Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Global Boreal Forest Responses to Climate Warming
Glenn P. Juday1, Valerie A. Barber2, Eugene A. Vaganov3, Edward Berg4
1Forest Sciences, University of Alaska Fairbanks, P.O. Box 7200, Fairbanks, AK, 99775-7200, USA, Phone 907-474-6717, Fax 907-474-7439, g.juday@uaf.edu
2Forest Sciences, University of Alaska Fairbanks, P.O. Box 7200, Fairbanks, AK, 99775-7200, USA, Phone 907-474-6794, Fax 907-474-6184, ffvab@uaf.edu
3no contact info
4Kenai National Wildlife Refuge, U.S. Fish and Wildlife Service, PO Box 2139, Soldotna, AK, 99669, USA, Phone 907-260-2812, Fax 907-262-3599, edward_berg@fws.gov
The Arctic Climatic Impact Assessment (ACIA) has provided the opportunity to conduct a circumpolar investigation and synthesis of climate warming and the boreal forest including the record of recent climate change, the vulnerability of forest systems to warming, and scenarios of climate change from GCMs. A comprehensive view of the record of forest growth in relation to climate contains apparently contradictory records of opposite temperature trends in different parts of the global boreal forest. These can be explained as a result of an interconnected atmospheric circulation system with coupled regional departures that can be opposite in their temperature effects. The northernmost boreal forest also offers a unique very long record (up to 9000 years) of very high resolution that provides important perspective when examining current climate warming effects. For example, distribution of trees (sparse stands or individuals) extended all the way to the Arctic shore across the entire Russian Arctic during much of the early Holocene as indicated by frozen wood remains in permafrost. Finally, the varied social context is another crucial factor in examining climate-warming effects on forest systems. In Iceland climate warming is producing a more favorable environment for a large-scale afforestation program, in the Nordic countries investments in forest management are at risk, and in much of Siberia, Alaska, and Canada biodiversity resources are the main focus of concern.
A substantial amount of new science supports assessments of the effect of climate warming including the Flakaliden direct warming experiment in Sweden, the IGBP Central Siberian Transect, the BOREAS project, and dendrochronological studies in Alaska. Many tree species in different parts of the northern boreal region display a positive growth response to growing season warmth. Generally these are the more humid parts of the boreal forest in eastern Canada and northern Europe. The Central Siberia transect captures a suite of growth responses across a very large latitudinal gradient, and includes trees and sites with negative responses to warmth because of drought limitations. Strong warming in Alaska has been associated with substantial growth reductions on moisture-limited sites, which are widespread in lowlands. Scenarios of 5 GCMs run through the 21st century have been calibrated to empirical temperature-tree growth records. The scenarios produce climates that would be suitable for substantial increases in individual tree growth in positive-responding tree populations, such as the Tamyir Peninsula and northern Labrador. However, warmth is a critical factor in triggering events for major agents of change in boreal forests, especially fire and insect outbreaks. Warming scenarios also are associated with temperatures that, based on empirical relationships, would not be suitable for the survival of current trees on the landscape.
Abstract Categories: Changes on Land
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