Date:7/29/2010

n July, with a growing season of just 60 to 80 days. The northern taiga vegetation is dominated by spruce, pine and birch. The samples came from three locations in the Khibiny Mountains close to recent altitudinal timberline at altitudes of between 250 and 450 m above sea level. The geographical northern timberline lies approximately 100 km further north. In earlier studies, researchers led by Tatjana Bttger from the UFZ were able to show that pine forests on the Kola Peninsula expanded between 7000 and 3500 years ago to about 50 km north of their present-day limit. However, for this study, they used trees from the altitudinal timberline, since they respond very sensitively to temperature fluctuations and provide particularly useful information, as demonstrated by US researchers in November 2009 in the journal PNAS when they used a long-lived species of pine in California and Nevada to show that these trees had grown particularly fast over the last 50 of the past 3500 years because of higher temperatures.

In the Tree-Ring-Laboratory at the University of Hohenheim in Stuttgart the German researchers measured the width of the individual tree rings. The calibration of these data with the help of meteorological records for the last 127 years and the interpretation of results occurred together with Russian Academy of Sciences in Moscow and the Helmholtz Centre for Environmental Research in Halle. "Besides of temperature, growth is also strongly influenced by non-climatic factors like light, nutrients, water supply and competition from other trees. So it is vital to isolate these trends to obtain a climate signal as pure as possible," explains Yury M. Kononov from the Russian Academy of Sciences in Moscow.

Following the summer temperature reconstruction on the Kola Peninsula, the researchers compared their results with similar tree-ring studies from Swedish Lapland and from the Yamal and Taimyr Peninsulas in Russian Siberia, which had been published in Holoce
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Contact: Tilo Arnhold presse@ufz.de 49-341-235-1635 Helmholtz Association of German Research Centres Source:Eurekalert

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