Arctic ecosystem structure and functioning shaped by climate and herbivore body size

• Published in: Nature Climate Change
• Main Authors: Legagneux, P., Gauthier, G., Lecomte, N., Schmidt, N., Reid, D., Cadieux, M-C., Berteaux, D., Bêty, J., KREBS, C., Ims, R., Yoccoz, N., Morrison, R., Leroux, S., Loreau, Michel, Gravel, D.
• Other Authors: Université Laval Québec (ULaval), Université du Québec à Rimouski (UQAR), University of Tromsø (UiT), University of Moncton, Aarhus University Aarhus, Wildlife Conservation Society (WCS), University of British Columbia (UBC), Carleton University, Memorial University of Newfoundland St. John's, Station d’Ecologie Expérimentale du CNRS à Moulis (SEEM), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: Ecosystem ecology; Arctic ecosystem; [SDE.MCG]Environmental Sciences/Global Changes; Arctic; Climate change; Global warming; Tundra
• Online Access: https://hal-univ-tlse3.archives-ouvertes.fr/hal-02957858; https://doi.org/10.1038/nclimate2168

International audience Significant progress has been made in our understanding of species-level responses to climate change, but upscaling to entire ecosystems remains a challenge. This task is particularly urgent in the Arctic, where global warming is most pronounced. Here we report the results of an international collaboration on the direct and indirect effects of climate on the functioning of Arctic terrestrial ecosystems. Our data from seven terrestrial food webs spread along a wide range of latitudes (∼1,500 km) and climates (Δ mean July temperature = 8.5 °C) across the circumpolar world show the effects of climate on tundra primary production, food-web structure and species interaction strength. The intensity of predation on lower trophic levels increased significantly with temperature, at approximately 4.5% per °C. Temperature also affected trophic interactions through an indirect effect on food-web structure (that is, diversity and number of interactions). Herbivore body size was a major determinant of predator–prey interactions, as interaction strength was positively related to the predator–prey size ratio, with large herbivores mostly escaping predation. There is potential for climate warming to cause a switch from bottom-up to top-down regulation of herbivores. These results are critical to resolving the debate on the regulation of tundra and other terrestrial ecosystems exposed to global change.