Synergistic pest outbreaks and climate extremes amplify forest health risks

Forest pests and pathogens represent major drivers of forest decline globally, and their impacts are increasingly shaped by interactions with extreme climatic events. Yet, how multiple pest guilds (diseases, insects, and rodents/lagomorphs) interact with each other and with climate extremes to influence forest health remains poorly understood, particularly in temperate–subtropical regions. Here, I synthesized nationwide forest pest monitoring data (2014–2023) across China to investigate (1) the potential for co-occurrence among different pest types and (2) the compound effects of pest interactions and climate extremes on forest risk.I found that insects dominated forest pest damage nationally, while diseases and rodent/lagomorph damage exhibited strong regional heterogeneity, particularly in arid and temperate zones. Correlation analyses revealed significant positive associations between insect damage and both disease and rodent/lagomorph damage, suggesting that insects may act as a “bridge” facilitating multi-pest outbreaks. Generalized linear mixed models showed contrasting climatic sensitivities: forest diseases were exacerbated by both drought and extreme rainfall, insect damage was linked to extreme rainfall, whereas rodent damage declined under drought. Structural equation modeling further revealed that climate extremes indirectly intensified disease risk via pest co-occurrence, highlighting a key pathway of compound biotic–abiotic disturbances.Our findings demonstrate that forest health risks in China are jointly shaped by synergistic pest interactions and climate extremes, underscoring the need for integrated, multi-pest monitoring and climate-informed early warning systems. This study provides one of the first nationwide assessments of pest co-occurrence and compound climate effects, offering a new framework for forest risk prediction and adaptive management under climate change.