monitoring”, “Geographic Information System (GIS)”, “Remote Sensing (RS)”, “early warning system”, etc. The establishment of a basic farmland dynamic monitoring system combined with advanced technologies such as GIS, RS, and Global Information System (GPS) to achieve precise management was highlighted. On this basis, the farmland information extraction and the basic farmland protection mapping, farmland use change, and network database were easy to operate at any time and any place. Hence, integrating the dynamic monitoring system and prewarning system scientifically was imperative for the triune protection of the quantity, quality, and ecological conditions of basic farmland[26].

2.1.2 The research cluster of basic farmland evaluation

First, basic farmland evaluation concentrated on the evaluation of basic farmland suitability and calculating the basic farmland evaluation index and criteria for completeness and accuracy with the research keywords of “land evaluation”, “potentiality analysis”, “suitability assessment”, “evaluation system”, etc. Aiming at the absence of quantitative evaluation standards for basic farmland demarcation, constructing comprehensive evaluation systems with farmland quality, utilization, and ecological and social-economic conditions were put forward to guide basic farmland demarcation and protection[27-28].

Second, the basic farmland quality evaluation research was mainly found with the research keywords of “farmland classification”, “farmland quality, “grade conversion”, etc. Particularly, after the farmland classification results were published and proposed to be implemented in basic farmland protection, basic farmland quality was found to feature universal characteristics of soil quality and environmental site conditions, which contributed to demarcating and protecting basic farmland more reasonably and practically[29-30].

2.1.3 The research cluster of permanent basic farmland demarcation

The concept of permanent basic farmland was developed to implement special and strict protection of farmland, especially in the outskirts of urban areas and near traffic routes. The theory on the demarcation and methods that establish permanent basic farmland were major two research fields. The research keywords of “permanent basic farmland”, “Land Evaluation and Site Assessment (LESA) system”, “high standard”, “informational technology”, etc., were used to assess the theoretical research on permanent basic farmland demarcation, which could provide a theoretical basis for cognition and practice in this field. Under the theoretical guidance of the LESA, high quality and stable environmental site conditions were found to be the main required indicators, both of which were essential and complementary to each other to guarantee the permanent stability of basic farmland[31-32]. The multifunction of farmland, including grain production, ecological and cultural functions, construction supporting function, etc., and various characteristics, such as large area, high yield, good quality, high degree of continuity, etc., were considered to be fundamental for permanent basic farmland. Especially, the farmland with good location conditions, such as farmlands near the main road and in periurban areas, should be given demarcation priority for permanent basic farmland zones.

The research field of permanent basic farmland demarcation methods covered the main keywords of “GIS”, “farmland classification technology”, “land survey” and “land consolidation”, etc., all of which were practical applications of technical regulations of farmland protection and represented the database and research results authoritatively. Particularly, combined with farmland classification results, the GIS technology was used widely and popularly to enhance the permanent basic farmland demarcation results reasonably and scientifically with comprehensive evaluation indicators. Aiming to guarantee farmland quality and quantity to protect food security, farmland production capacity, and spatial clustering analysis could also be used as the permanent basic farmland demarcation and adjustment methods[33].

2.1.4 The research cluster of high standard basic farmland construction

The research of high standard basic farmland construction highly emphasized practical applications in construction zoning, construction timing sequences, and construction standards and models at the national, provincial, and county levels.

The main research keywords of “regional demarcation”, “spatial orientation”, “construction subregion”, “basic farmland layout”, etc., were present in the research field of high standard basic farmland construction zoning. The evaluation indicators of farmland natural conditions, infrastructure, engineering conditions, social and economic acceptability were applied for defining the high standard basic farmland construction conditions and zoning research with a multicriteria decision model, step discriminant analysis, spatial autocorrelation analysis, and limiting factors analysis. With regard to ecological niche theory, a niche-fitness model was constructed to carry out the potential zoning research of high standard basic farmland construction[34-35].

In the timing sequence research of high standard basic farmland construction, the main research keywords of “priority rating”, “priority ranking”, “scheduling”, “comprehensive assessment”, etc., were adopted frequently to determine construction feasibility and acceptability. To meet the essential conditions demands of high standard basic farmland, feasibility assessments were carried out using quadrant analysis, the LESA model, raster data analysis, the ideal point of entropy weighting, etc., to determine the timing sequence of high standard basic farmland construction[36].

As to the research on the criteria and models of high standard basic farmland construction, the main keywords of “construction criteria”, “construction models”, “land consolidation”, “stakeholder willing”, etc., often appeared, following the technical regulations of high standard basic farmland construction. According to the regional different features of farmland quality and utilization conditions, the specific construction criteria and models were raised by adjusting measures to local conditions, including the dry farming areas in northern China, the hilly areas in southwestern China, and the cold black soil area in northeast China.

