The industrial attributes of environmental dependence and resource consumption determine the binary contradiction between tourism destination and ecological environment (Pang et al., 2011). The three topics of TES, tourism ecological risk, and tourism ecological health, which specifically characterize the safety, risk, and health of the tourism ecosystem, can accurately describe and reflect the status, threat, and coordination of the ecological environment under the influence of tourism activities. These three are the key factors for analyzing and evaluating the ecological security of tourist destinations and promoting the construction of ecological civilization.

TES refers to the rational development of tourism resources and effective management of the tourism ecological environment within certain ranges of time and space, so that the tourism ecosystem has the relative stability of structure and diversity of functions, and can also provide rich material resources and harmonious environmental space for the development of tourism, as well as maintain the coordinated development of the natural-society-economic complex ecosystem of the tourist destinations (Li et al., 2013). Meanwhile, as ecological risk is the inverse function of ecological security (Xiao et al., 2002), tourism ecological risk refers to the process of describing and evaluating the possibility and magnitude of adverse effects of tourism activities on the ecosystem and its components at a regional scale (Zhong and Li, 2014). In addition, the status of tourism ecological health shows that the tourism ecological system is stable, dynamic and sustainable, i.e., the system can maintain its organizational structure, produce tourism products and services, meet the needs of the sustainable development of tourism destinations, and automatically recover within a period of time after being disturbed by human tourism activities (Zhou et al., 2015c).

This study found that there are highly dialectical relations of the unity of opposites and coordination among these three topics. 1) In terms of causal logic, TES research originates from ecological risks in the tourism development process (Xiao et al., 2002). On this basis, the feedback loop of “identification of tourism ecological risk-improvement of TES” is the driving force for destination ecological civilization construction. Ecological health is one of the development goals of TES, so that the benign evolution of “identification of tourism ecological risk-improvement of ecological security-sustainability of ecological health” is an effective approach to ameliorate the destination environment. 2) In terms of the breadth and depth of the research contents, all three have undergone research process from theory to demonstration. At present, TES has gradually formed the internal logic of “evaluation-influencing factors-early warning-regulation”, while neither tourism ecological risk nor tourism ecological health have formed a clear framework yet. 3) In terms of research level, in 2020, the National Overall Planning for Major Ecosystem Protection and Restoration Projects (2021-2035) proposed to focus engineering construction on the development and optimization of a national ecological security barrier system, making ecological security one of the major national strategies. Tourism ecological risk and ecological health are important research issues, with a trend toward multiplicity and practicality. Undeniably, research on TES still shows irreplaceable dominance, and the three topics are important issues for the sustainable development and ecological civilization construction of destinations.

Based on the above considerations, TES is not only the basic research work of ecological health, but also the foothold of ecological risk research. Together with the emphasis and support of national macro policies, TES research clearly has irreplaceable leadership among the three themes. From the current research situation, the TES research system is relatively sound, so it can provide a certain reference for tourism ecological risk and tourism ecological health research. In terms of practical significance, the three themes are all important topics of sustainable development and ecological civilization construction.

Chinese research was mainly retrieved from the CNKI database. In the specific retrieval process, this paper takes the CSSCI, CSCD and Peking University core journals as the source limitation, setting “ecological security”, “ecological risk” and “ecological health” and respectively adding “tourism”, “scenic area” and “scenic spot” as the key words. Using these criteria, 316 articles were obtained. After collection and arrangement, this paper excluded repeated and irrelevant articles, and ultimately 228 articles were obtained, which were published from September 2000 to August 2021. Judging from annual publication counts, there are few studies from 2000 to 2004, with 5 or less articles published annually. Since 2005, the number of articles published has increased rapidly, with 19 articles published in 2020. According to Fig. 1, the Chinese research on TES generally presents a trend from slow growth to sharp growth.

English research was mainly retrieved through the Web of Science database. With “ecological security”, “ecological risk”, “ecological safety” and “ecological health” and respectively adding “tourism”, “scenic spot” as the key words, 263 articles were retrieved. After applying the exclusion criteria above, 114 articles were obtained, which were published from April 2000 to August 2021. Judging from annual publication counts, there are few studies from 2000 to 2005, with only 1 article annually. Since 2006, the number studies began to increase, but with fluctuations. From 2013 to 2021, the number of relevant articles grew rapidly with 114 articles published, which accounted for 79% of the total number, and the number of articles reached 23 in 2019. According to Fig. 1, the English research on TES generally presents a trend from slow growth to fluctuating growth.

