Enhanced detriment to ecosystem carbon pools by global change factors and herbivory

Ecosystem carbon pools are being rapidly transformed by global change factors (GCFs) and trophic interactions within ecosystems. However, despite mounting evidence for the individual impacts of GCFs and herbivores on ecosystem carbon pools, the extent to which these factors interact to transform ecosystem carbon dynamics remains a major uncertainty, impeding efforts to guide ecosystem-based approaches by leveraging trophic managements to climate change adaption. By curating terrestrial and aquatic GCFs and trophic interactions full-factor paired experiments globally (544 paired observations from 121 studies), we revealed that the combined effects of GCFs and herbivores on ecosystem carbon pools were more detrimental than their individual effects, and these synergistic stressors of GCFs and herbivores posited slightly different impacts on vegetation and soil carbon pools, with a more detrimental effect on plant aboveground biomass and microbial biomass carbon. Furthermore, these negative combined effects were amplified in low-latitude regions, and aridity contributed the highest power for explaining the variability in these interactions, suggesting that these effects were more likely to harm ecosystem carbon stocks in regions with higher temperatures or stronger evapotranspiration. Overall, our findings underscore that the interplay between abiotic and biotic stressors can substantially undermine ecosystem carbon sequestration capacity, particularly in already vulnerable regions, calling for a reevaluation of current climate change mitigation strategies to explicitly account for and manage trophic interactions.