Herbivores like reindeer need to navigate important fluctuations in the chemical composition of tundra plants over the summer season, as the quality of the vegetation changes. In their study, Berthelot and collaborators investigate whether long-term differences in temperature and reindeer management influence the quality of reindeer’s summer forage.
Fanny Berthelot, lead author of the study says: “To our knowledge, this is the first study that uses a large spatial sampling design to assess long-term impacts of herbivory and climate on plant nutritional quality (i.e., both defense and nutrient concentrations). We found substantial variations in plant chemical composition between species, and part of this between-species variation was associated with plant functional groups. We also documented strong seasonal decreases in the concentrations of nutrients (Nitrogen and Phosphorus) and weaker seasonal increases in the concentrations of defense compounds (Silicon and Phenolics) over the summer.
We also found a steeper seasonal decline in nutrient concentrations in warmer sites than in cooler sites, while defense compounds seemed not to be affected by the temperature. Interestingly, we found no evidence for long-term effects of reindeer grazing intensity on the average chemical composition of the plants.
Our results indicate that what is likely to matter to reindeer in term of plant quality seems to be seasonal variations in plant chemical composition as well as species composition of the pastures.”
Reference: Berthelot, F., Stien, A., Soininen, E.M., Tveraa, T., Böhner, H. and Bråthen, K.A., 2025. Are Large‐Scale Differences in Temperature and Reindeer Management Regime Affecting the Quality of Reindeer’s Summer Forage? Ecology and Evolution, 15(11): e72500. https://doi.org/10.1002/ece3.72500
Photo credit Fanny Berthelot