Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Potential Arctic Terrestrial Ecosystem Feedbacks to Climate Change: A Consideration of Component Carbon Pool Dynamics
Paul Grogan1, Sven Jonasson2
1Biology, Queen's University, Biosciences complex, Kingston, ON, K7L 3N6, Canada, Phone 613-533-6152, Fax 613-533-6617, groganp@biology.queensu.ca
2Botanisk Institut, University of Copenhagen, Oster Farimagsgade 2D, Copenhagen K, DK 1353, Denmark, Phone 453-532-2268, Fax 453-532-2321, svenj@bot.ku.dk
Arctic and boreal forest ecosystems are important in the context of global climate change because their soils contain extensive organic carbon (C) reserves, and because they are expected to undergo the most rapid increases in temperature. Most experimental and C modeling research in these ecosystems has been focused on summertime biogeochemical processes. Here, we report an experimental manipulation study aimed at characterizing the controls on the annual patterns of gross CO2 production in two common Swedish sub-arctic ecosystems. Our results indicate that the removal of plants and their current year’s litter significantly reduced the sensitivity of gross respiration to intra-annual variations in soil temperature for both heath and birch understory ecosystems. We conclude that respiration from soil organic matter C stores in these ecosystems is less temperature responsive than respiration derived from recent plant C fixation. Furthermore, the amount of substrate being respired was significantly higher in the birch understory. Finally, our results suggest that respiration derived from accumulated bulk soil organic matter constitutes about half of total ecosystem CO2 production during winter. Accurate assessment of the potential for positive feedbacks from high latitude ecosystems to CO2-induced climate change will require the development of physiological models of net ecosystem C exchange that account for such differences in temperature sensitivity between C pools and substrate respiratory coefficients between vegetation-types, and that integrate over summer and winter seasons.
Abstract Categories: Biological Feedbacks
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