Rising utilization of stable isotopes in tree rings for climate change and forest ecology

Abstract

Analyses of stable isotopes (C, O, H) in tree rings are increasingly important cross-disciplinary programs. The rapid development in this field documented in an increasing number of publications requires a comprehensive review. This study includes a bibliometric analysis-based review to better understand research trends in tree ring stable isotope research. Overall, 1475 publications were selected from the Web of Science Core Collection for 1974–2023. The findings are that: (1) numbers of annual publications and citations increased since 1974. From 1974 to 1980, there were around two relevant publications per year. However, from 2020 to 2022, this rose sharply to 109 publications per year. Likewise, average article citations were less than four per year before 1990, but were around four per article per year after 2000; (2) the major subjects using tree ring stable isotopes include forestry, geosciences, and environmental sciences, contributing to 42.5% of the total during 1974–2023; (3) the top three most productive institutions are the Chinese Academy of Sciences (423), the Swiss Federal Institute for Forest, Snow and Landscape Research (227), and the University of Arizona (204). These achievements result from strong collaborations; (4) review papers, for example, (Dawson et al., Annu Rev Ecol Syst 33:507–559, 2002) and (McCarroll and Loader, Quat Sci Rev 23:771–801, 2004), are among the most cited, with more than 1000 citations; (5) tree ring stable isotope studies mainly focus on climatology and ecology, with atmospheric CO2 one of the most popular topics. Since 2010, precipitation and drought have received increasing attention. Based on this analysis, the research stages, key findings, debated issues, limitations and directions for future research are summarized. This study serves as an important attempt to understand the progress on the use of stable isotopes in tree rings, providing scientific guidance for young researchers in this field.