Change search
ReferencesLink to record
Permanent link

Direct link
A 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaska.
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
Show others and affiliations
2008 (English)In: Ecology, ISSN 0012-9658, Vol. 89, no 3, 729-43 p.Article in journal (Refereed) Published
Abstract [en]

Recent 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 1–28C, 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.

Place, publisher, year, edition, pages
2008. Vol. 89, no 3, 729-43 p.
Keyword [en]
Alaska, Climate, Diatoms, Ecosystem, Fires, Forestry, Fossils, Geologic Sediments, Greenhouse Effect, Ice Cover, Plant Physiological Phenomena, Pollen, Time Factors, Trees
URN: urn:nbn:se:umu:diva-11467DOI: doi:10.1890/06-1420.1PubMedID: 18459336OAI: diva2:151138
Available from: 2009-01-09 Created: 2009-01-09 Last updated: 2011-01-10Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Bigler, Christian
By organisation
Ecology and Environmental Science

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 57 hits
ReferencesLink to record
Permanent link

Direct link