2.2 Research focus and contents in each decade (1988－1997, 1998－2007, and 2008－2017)

2.2.1 Research focus and contents from 1988 to 1997

In this initial research stage (Fig.2), the research contents and methods were simple, only qualitative research referring to land management laws and farmland regulations, which was reflected theoretically by two research clusters of the basic farmland protection zone demarcation and construction.

Fig.2 2 clusters of basic farmland research during the first 10 years (1988-1997)

Because of the different viewpoints and understandings of basic farmland protection and zoning, the contents and methods for demarcating basic farmland were adopted according to the different conditions in the initial research, and the first and primary goal of basic farmland demarcation was to meet the demand for agricultural products due to rapid population growth. In the theoretical analysis, the farmland with good and high quality, especially the farmland distributed in suburbs and on both sides of the main roads, should be designated as the basic farmland protection areas. Both economic developments with nonagricultural land and urban construction should be considered to coordinate with basic farmland zoning harmoniously[19].

In the basic farmland zoning construction research, the focus and contents were mainly concentrated on the middle-low yield farmland transformation and infrastructure construction to increase grain production. Strengthening the planning efforts and increasing the capital and technology input were primary conditions and efficient ways to construct and zone basic farmland[37]. In addition, building terraces on sloped land to control water and soil loss, constructing water diversion and storage projects to enhance drought and flood resistance, establishing a compensation system for farmland quality to improve soil fertility, etc., with biological and engineering measures were proposed for basic farmland zone construction.

2.2.2 Research focus and contents from 1998 to 2007

Following the land management law and the basic farmland protection regulation amendments in 1998 and 1999, respectively, basic farmland protection was required as an essential for overall land-use planning on the national, provincial, and county levels. The research focus and contents in this stage were more abundant and extensive than those in the initial stage, and attention was paid to two research clusters (Fig.3) named the basic farmland protection and demarcation research and the coordination research with economic development pressure.

Fig.3 2 clusters of basic farmland research during the second 10 years (1998-2007)

The protection and demarcation mechanism research was carried out from the perspectives of farmland productivity, land planning, farmland quality protection, legal institutions, etc., which contribute to the development of basic farmland protection theory and methods[38]. In addition, the information system should be improved, particularly in motoring farmland quality in the basic farmland protection zone, and a comprehensive supporting technical system to increase grain yields using cultivation techniques, drought resistance, and water-saving techniques should also be established[39].

The coordination research between economic development and basic farmland protection had caused concerns and discussion, especially in 2002 and 2003, 2.03 and 2.88 million hm2of farmland covering good quality areas were eliminated and occupied, respectively. Therefore, in urban development planning, the multifunction of basic farmland should be enhanced and play important roles in demarcating the basic farmland layout, which can contribute to limiting rapid urban expansion and protecting good quality farmland from being occupied and destroyed[40]. In regions of rapid economic development, the institutional innovation of transferring the basic farmland protection rate and responsibility to other regions was put forward; this transfer not only can relieve and balance the basic farmland protection pressure but can also contribute higher financial revenue to protect basic farmland with increasingly greater efficiency[41]. In traditional mining regions where the land was particularly destroyed and polluted by mining with sources of land subsidence and ecological risk, the application research of ecological restoration technology was very essential and significant for basic farmland protection.

2.2.3 Research focus and contents from 2008 to 2017

Following the second national land survey and second overall land-use planning, the basic farmland research focus and contents in this stage became more diversified and practical than in the previous stages, with 103 million hm2of permanent basic farmland and 53 million hm2of high standard basic farmland expected to be constructed in the whole country by 2020. In this period, the research theory and methods used to guide practice were relatively more perfected and mature and were represented in the three research clusters (Fig.4) of the basic farmland protection, permanent basic farmland evaluation and demarcation, and high standard basic farmland construction research.

Fig.4 3 clusters of basic farmland research during the third 10 years (2008-2017)

Farmland quality was the first main research focus and content in the basic farmland protection research cluster. Especially after the results of farmland fertility evaluations and farmland classifications from the most recent 10 years were published, the criteria for farmland quality and the evaluation index system were deemed to be defined and established with increasingly perfection and abundance[42]. In addition, enhancing the regulation of the land-use control system was also an efficient way to protect the quantity and quality of basic farmland. The establishment of basic farmland protection policies and laws was also necessary and feasible through the basic farmland planning, utilization, classification, motoring, reward, and punishment mechanism[25]. This enhanced the applications of “3S” (GIS, RS, and GPS) technologies aimed at accomplishing the transformation from traditional to digital informatization management for basic farmland protection.

