Herbivores may counteract climate warming impacts on tundra by reducing plant growth. However, the strength of this effect may depend on prevailing climatic conditions. To study how ungulates interact with temperature to influence growth of tundra shrubs across the Arctic tundra biome, we assembled dendroecological data from 20 sites, comprising 1,153 individual shrubs and 22,363 annual growth rings.
Interestingly, evidence for ungulates suppressing shrub growth was only observed at intermediate summer temperatures, and even at these temperatures the effect was minor. Forage preferences and landscape use of the ungulates may explain these results, as well as favorable climatic conditions that may enable effective compensatory growth of shrubs. Earlier local studies have shown that ungulates may counteract the impacts of warming on tundra shrub growth, but we demonstrated that ungulates’ potential to suppress shrub growth is not always evident and may be limited to certain temperature and precipitation conditions.
Reference: Vuorinen, K., Austrheim, G., Tremblay, J.-P., Myers-Smith, I.H., Hortman, H.I., Frank, P., Barrio, I.C., Dalerum, F., Björkman, M.P., Björk, R.G., Ehrich, D., Sokolov, A., Sokolova, N., Ropars, P., Boudreau, S., Normand, S., Prendin, A.L., Schmidt, N.M., Pacheco, A., Post, E., John, C., Kerby, J.T., Sullivan, P.F., Le Moullec, M., Hansen, B.B., Van der Wal, R., Pedersen, Å.Ø., Sandal, L., Gough, L., Young, A., Li, B., Magnússon, R.Í., Sass-Klaassen, U., Buchwal, A., Welker, J.M., Grogan, P., Andruko, R., Morrissette-Boileau, C., Volkovitskiy, A., Terekhina, A., Speed, J.D.M., 2022. Growth rings show limited evidence for ungulates’ potential to suppress shrubs across the Arctic. Environmental Research Letters. https://iopscience.iop.org/article/10.1088/1748-9326/ac5207/meta
This paper is a contribution to the DISENTANGLE project and was included as one of the chapters of Katariina’s PhD at the Norwegian University of Science and Technology.
Photograph: Muskoxen (Ovibos moschatus) in a willow patch (photo: Katariina Vuorinen)