Since the 1970s, many international conferences, conventions, and organizations have been crucial to the promotion of global environmental protection, such as The United Nations Conference on the Human Environment, Agenda 21, Vienna Convention, United Nations Framework Convention on Climate Change, International Organization for Standardization (ISO), etc. Guided by the trend of worldwide environmental protection, the promulgation of Regulations on the Administration of Construction Project Environmental Protection in 1981 marked the formal implementation of an environmental impact assessment system in China. In this context, the research on TES started to sprout. In the germination stage, research activity on TES began to increase with gradually extended topics, which conforms to the development process of academic research from the outside to the inside, but it still possessed significant scattered and spontaneous research characteristics. In general, our analysis of the related research reveals three main characteristics. 1) The characteristic of marginalization is significant. With increased attention, research on the relevant conception is prominent, which shows a slow trend of focalization. In early research, scholars just marginally mentioned ecological security (Jin, 2000) and ecological risk (Burger, 2000), and the research mainly focused on the ecological imbalance pressure (Duffy et al., 2001) caused by tourism activities on tourist destinations. Meanwhile, the focus gradually shifted to theoretical monographic research on the analysis of relationships between ecological security and tourism (Shang and Zhao, 2003). 2) Relevant research is mainly focused on the small-scale. Scholars mostly conducted research from the scale of scenic lake spots (Dong, 2003), while large-scale studies at the national and provincial dimensions were rarely conducted. 3) Most of the research topics are accompanied by eco-tourism, sustainable development, western development, etc., which are characterized by the developments of the times. Since the 1970s, with the implementation of global environmental management practices and China’s western development policy, academic research has presented close practice integration and topic extension.

Since 2005, there has been a high incidence of global environmental pollution accidents. Therefore, many international environmental protection organizations had taken a series of measures to further improve the level of environmental management, such as the release of Millennium Ecosystem Assessment and The Sydney Declaration, as well as the convening of the first United Nations Environment Assembly. Overall, international environmental management in the exploration stage shows a significant change from post-coordination to pre-prevention.

Reviewing the exploration stage, TES research presents a trend from rapid growth to fluctuating growth with the characteristics of constantly strengthened standardization and systematization. In general, the research of this stage presents four main characteristics. 1) The core trend of field research is gradually obvious. In this stage, the focus of research topics was becoming more and more prominent, the discussions of scholars mainly centered around three topics: tourism ecological risk (Zhong and Li, 2014), TES (Liu et al., 2009) and tourism ecological health (Zhou et al., 2015d). 2) Field research presents a significant shift from conceptual and theoretical research to empirical research. During this stage, the research perspective gradually shifted from conceptual discrimination (Wu, 2005) to quantitative analysis, in which the research topics were more inclined toward ecosystem security/risk/health evaluation, early warning system construction (You et al., 2014b), dynamic simulation (Wu et al., 2013), etc. 3) The vertical extensibility of research topics is continuously improved, and interdisciplinary characteristics emerge. In this stage, the level of research field was gradually enriched, yet a standardized logic system had not been formed. In specific research, topics such as the coordination of ecology and economy (Zhou et al., 2015a), identification of sensitive areas (You et al., 2014a), and evaluation criteria (Wang and Wu, 2013) were involved. Relevant research showed the characteristics of interdisciplinary integration, including tourism (He et al., 2018), ecology (Jurado et al., 2012), sociology (Zhou, 2011), chemistry (Ye et al., 2015) and other fields. For example, the research on the division of government and market based on TES emerged. 4) Compared with Chinese research, English research slightly lags behind, but it presents a significant feature of detailed research. Especially, English research characterized by in-depth and detailed analysis was significant, and much of the research had provided a deeper and more detailed theoretical foundation and practical thinking for subsequent research, such as the research of destination vulnerability and resilience assessment (Calgaro et al., 2014), or the integrated index of eco-space importance (Xie et al., 2014).

Since 2017, global environmental management has shifted from conceptual and holistic governance to specific and breakthrough rectification. The promotion of numerous international measures reflects the pertinence of global resource conservation and environmental governance, such as the establishment of the ecological civilization system in China, the proposal of carbon neutralization and carbon peak (Tang et al., 2021) and the UN’s call for “zero pollution earth”. Overall, international environmental governance presents the remarkable characteristics of systematization and breakthrough in this stage.

