Forest Decline of the Genus Abies Due to Climate Change: Evidence from a Literature Review

Forest decline in genus Abies has been increasingly associated with drought, warming, pollution, and biotic disturbances. However, the importance of these drivers and the degree to which drought–bark beetles’ interactions have been studied in Abies remain insufficiently documented. This review aimed to identify the main reported causes of decline in Abies species worldwide and to assess the current state of knowledge on the drought–bark beetles’ interaction, with special attention to sacred fir (Abies religiosa) because of its ecological importance in Mexico and its role as a winter habitat for the monarch butterfly (Danaus plexippus). We reviewed 237 articles indexed in Scopus and complemented this analysis with bibliometric indicators and keyword co-occurrence maps generated using the Bibliometrix R package (version 5.4.1) and VOSviewer (version 1.6.12). The main causes of decline were drought, pollution, and rising temperatures, affecting 41 taxa in 28 countries. Although drought has been reported throughout the study period (1977–2026), publications linking drought and warming to Abies decline have increased markedly during the last 15 years. Bibliometric results indicate that drought–bark beetles’ interactions have been extensively studied in Pinus and Picea, whereas comparable evidence for Abies remains limited. Future management should integrate monitoring, stand-density regulation, pest surveillance, and climate-adaptation strategies implemented by forest managers, conservation agencies, and local communities.