The permanent basic farmland demarcation, which was based on the accurate evaluation results, raised concerns on the establishment of evaluation systems and methods in the permanent basic farmland research cluster[43]. Referring to the traditional land evaluation method, a comprehensive assessment system was built using the characteristics of farmland quality, utilization conditions, ecological conditions, etc. to carry out the suitability assessment of permanent basic farmland. In addition, the LESA system was also put forward to be applied in stability and sustainability evaluations of permanent basic farmland[44].

In the research cluster of high standard basic farmland construction, the construction conditions, incorporating natural conditions, infrastructure and engineering conditions, and social and economic acceptability, were the primary and key research foci and contents to guide the practice and application scientifically[45]. Furthermore, the construction zoning, timing sequence, and models of high standard basic farmland were other main clusters of research carried out using various methods and had important guiding significance for high standard basic farmland construction practice.

3 Discussion

3.1 Extension of basic farmland connotation

From the analysis of basic farmland research clusters through the most recent 30 years, the connotation of basic farmland has changed in various ways and extended continuously as different concepts of the functions and characteristics have been developed and improved in different research stages. In the initial stage, the basic farmland connotation only referred to the farmland with stable grain yields, despite whether it was influenced by drought or flood. Following the basic farmland regulations implemented and amended, basic farmland was not permitted to be occupied or changed for other land uses without overall land-use planning approval[46]. Permanent basic farmland has been promoted to be a national strategy in recent years and defined as special basic farmland with characteristics of high soil quality, contiguous and large scale areas, and permanent and stable utilization. Subsequently, high standard basic farmland was raised to guarantee permanent basic farmland construction with supporting facilities, high and stable yields, good ecological environments, and strong disaster resistance through land consolidation. The extension of the connotation of basic farmland has been adapted to modern agriculture development and management, representing its national strategic status and satisfying the population and socioeconomic demands.

3.2 Different features in basic farmland spatiotemporal research

The research cluster of basic farmland protection is the dominant and popular focus and content of qualitative to quantitative research in each stage over the recent 30 years. Initially, basic farmland protection emphasized basic farmland zoning through national farmland protection regulations using qualitative methods, which aimed to guarantee the quantity of basic farmland and enforce the regulations of land-use plans. Subsequently, basic farmland protection included both the quality and quantity on the basis of farmland classification, land-use plans, land information systems, land policy, and regulations through quantitative and qualitative analysis. Currently, basic farmland protection includes the triune protection of the quality, quantity, and ecological conditions of basic farmland, which also reflects the national strategic demand for farmland protection in the new period.

In the different scales of basic farmland research, the features are usually common on the national, provincial, and county levels and concentrate in the basic farmland planning layout, adjustment, and allocation. Especially, the quantitative index of basic farmland protection is determined by the national and provincial land administration departments; and the location of basic farmland is determined by the various features of the farmland quality and ecological conditions on the county scale. Therefore, the conditions and indicators for basic farmland and permanent basic farmland demarcation showed significant differences between metropolitan areas with rapid economic development and ecology protection zones with good environmental site conditions. High standard basic farmland construction also showed different characteristics, particularly in construction zoning, time series, and models on spatial scales, such as those for plain and hilly areas, major and nonmajor grain-producing areas, etc.

3.3 Exterior and interior influencing factors

The exterior policy and environment are the primary factors that influence the development of basic farmland research. As stricter basic farmland protection systems have been promulgated due to rapid urbanization and industrial pressures, the initial objective of the policies was to guarantee the quantity of basic farmland and it subsequently changed to ensure the quantity, quality, and ecological conditions of basic farmland. Especially, the first (1985-2000), second (1996-2010), and third (2005-2020) national overall land-use plans were implemented to maintain the farmland red line of 120 million hm2and the dynamic equilibrium of the total amount of high-quality farmland, these strict land-use plan policies were in accordance with the fundamental principles of basic farmland protection, economic development, and intensive land-use. The basic farmland protection and demarcation research has gradually become the focus.

The interior factors are related to declining farmland quality and ecological conditions, which threaten food security and sustainable development and have aroused considerable public concern. Therefore, the central government put forward a series of policies and measures to improve the quality and ecological conditions of farmland (e.g., formula fertilization via soil testing, farmland fertility evaluation, and high-standard farmland construction). The basic farmland evaluation and construction research raised concerns and proposed various evaluation systems and construction standards at different scales.

3.4 General problems of basic farmland research

In general, although basic farmland research has achieved some fundamental results and effects that guided basic farmland practice and management in the most recent 30 years, some certain research problems remain to be emphasized and resolved in future research. The first problem is related to the evaluation indices that are still indistinct and not uniform across different scales of research. Although the regulations and results of farmland classification had been implemented and applied in research practice, the selected evaluation indices cannot reflect the difference and features in the various basic farmland research regions, and the coordination relations between the quality and site conditions of farmland are also not considered to guarantee the permanent and stable demarcation of basic farmland in the future.

