Vertical distribution of vegetation in mountain regions: A review based on bibliometrics

Vertical change and distribution of mountain vegetation have always been the focus of mountain ecology research. This paper reviewed the research progress on the vertical distribution pattern of mountain vegetation using methods of bibliometric statistics and literature analysis. Based on the database platform of CNKI and Web of Science, we searched for papers published in this field from January 1915 to December 2020 and analyzed the research history, present status, progress, and trend of vertical patterns of mountain vegetation. The results showed that the number of studies, authors, countries, and institutions in China and abroad has increased. The main research countries or regions cover 85 countries, including the United States, Germany, China, Spain, and France, with 34.7% of the literature concentrated in 25 major journals. Based on the CiteSpace software, this study analyzed the hot fields of the research on vertical distribution of mountain vegetation in China and abroad, and reviewed the theories, hypotheses, research methods, and main research fields. The vertical pattern of mountain vegetation was verified by using methods from single-factor description and multi-factor analysis to determination of mechanism and hypothesis. Representative theories included time theory, spatial heterogeneity theory, competitive coexistence theory, neutral theory, and niche theory. The research methods were summarized as traditional research methods, quantitative classification and environmental interpretation, remote sensing image information technology, models, and digital information technology. In this study, the research hotspots in China and abroad were also analyzed and reviewed from the aspects of the vertical distribution and driving factors of mountain vegetation, vertical change in mountain vegetation productivity, spectral structure of plant communities, and prediction of vegetation distribution based on niche theory. In short, in the context of global climate change, the response of mountain vegetation and ecosystems is sensitive and dramatic, and the response of mountain vegetation to climate change, digital information of vegetation vertical band spectrum, ecological cycle, and ecosystem services under water-soil coupling has received more attention. Multi-scale and multi-subject integration patterns are trends in the studied vertical distribution of mountain vegetation.