Mycorrhizal fungi are an integral component of carbon and nutrient dynamics in soils and may be especially important in Arctic and alpine communities undergoing large-scale changes due to climate change. Large mammalian herbivores may influence these microbes indirectly by selectively foraging on certain plant types, and directly through trampling and nutrient addition to soils. Our study utilized DNA amplicon sequencing within a network of large mammalian herbivore exclosures across the Arctic to evaluate the impact of these herbivores on three types of mycorrhizal fungi: arbuscular mycorrhiza (AM), ectomycorrhiza (EcM), and ericoid mycorrhiza (ErM).
Large mammalian herbivores influenced the AM community across the sites but did not have a consistent effect on the EcM or ErM communities. We also observed effects of pH and growing season temperature on AM fungal communities which may indicate that conditions are becoming more favourable for AM fungi in these regions. AM fungi are understudied in the Arctic as they are typically cold-limited, but with climate change they may have the potential to expand.
EcM and ErM fungal communities were primarily correlated with soil properties, such as δ15N signature, and may be more closely tied to nutrient conditions in the soil rather than indirect effects from higher trophic levels. Current investigations into how mycorrhizal fungal activity and production is correlated to herbivory and soil conditions is currently ongoing, along with a larger biogeographical synthesis of mycorrhizae in the Arctic.
Reference: Brachmann, C.G., Ryberg, M., Furneaux, B.R., Rosling, A., Ou, T., Ekblad, A., Abdulmanova, S., Barrio, I.C., Bret-Harte, M.S., Fritze, H., Gough, L., Hollister, R.D., Jónsdóttir, I.S., Kalttopää, O., Lindén, E., Mäkiranta, P., Olofsson, J., Partanen, R., Reid, K.A., Sokolov, A., Sujala, M.S., Sundqvist, M.K., Suominen, O., Tweedie, C.E., Young, A. and Björk, R.G. (2025), Impacts of large herbivores on mycorrhizal fungal communities across the Arctic. Ecography e08045. https://doi.org/10.1002/ecog.08045