Research Status of Land Use and Carbon Emissions in China: A Visual Analysis Based on CiteSpace

Chen WU

Jiangxi Normal University, Nanchang 330000, China

Abstract In view of the reality of China’s high carbon emissions and its own development pressure, the research on land use and carbon emissions is becoming more and more important.Therefore, it is of great significance for the development of China’s low-carbon economy and related theories to have a comprehensive and clear understanding of the research on carbon emissions from land use.This paper analyzed the relevant literature on land use and carbon emissions in China in the past 19 years by using Citespace software.It summarized the research status and progress in this field, and showed the current research level of China in this field in a more concrete and vivid way through the form of knowledge graph.

Key words Land use, Carbon emission, Knowledge graph, Bibliometrics

1 Introduction

The international scientists have made new progress in studies in the natural sciences of climate changes.One of the important achievements is "land use changes lead to an increase in carbon dioxide emissions"[1].In the past 50 years, China’s land use carbon emissions have reached tens of billions of tons[2].In view of the reality of China’s high carbon emissions and its own development pressure, the research on land use and carbon emissions is becoming more and more important.Therefore, it is of great significance for the development of China’s low-carbon economy and related theories to have a comprehensive and clear understanding of the research on carbon emissions from land use.

2 Research methods and data sources

2.1 Research methodsCiteSpace used in this research is a set of software developed by Professor Chen Chaomei.Through the research object keywords, nodes, clustering and other elements in the drawn scientific map, the hot issues, institutional cooperation and research frontiers in the research field can be vividly displayed[3].In this study, we used this software to import the collected and processed sample data in a format that the software can recognize.In this way, we analyzed the node types such as authors, keywords, and emerging words of the research topic, so as to obtain a visualized information map of China’s current research status on land use and carbon emissions.

2.2 Data sourcesOn the advanced search page of China National Knowledge Infrastructure(CNKI), we took "Land Use and Carbon Emissions" as the subject, and selected "exact" in the matching method column.Then, took SCI source journals, Peking University core, CSSCI and CSCD as the source of literature, and used Chinese as the language type of the documents, and after eliminating the documents that did not meet the requirements, a total of 424 valid documents published from 2003 to 2021 were obtained.By systematically sorting and summarizing 424 documents, we are intended to show the current research status of land use and carbon emissions in China.

3 Results and analysis

3.1 Author cooperation network analysisFrom the perspective of the cooperation network(Fig.1), the clustering results of the map show that Chinese scholars cooperated closely in the research of land use and carbon emissions.Most of the articles were completed by two or more scholars.On the whole, a research team centered on Zhao Rongqin and Huang Xianjin, Chen Yinrong, Ye Changsheng, and Peng Wenfu has been formed.Among them, the Zhao Rongqin and Huang Xianjin team published a large number of papers, 13 papers, mainly from the aspects of carbon emission accounting and regional land use carbon emission.Chen Yinrong’s team published 10 papers, mainly using different models to analyze the impact of land use on carbon emissions; Peng Wenfu’s team analyzed the temporal and spatial changes of land use carbon emissions.However, it should also be noted that some authors were still in the state of independent research, and there were few connections between different academic groups, making it difficult to conduct academic exchanges across disciplines and regions from multiple perspectives.These are not conducive to the long-term development of research in this field in China, and all parties should actively strengthen exchanges and mutual learning with other authors or research institutions.

