*5.3. Limitations and Future Research Directions*

This paper presented an evaluation method and constructed a symbiotic interaction mechanism between tourism's carbon emission efficiency and the tourism economy's highquality development in the Yellow River Basin, which provides theoretical support for the subsequent evaluation and practical basis for subsequent policy practice. However, due to the availability of data and the inadequacy of previous relevant studies, the selection and

establishment of the index system may have deficiencies. At the same time, the selection of indicators are quantitative indicators without qualitative evaluation, which has limitations. To select a case in this paper, on the other hand, there is a limit too. It can only reflect the status of the Yellow River basin, a single specific area. At the same time, the influencing factors of the interaction mechanism were not further subdivided, such as the different effects of political, economic, cultural, social, and ecological factors on the interaction mechanism.

Thus, in the future, the measurement of tourism's carbon emission and its efficiency should be more precise and specific. For example, a variety of methods can be used to compare to obtain more accurate results, or the carbon emissions of the ecosystem in terms of technogenic pollution can be taken into account. Further exploration will be carried out from the aspects of technology and energy efficiency, such as studying the impact of existing technologies on tourism's carbon emission efficiency and further on tourism economy or the impact of innovative technologies on energy efficiency in tourism. Secondly, the symbiotic interaction mechanism between tourism's carbon emission efficiency and the tourism economy's high-quality development can be explored from multiple regions and multiple levels. On the basis of expanding the research area, different research scales were explored from different levels, such as region, city, county, or village to build a complete interactive mechanism model. Thirdly, the symbiotic interaction mechanism between tourism carbon emission efficiency and tourism economy high-quality development was studied from multiple perspectives. To improve the selection of influencing factors and the establishment of the index system, different mechanisms of action can be studied from the internal and external aspects of the symbiotic interaction system. On this basis, different types of influencing factors can be explored separately to find the commonality and individuality of each type of factor.

**Author Contributions:** Conceptualization, S.L. and Z.C.; methodology, S.L. and Z.C.; funding acquisition, Y.T. and B.H.; investigation, S.L., Z.C., Y.T. and B.H.; resources, Z.C.,Y.T. and B.H.; software, S.L. and Z.C.; formal analysis, S.L. and Z.C.; data curation, S.L.; writing—original draft preparation, S.L. and Z.C.; writing—review and editing, S.L. and B.H.; visualization, S.L.; supervision, B.H.; project administration, B.H. and Y.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Project of Hainan Academician Innovation Platform Scientific Research (YSPTZX202210), the Project of National Social Science Foundation of China (21BJY194).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The sources of relevant data acquisition have been described in the text.

**Conflicts of Interest:** The authors declare no conflict of interest.
