A 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaska

Tinner, Willy; Bigler, Christian; Gedye, Sharon; Gregory-Eaves, Irene; Jones, Richard; Boltshauser-Kaltenrieder, Petra; Krähenbühl, Urs; Hu, Feng Sheng (2008). A 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaska. Ecology, 89(3), pp. 729-743. Washington, D.C.: Ecological Society of America 10.1890/06-1420.1

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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. uctuations. Pollen, diatom, charcoal, macrofossil, and magnetic analyses provide the first continuous record of vegetation -. re - 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. re 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. uctuations and rapid ecosystem reorganization in response to LIA climatic deterioration. Our results imply that temperature shifts of 1 - 2 degrees 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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Palaeoecology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Tinner, Willy; Boltshauser-Kaltenrieder, Petra and Krähenbühl, Urs

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0012-9658

Publisher:

Ecological Society of America

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

04 Oct 2013 15:09

Last Modified:

13 Jun 2014 15:02

Publisher DOI:

10.1890/06-1420.1

Web of Science ID:

000254678200014

URI:

https://boris.unibe.ch/id/eprint/30443 (FactScience: 194461)

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