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dc.contributor.authorTinner, W
dc.contributor.authorBigler, C
dc.contributor.authorGedye, S
dc.contributor.authorGregory-Eaves, I
dc.contributor.authorJones, RT
dc.contributor.authorKaltenrieder, P
dc.contributor.authorKrähenbühl, U
dc.contributor.authorHu, Feng Sheng
dc.date.accessioned2013-11-15T13:24:23Z
dc.date.issued2008-03
dc.description.abstractRecent observations and model simulations have highlighted the sensitivity of the forest–tundra ecotone to climatic forcing. In contrast, paleoecological studies have not provided evidence of tree-line fluctuations in response to Holocene climatic changes in Alaska, suggesting that the forest–tundra boundary in certain areas may be relatively stable at multicentennial to millennial time scales. We conducted a multiproxy study of sediment cores from an Alaskan lake near the altitudinal limits of key boreal-forest species. Paleoecological data were compared with independent climatic reconstructions to assess ecosystem responses of the forest–tundra boundary to Little Ice Age (LIA) climatic fluctuations. Pollen, diatom, charcoal, macrofossil, and magnetic analyses provide the first continuous record of vegetation–fire–climate interactions at decadal to centennial time scales during the past 700 years from southern Alaska. Boreal-forest diebacks characterized by declines of Picea mariana, P. glauca, and tree Betula occurred during the LIA (AD 1500–1800), whereas shrubs (Alnus viridis, Betula glandulosa/nana) and herbaceous taxa (Epilobium, Aconitum) expanded. Marked increases in charcoal abundance and changes in magnetic properties suggest increases in fire importance and soil erosion during the same period. In addition, the conspicuous reduction or disappearance of certain aquatic (e.g., Isoetes, Nuphar, Pediastrum) and wetland (Sphagnum) plants and major shifts in diatom assemblages suggest pronounced lake-level fluctuations and rapid ecosystem reorganization in response to LIA climatic deterioration. Our results imply that temperature shifts of 1–2°C, when accompanied by major changes in moisture balance, can greatly alter high-altitudinal terrestrial, wetland, and aquatic ecosystems, including conversion between boreal-forest tree line and tundra. The climatic and ecosystem variations in our study area appear to be coherent with changes in solar irradiance, suggesting that changes in solar activity contributed to the environmental instability of the past 700 years.en_GB
dc.identifier.citationEcology, 2008, Vol. 89, Issue 3, pp. 729 - 743en_GB
dc.identifier.urihttp://hdl.handle.net/10871/13953
dc.language.isoenen_GB
dc.publisherEcological Society of Americaen_GB
dc.titleA 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaskaen_GB
dc.typeArticleen_GB
dc.date.available2013-11-15T13:24:23Z
dc.identifier.issn0012-9658
dc.descriptionCopyright by the Ecological Society of America © 2008. Willy Tinner, Christian Bigler, Sharon Gedye, Irene Gregory-Eaves, Richard T. Jones, Petra Kaltenrieder, Urs Krähenbühl, and Feng Sheng Hu 2008. A 700-YEAR PALEOECOLOGICAL RECORD OF BOREAL ECOSYSTEM RESPONSES TO CLIMATIC VARIATION FROM ALASKA. Ecology 89:729–743. http://dx.doi.org/10.1890/06-1420.1en_GB
dc.identifier.journalEcologyen_GB


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