Vegetation responses in Alaskan arctic tundra after 8 years of a summer warming and winter snow manipulation experiment

• Published in: Global change biology 2005-04, Vol.11 (4), p.537-552
• Main Authors: Wahren, C.-H. A., Walker, M. D., Bret-Harte, M. S.
• Format: Article
• Language: English
• Subjects: climate change; Effects; Experiments; Flowers & plants; ITEX; passive warming; Snow; snow addition; Taiga & tundra; Temperature
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/j.1365-2486.2005.00927.x

We used snow fences and small (1 m2) open‐topped fiberglass chambers (OTCs) to study the effects of changes in winter snow cover and summer air temperatures on arctic tundra. In 1994, two 60 m long, 2.8 m high snow fences, one in moist and the other in dry tundra, were erected at Toolik Lake, Alaska. OTCs paired with unwarmed plots, were placed along each experimental snow gradient and in control areas adjacent to the snowdrifts. After 8 years, the vegetation of the two sites, including that in control plots, had changed significantly. At both sites, the cover of shrubs, live vegetation, and litter, together with canopy height, had all increased, while lichen cover and diversity had decreased. At the moist site, bryophytes decreased in cover, while an increase in graminoids was almost entirely because of the response of the sedge Eriophorum vaginatum. These community changes were consistent with results found in studies of responses to warming and increased nutrient availability in the Arctic. However, during the time period of the experiment, summer temperature did not increase, but summer precipitation increased by 28%. The snow addition treatment affected species abundance, canopy height, and diversity, whereas the summer warming treatment had few measurable effects on vegetation. The interannual temperature fluctuation was considerably larger than the temperature increases within OTCs (