The second concerned problem refers to the funding sources for basic farmland research including the Natural Science Foundation of China (NSFC), the National Social Sciences Fund (NSSF), local government projects, etc. and the multidisciplinary collaboration of geography, management,natural resources and environmental sciences. However, only 25.32% of the research found in the analysis of the published articles in the most recent 30 years was funded by national projects, and few research results were funded by local government projects, indicating that the local government paid little attention to the basic theory and methods research of basic farmland. Therefore, it is necessary to enhance and enlarge the funding sources from both national and local governments to generate important achievements in the basic farmland protection theory research and practice.

4 Conclusions

This study constructed four cluster maps for 1 338 articles published in the recent 30 years from 1988 to 2017 using the visual document analysis software CiteSpace. The research focus and contents in basic farmland evaluation, demarcation, and construction are clearly illustrated and discussed. The data support the following conclusions:

1) The results showed that the connotation extended continuously from basic farmland to permanent basic farmland and high standard basic farmland as society and technology developed, different features were represented in the spatiotemporal research of basic farmland, and the triune protection of the quality, quantity, and ecological conditions of farmland was presented in basic farmland protection.

2) Additionally, one concerning research problem is how to construct uniform evaluation indices for basic farmland protection or demarcation, for which not only farmland quality but also site conditions must be considered and simultaneously coordinated. The other problem is the necessity of increasing funding resources through various channels to support basic farmland protection theory research and practice.

3) Since basic farmland protection has been upgraded to a national strategy, the fact that the theoretical research of basic farmland lags behind practical exploration must be changed. In future research, permanent basic farmland demarcation and high standard basic farmland construction and the contents of their special functions that can be used to prevent urban sprawl and guarantee food security will be the research foci. In addition, the basic theory supporting the research should be enhanced and improved using evaluation indices and methods on different scales considering not only regional characteristics but also a uniform evaluation system in practice.

4) Furthermore, the basic farmland protection policy and institutional research is also essential and should keep pace with the demands of social and economic development to ensure its permanent stability. Therefore, multidisciplinary cooperation partnerships (e.g., soil sciences, geography, management, and environmental sciences) should be strengthened to resolve the current scientific problems and explore frontier research in the basic farmland protection research field.

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1988—2017年中国基本农田保护研究动态演化分析

钱凤魁，周 阳，顾汉龙※

（1. 沈阳农业大学土地与环境学院，沈阳 110161； 2. 土肥资源高效利用国家工程实验室，沈阳 110161）

为全面探讨基本农田领域研究态势，该研究采用CiteSpace软件对近30年（1988—2017年）发表的基本农田主题研究领域1 338篇文献进行了可视化分析。研究结果表明：基本农田主题研究集中分布在保护、评价、划定和建设4个聚类组团。其中，基本农田保护领域重点突出了对基本农田数量、质量和生态环境的保护研究态势，基本农田评价领域强调结合现代信息技术的基本农田评价体系和评价方法模型的构建，基本农田划定研究重点分析了基本农田保护区和永久基本农田划定的理论和实践发展态势，基本农田建设领域重点研究了不同尺度下高标准基本农田建设时序、分区、标准和模式。近30年基本农田主题领域研究态势表明，基本农田内涵、评价和划定理论和方法在不断丰富和完善，基本农田研究已成为耕地保护领域关注的热点，建议加强该领域多学科协同研究和相关基金项目支持。

农田；农业；粮食；基本农田保护；动态演化；中国

Qian Fengkui, Zhou Yang, Gu Hanlong. Dynamic evolution analysis of basic farmland protection research in China from 1988 to 2017[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(19):272-282.doi：10.11975/j.issn.1002-6819.2020.19.031 http://www.tcsae.org

钱凤魁，周阳，顾汉龙. 1988—2017年中国基本农田保护研究动态演化分析[J]. 农业工程学报，2020，36(19)：272-282. (in English with Chinese abstract) doi：10.11975/j.issn.1002-6819.2020.19.031 http://www.tcsae.org

date：2020-03-20

date：2020-08-31

National Natural Science Foundation of China (41671329); Liaoning Social Science Planning Fund (L18BGL005); China Scholarship Council (201808210445)

Qian Fengkui, PhD, Professor, research interests: farmland evaluation and protection. Email:fkqian@163.com

※Corresponding author：Gu Hanlong, PhD, Lecturer, research interest: land use and management. Email: allenguhan@126.com

10.11975/j.issn.1002-6819.2020.19.031

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1002-6819(2020)-19-0272-11