ALBERT

Beschreibung:    Tundra and taiga ecosystems comprise nearly 40 % of the terrestrial landscapes of Canada. These permafrost ecosystems have supported humans for more than 4500 years, and are currently home to ca. 115,000 people, the majority of whom are First Nations, Inuit and Métis. The responses of these ecosystems to the regional warming over the past 30–50 years were the focus of four Canadian IPY projects. Northern residents and researchers reported changes in climate and weather patterns and noted shifts in vegetation and other environmental variables. In forest-tundra areas tree growth and reproductive effort correlated with temperature, but seedling establishment was often hindered by other factors resulting in site-specific responses. Increased shrub cover has occurred in sites across the Arctic at the plot and landscape scale, and this was supported by results from experimental warming. Experimental warming increased vegetation cover and nutrient availability in most tundra soils; however, resistance to warming was also found. Soil microbial diversity in tundra was no different than in other biomes, although there were shifts in mycorrhizal diversity in warming experiments. All sites measured were sinks for carbon during the growing season, with expected seasonal and latitudinal patterns. Modeled responses of a mesic tundra system to climate change showed that the sink status will likely continue for the next 50–100 years, after which these tundra systems will likely become a net source of carbon dioxide to the atmosphere. These IPY studies were the first comprehensive assessment of the state and change in Canadian northern terrestrial ecosystems and showed that the inherent variability in these systems is reflected in their site-specific responses to changes in climate. They also showed the importance of using local traditional knowledge and science, and provided extensive data sets, sites and researchers needed to study and manage the inevitable changes in the Canadian North. Content Type Journal Article Pages 1-28 DOI 10.1007/s10584-012-0587-1 Authors Gregory H. R. Henry, Department of Geography, University of British Columbia, Vancouver, BC V6T 1Z2, Canada Karen A. Harper, School for Resource and Environmental Studies, Dalhousie University, Halifax, NS B3H 4R2, Canada Wenjun Chen, Canadian Centre for Remote Sensing, Natural Resources Canada, Ottawa, ON K1A 0Y7, Canada Julie R. Deslippe, Department of Forest Science, University of British Columbia, Vancouver, BC V6T 1Z4, Canada Robert F. Grant, Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2E3, Canada Peter M. Lafleur, Department of Geography, Trent University, Peterborough, ON K9J 7B8, Canada Esther Lévesque, Département de chimie-biologie, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada Steven D. Siciliano, Department of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada Suzanne W. Simard, Department of Forest Science, University of British Columbia, Vancouver, BC V6T 1Z4, Canada Journal Climatic Change Online ISSN 1573-1480 Print ISSN 0165-0009