Fig.1 Author collinear map of land use and carbon emissions

3.2 Keyword time zone analysisFig.2 shows the year and frequency of each keyword first appearing in the field of land use and carbon emission research, which is of great importance for understanding the development of related research in this field.From the time zone map in the center of Fig.2, we can see that in the papers published in this field, the terms carbon emission, land use and carbon footprint were mentioned for the first time in 2003.According to the size of the keywords and their connections with other time zones, it can be seen that the subject keywords in these three aspects have laid the foundation for follow-up research in the study of land use and carbon emissions, and have always been a hot topic in follow-up research.There were fewer hot words from 2004 to 2009.On the one hand, the research was stagnant during this period, and on the other hand, it may be that the research in this period still carried on the hot topics in 2003.From 2010 to 2013, a number of new research buzzwords emerged in the literature on land use and carbon emissions, such as China, land use structure, low-carbon economy, carbon budget, and land use changes.In 2010, China started the pilot work of low-carbon industries, and incorporated emission reduction targets into the Twelfth Five-Year Plan.A series of actions in China have greatly promoted the progress of scientific research.Relevant research papers have sprung up like mushrooms, and some hot words were mentioned in the papers, which have an important impact on subsequent studies.

Fig.2 Keyword time zone map

3.3 Keyword hotspot analysisFrom Fig.3 and Table 1, it can be seen that the keywords "carbon emissions" and "land use" appeared in the literature with a relatively high frequency and strong centrality.The possible reason is that it was put forward earlier, which played a leading role in subsequent research and established the general direction of research.Besides, using "land use and carbon emissions" as the subject of literature collection may also be the reason for the highest frequency of "land use" and "carbon emissions".There were few separate keyword nodes in the figure, and the keywords were closely related, indicating that the research focus of land use and carbon emissions was relatively concentrated.In addition, keywords such as carbon footprint pressure index, carbon footprint, and land use change all had an occurrence frequency of ≥10, so they were also hot topics in this field of research.

Table 1 Ranking of high-frequency keywords in land use and carbon emission research

Fig.3 Keyword clustering map of land use and carbon emissions

3.4 Keyword burstsFrom Fig.4, we can see that China’s research frontiers on land use and carbon emissions can be clearly divided into three stages.(i)From 2003, a large number of keywords burst intensively, including "carbon footprint stress index", "Huantai County", "carbon risk",etc., indicating that some scholars have begun to conduct research in the field of carbon emissions and have made certain achievements.(ii)There were no keyword bursts from 2010 to 2018.The possible reason is that the research results in this period are the continuation research of the previous stage, and there is no horizontal divergence.(iii)In 2018, new keywords "influencing factors" burst.It can be seen from the relevant literature that at this stage, many scholars began to study the factors influencing land use and carbon emissions through empirical methods.In general, the occurrence of burst keywords in this field is characterized by a small number, low frequency, and connection with space and region.

Fig.4 Keywords with the strongest citation bursts in 2003-2021

4 Conclusions and discussion

With the aid of CiteSpace software, we analyzed the relevant literature in the field of land use and carbon emissions in terms of time, author network and keyword analysis, and presented the research topics and development overview of the literature in this field in China.We arrived at the following conclusions.

(i)In terms of time dimension, China’s land use and carbon emission research started relatively late, and has experienced a period of stagnation for nearly five years.However, with the advancement of national policies and the popularization of low-carbon concepts, more and more scholars have begun to study this field.Since 2010, the number of publications in this field has entered a new stage, and a relatively complete research network has gradually formed.

(ii)The author analysis shows that Chinese scholars present a relatively close research status in this field, and mainly focus on group cooperation, with less independent research.What’s worse, there are problems of little contact and cooperation between groups.

(iii)Keywords and burst words convey the research focus and dynamics of the field.Among them, key words such as carbon emission, land use, carbon footprint stress index, carbon footprint, land use change, and low-carbon development together constitute the main content and hot issues of research in this field.

On the whole, China’s research on land use and carbon emissions started relatively late, and the intersection with other disciplines is weak.Compared with the perspective of "land use", more literature focuses on the exploration and research of "carbon emissions".At present, relevant research still lacks in-depth research at the micro level, and the main reason may be that the availability of relevant data is weak.However, the continuity of the research theme is relatively good, and the analysis is mostly combined with the actual land use status and regional conditions in China.More and more scholars have started to use empirical methods to measure carbon emissions in different regions, different land types, and different land use methods, and pay more attention to research in a macroscopic direction.