Long‐term herbivore removal experiments reveal how geese and reindeer shape vegetation and ecosystem CO 2 ‐fluxes in high‐ Arctic tundra

作者：Matteo Petit Bon, Brage Bremset Hansen, Maarten J. J. E. Loonen, Alessandro Petraglia, Kari Anne Bråthen, Hanna Böhner, Kate Layton‐Matthews, Karen H. Beard, Mathilde Le Moullec, Ingibjörg S. Jónsdóttir, René van der Wal · 发表于：Journal of Ecology · 年份：2023 · DOI：10.1111/1365-2745.14200 · 被引用次数：20 · 研究领域：Climate change and permafrost、Cryospheric studies and observations、Rangeland and Wildlife Management

Abstract Given the current rates of climate change, with associated shifts in herbivore population densities, understanding the role of different herbivores in ecosystem functioning is critical for predicting ecosystem responses. Here, we examined how migratory geese and resident, non‐migratory reindeer—two dominating yet functionally contrasting herbivores—control vegetation and ecosystem processes in rapidly warming Arctic tundra. We collected vegetation and ecosystem carbon (C) flux data at peak plant growing season in the two longest running, fully replicated herbivore removal experiments found in high‐Arctic Svalbard. Experiments had been set up independently in wet habitat utilised by barnacle geese Branta leucopsis in summer and in moist‐to‐dry habitat utilised by wild reindeer Rangifer tarandus platyrhynchus year‐round. Excluding geese induced vegetation state transitions from heavily grazed, moss‐dominated (only 4 g m −2 of live above‐ground vascular plant biomass) to ungrazed, graminoid‐dominated (60 g m −2 after 4‐year exclusion) and horsetail‐dominated (150 g m −2 after 15‐year exclusion) tundra. This caused large increases in vegetation C and nitrogen (N) pools, dead biomass and moss‐layer depth. Alterations in plant N concentration and CN ratio suggest overall slower plant community nutrient dynamics in the short‐term (4‐year) absence of geese. Long‐term (15‐year) goose removal quadrupled net ecosystem C sequestration (NEE) by increasing ecosystem photosynthesis...