In the development stage, TES research shows a surging trend in quantity, and it has gradually become an important research direction and topic of sustainable tourism development with the significant characteristics of multidimensional promotion. In general, the research in this stage presents four main characteristics. 1) Pattern research gradually formed, with innovation in some cases. In this stage, the research content gradually tended toward the internal logic of “evaluation-influencing factors-early warning-regulation”. On this basis, the research framework system was gradually completed, and the research context of each branch topic has gradually taken shape. Meanwhile, driven by climate change, international environmental management has taken on a brand-new look. Scholars actively combine practices to explore innovative topics, such as the dynamic evaluation of TES (Xu et al., 2021), spatio-temporal patterns and spatial effects (Li et al., 2017), etc., which shows the characteristics of the new times. 2) The professional and scientific nature is more significant. In this stage, related research places more emphasis on the interaction between tourism system and ecosystem. By constructing the logical framework of TES assessment for dynamic evolution, early warning and regulation, relevant research has gradually realized the multi-faceted systematic practice of human response, ecological restoration, early warning and regulation in the changing process of TES. 3) The research scale is diversified, and large-scale research has increased significantly. The research tends to cover diverse scales, such as national and provincial (Xu et al., 2021), city and county (He et al., 2020), river basins (Yin and Zheng, 2017), scenic spots (Bao and Liu, 2017), etc. Overall, large-scale research shows an obviously surging trend. 4) Academic dialogues in the TES field have become more frequent, which is manifested in the increasing frequency of international publications on Chinese research (Ruan et al., 2019; Shi et al., 2020). On the one hand, this shows that the international vision of TES research is becoming wider and wider. On the other hand, it shows that the barriers to academic dialogue and communication in the field are gradually decreasing, and less information asymmetry means deeper thinking and more efficient practical measures.

TES research initially focused on phenomenon description analysis and relationship speculation, and gradually evolved into the comprehensive application of field research, statistical measurement and geospatial research methods. English research mostly adopts the interview method, field research and the geospatial analysis method. In the early stage of Chinese research, qualitative methods of phenomenon description and law extraction were adopted. In recent years, the method system presents significant empirical characteristics, with various method systems introduced gradually, such as statistical measurement and the geospatial research method. Specifically, scholars comprehensively apply various analytical methods like the modeling, index, fuzzy evaluation and spatial analysis methods to discuss the evaluation and quantification of TES with the support of remote sensing and GIS technology (Yan et al., 2012). The specific research methods used by scholars on various hot research topics are listed in Table 1.

The multiple characteristics of research topics in the TES field are remarkable, showing a trend of change from theoretical discrimination to empirical research, and from focused research to progressive research. The security of various resource elements in tourism destinations, such as the security of land, forests, and biology, has become the re-search theme of scholars. Most of them use specific case sites as the starting point to analyze their ecological security status in detail, involving the evaluation, early warning and regulation of specific tourism ecological issues. The potential ecological risks under the distribution of heavy metals in typical tourist destinations, the division of labor between the government and the market from the perspective of ecological security, and the popularization of TES science have gradually come into the research fields of scholars, which also represent a positive response to global environmental management and multidisciplinary research.

Overall, TES research presents four main characteristics.

(1) The phased characteristics are significant, and a relatively standard research framework has been formed. Through literature review, it is found that TES research at home and abroad has significant phased characteristics in terms of the number of publications and research topics, presenting distinct stages of germination, exploration and development. Currently, TES research presents a relatively standardized research framework of “evaluation - influencing factors - early warning - regulation”. Chinese studies started earlier, while foreign studies have developed rapidly in recent years.

(2) The empirical orientation of the research methods is distinct. In recent years, TES research has constantly drawn on the theories and methods of ecology, management, economics, etc., mainly focusing on the aspects of evaluation, influencing factors, early warning and regulation, discussing scientific issues of how to evaluate, what the trend is, and how to manage or prevent the ecological problems, and ultimately showing empirical and in-depth characteristics. However, due to many obstacles in theory and practice, a unified index system and evaluation method has not yet been established.

(3) The development trend is characterized by small-scale dominance and a large-scale surge. At present, small-scale research focuses on the ecological security issues of typical tourist destinations, which will provide references for the same type of TES governance. Meanwhile, large-scale research, accompanied by the implementation of national policies, focuses on regional TES issues, so as to provide ideas for targeted regional regulation measures. Limited by various unstable factors such as chaotic ecological security thresholds, differences in data availability and changeable state evolution, there are some shortcomings in the accuracy of TES research at different scales. Meanwhile, many subjective and objective factors will affect the scientific nature of TES research on different scales, such as the universality of research methods, the interpretation level of evaluation results, and the perspectives of early warning and regulation.

