Arctic greening from warming promotes declines in caribou populations

• Published in: Science Advances
• Main Authors: Ranga B. Myneni, Taejin Park, Per Fauchald, Hans Tømmervik, Vera Helene Hausner
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Association for the Advancement of Science (AAAS) 2017
• Subjects: Research Article; Research Articles; SciAdv r-articles; Applied Ecology; Arctic sea ice; Climate change; Normalized Difference Vegetation Index; population dynamics; Rangifer tarandus; VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Zoogeografi: 486; VDP::Mathematics and natural science: 400::Zoology and botany: 480::Zoogeography: 486; envir; geo; Arctic; Arctic Ocean; Arctic Greening; Sea ice; Tundra
• Online Access: https://advances.sciencemag.org/content/advances/3/4/e1601365.full.pdf; https://doi.org/10.1126/sciadv.1601365; http://europepmc.org/articles/PMC5406139; https://hdl.handle.net/10037/11387; https://syndication.highwire.org/content/doi/10.1126/sciadv.1601365; https://advances.sciencemag.org/content/3/4/e1601365.full; https://europepmc.org/abstract/MED/28508037; https://www.ncbi.nlm.nih.gov/pubmed/28508037; https://brage.bibsys.no/xmlui/handle/11250/2441571; https://ui.adsabs.harvard.edu/abs/2017SciA.3E1365F/abstract; http://advances.sciencemag.org/content/3/4/e1601365.full; https://munin.uit.no/handle/10037/11387; https://brage.nina.no/nina-xmlui/handle/11250/2441571; https://academic.microsoft.com/#/detail/2608825455

A greener Arctic does not benefit caribou; the shift in tundra vegetation due to warming is associated with declining caribou herds. The migratory tundra caribou herds in North America follow decadal population cycles, and browsing from abundant caribou could be expected to counteract the current climate-driven expansion of shrubs in the circumpolar tundra biome. We demonstrate that the sea ice cover in the Arctic Ocean has provided a strong signal for climate-induced changes on the adjacent caribou summer ranges, outperforming other climate indices in explaining the caribou-plant dynamics. We found no evidence of a negative effect of caribou abundance on vegetation biomass. On the contrary, we found a strong bottom-up effect in which a warmer climate related to diminishing sea ice has increased the plant biomass on the summer pastures, along with a paradoxical decline in caribou populations. This result suggests that this climate-induced greening has been accompanied by a deterioration of pasture quality. The shrub expansion in Arctic North America involves plant species with strong antibrowsing defenses. Our results might therefore be an early signal of a climate-driven shift in the caribou-plant interaction from a system with low plant biomass modulated by cyclic caribou populations to a system dominated by nonedible shrubs and diminishing herds of migratory caribou.