Bark beetle-driven community and biogeochemical impacts in forest ecosystems: a review.

This article reviews the ecological and biogeochemical impacts of phloem-boring bark beetles (Coleoptera: Curculionidae: Scolytinae) on conifer forests, focusing on tree mortality, decomposition, and ecosystem processes. Bark beetle outbreaks cause large-scale tree death, producing substantial deadwood that influences nutrient cycling, microbial and invertebrate community succession, and forest regeneration through distinct green, red, and gray mortality phases. The bark beetle holobiont, including symbiotic fungi (notably ophiostomatoid "blue-stain" fungi), bacteria, yeasts, and mites, mediates physical and chemical changes in attacked trees, affecting decomposition dynamics and interactions with other decomposers such as termites. While bark beetle disturbances alter soil, litter, and deadwood communities and biogeochemical cycles—especially carbon and nitrogen fluxes—responses vary widely by phase, location, and severity, with many knowledge gaps remaining, particularly regarding long-term ecosystem effects, geographic breadth, and interactions with climate change. The review highlights the need for interdisciplinary research to better understand and model bark beetle impacts on forest ecosystems globally.