(4) The disciplinary integration and practical combination have been continuously strengthened. The TES research process basically forms two paths. One is based on the theory of ecological security, which is presented as the deep logical contemplation of the relationship between ecological security and ecotourism, so that the characteristics of the multidisciplinary integration of TES research have been strengthened. The second path is to focus on the empirical perspective and carry out diversified level research on scale, theme and theory under the dual guidance of environmental management policy and destination ecological practice. In contrast, English research is relatively lagging, and it needs to be strengthened in two aspects: boundary definition and TES focus. Although Chinese research has a large base, it still needs more in-depth exploration in both research entry points and topic depth.

Combined with the current practice and development of TES, future research can focus on four main areas.

(1) Strengthen research on thresholds, early warning and regulation. A highly recognized index system, threshold standards and research methods have not yet been established. There are also several deficiencies in the existing research, such as: the establishment of the index system structure and the selection of indicators are highly subjective; the threshold and grading standards of evaluation and early warning have not been unified yet; the introduction of research methods in different disciplines lacks evaluation criteria, and the universality needs to be verified; the methods and standard application of early warning research lack necessary validation, etc. One suggestion is to optimize the early warning and regulation model of TES by using big data mining algorithms and visualization, combined with a scientific time series model. According to the national ecological security red line standard, the bottom line and threshold of TES should be determined. At the same time, future research should simulate different development scenarios based on diversified ecological data, so as to put forward an optimization plan of TES regulation.

(2) Improve the application of big data. TES research involves multiple disciplines. In addition to traditional environmental, economic, social, and ecological indicators, technical indicators such as land use are also introduced, but wetland and atmospheric indicators are rarely introduced. The accuracy, type, and time nodes of the data collected by different disciplines are also different. Integrating these multi-source and heterogeneous data into TES research is the key difficulty of current research. For example, the current ecological data statistics in China are obviously lagging behind the socio-economic data, and there are great differences in the statistical caliber in different years, resulting in the poor comparability. Therefore, it will be necessary to improve the application of big data in the field research of TES in the future, that is, to realize real-time, traceable and predictable dynamic evaluation, early warning and regulation, in order to promote the controllability and dataization of tourism in ecological civilization construction.

(3) Construct the synergistic effect mechanism between tourism and ecology. At the theoretical level, the hot issues in current tourism ecology research are how to coordinate the relationship between tourism development and ecological protection, as well as reasonably maintain and improve TES (Zhou et al., 2015a). For a long time, TES research has focused on geography and ecology. In the future, it will be necessary to measure the value and contribution of TES to the destination economy/society/culture, tourism consumption, tourism production, and the impact on the overall strategic layout, in order to explore the synergy between tourism and ecology in a wide range, and achieve high-quality development in the field. At the practical level, one important direction will be to strengthen the construction of the policy system of TES and boost the strategic layout of ecological civilization. China’s ecological security policy system includes ecological space management policy, environmental pollution prevention policy, ecological risk control policy, incentive policy and performance appraisal policy (Cheng et al., 2019). However, the current TES research is not closely related to the national ecological civilization construction strategy or the national land ecological security policy, and it fails to provide forward-looking guidance for policy formulation. Therefore, it is necessary to carry out forward-looking evaluation on the mechanism and effects of various policies, in order to sort out and strengthen the construction of the TES policy system.

(4) Realize the longitudinal deepening and interconnection of scale research. Firstly, based on accurate data, small-scale TES research makes it easier to obtain scientific and reasonable conclusions. While ensuring its accuracy, future research should strengthen horizontal comparative studies and improve the typical case study, so as to provide a basis for micro-destination TES research and practice. Secondly, large-scale TES research has stronger data availability, and in-depth research from the macro perspective can provide a reference for national strategies and regional coordination of tourism ecological measures. Based on the improved data accuracy by the big data algorithm, future research should further strengthen the collaborative research between tourism and the regional economy, society and culture, so as to realize the strategic guidance of TES research for practice, and take this as a breakthrough to realize the space-time linkage in the dynamic evolution of TES. In order to promote field dialogue and better realize the ecological civilization construction, a major trend in the future will be to realize the interconnection of TES research results at different scales through data mining and processing algorithms. Last but not least, boosting tourists' green consumption (Tang et al., 2022a) and promoting area’s green development (Tang et al., 2022b) are of great significance to maintain and improve the ecological security of tourism destinations. This is also an important measure to realize the ecological security and ecological civilization construction of tourism destinations from the micro level, which is beneficial to the longitudinal deepening and interconnection of scale research.