Holocene pollen records from the central Arctic Foothills, northern Alaska: testing the role of substrate in the response of tundra to climate change

• Published in: Journal of Ecology
• Main Authors: Oswald, W. Wyatt, Brubaker, Linda B., Hu, Feng Sheng, Kling, George W.
• Other Authors: § Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA, * College of Forest Resources, University of Washington, Seattle, WA 98195, USA, † Quaternary Research Center, University of Washington, Seattle, WA 98195, USA, † Departments of Plant Biology and Geology, University of Illinois, Urbana, IL 61801, USA, and
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Blackwell Science Ltd 2003
• Subjects: Alaska; North Slope; Palaeoecology; Palynology; Toolik Lake; Ecology and Evolutionary Biology; Science; Arctic; Alaska North Slope; Arctic and Alpine Research; Climate change; north slope; permafrost; Rubus chamaemorus; Tundra
• Online Access: https://hdl.handle.net/2027.42/73204; https://doi.org/10.1046/j.1365-2745.2003.00833.x

1 To explore the role of edaphic controls in the response of arctic tundra to climate change, we analysed Holocene pollen records from lakes in northern Alaska located on glaciated surfaces with contrasting soil texture, topography and tundra communities. Using indicator taxa, pollen accumulation rates (PARs) and multivariate comparison of fossil and modern pollen assemblages, we reconstructed the vegetational changes at Upper Capsule Lake (Sagavanirktok surface) and Red Green Lake (Itkillik II surface) in response to increased effective moisture between the early and middle Holocene. 2 In the Red Green record, low PARs and the continuous presence of taxa indicative of prostrate-shrub tundra (PST; Equisetum , Polypodiaceae, Thalictrum and Rosaceae) indicate that the vegetation resembled PST throughout the Holocene. During the warm, dry early Holocene (11 300–10 000 cal years BP), PST also occurred on Sagavanirktok surfaces, as evidenced by PST indicators (Bryidae, Polypodiaceae, Equisetum and Rosaceae) in this interval of the Upper Capsule record. However, PARs increased, suggesting increased vegetation cover, PST taxa declined and taxa indicative of dwarf-shrub tundra (DST; Rubus chamaemorus and Lycopodium annotinum ) increased between 10 000 and 7500 cal years BP. 3 We hypothesize that between the early and middle Holocene the fine-textured soils and smooth topography of Sagavanirktok surfaces led to increased soil moisture, greater vegetation cover, permafrost aggradation, anoxic and acidic soil conditions, slower decomposition and the development of a thick organic layer. In contrast, soil moisture remained low on the better-drained Itkillik II surface, and vegetational changes were minor. 4 Landscape-scale substrate variations have an effect on how tundra responds to climate change, suggesting that the response of arctic ecosystems to future variability may be spatially heterogeneous. Journal of Ecology (2003) 91 , 1034–1048 Peer Reviewed ...