Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome

Invertebrateherbivores depend on external temperature for growth and metabolism. Continued warming in tundraecosystems is proposed to result in increased invertebrateherbivory. However, empirical data about how current levels of invertebrateherbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrateherbivory across the tundrabiome at the community level and explored how these patterns are related to long-term climatic conditions and year-of-sampling weather, habitat characteristics, and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundrasites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebratesfor the most common plant species within each plot. Overall, invertebrateherbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant biomass. Our results suggest that mid-summer temperature influences the intensity of invertebrateherbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebratesin the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrateherbivory are necessary to predict the consequences for rapidly changing tundraecosystems.