A network of 54 ring-width chronologies is used to estimate changes in summer climate within the Winnipeg River basin, Canada, since AD 1783. The basin drains parts of northwestern Ontario, northern Minnesota and southeastern Manitoba, and is a key area for hydroelectric power production. Most chronologies were developed from Pinus resinosa and P. strobus, with a limited number of Thuja occidentalis, Picea glauca and Pinus banksiana. The dominant pattern of regional tree growth can be recovered using only the nine longest chronologies, and is not affected by the method used to remove variability related to age or stand dynamics from individual trees. Tree growth is significantly, but weakly, correlated with both temperature (negatively) and precipitation (positively) during summer. Simulated ring-width chronologies produced by a process model of tree-ring growth exhibit similar relationships with summer climate. High and low growth across the region is associated with cool/wet and warm/dry summers, respectively; this relationship is supported by comparisons with archival records from early 19th century fur-trading posts. The tree-ring record indicates that summer droughts were more persistent in the 19th and late 18th century, but there is no evidence that drought was more extreme prior to the onset of direct monitoring. Crown
|Original language||English (US)|
|Number of pages||15|
|State||Published - Sep 2008|
Bibliographical noteFunding Information:
We thank J. Balmat, E. Nielsen and the staff at the Manitoba Geological Survey for field support, and J. Rowland and E. Margolis for laboratory assistance. Manitoba Conservation, the Ontario Ministry of Natural Resources and the Greenwood Lake Nature Reserve granted permission to collect samples within their respective jurisdictions. We thank M. Girardin for contributing his data from northwestern Ontario, T. Ault for computing assistance, E. Vaganov for providing access to the Vaganov Shashkin model, and K. Anchukaitis for his guidance in employing the model within Matlab. We are grateful to D. Fisher, P. Bartlein and two anonymous reviewers for reviewing this manuscript prior to publication. Financial support for this research was provided by Manitoba Hydro, the Manitoba Geological Survey, the Prairie Adaptation Research Collaborative and the Natural Sciences and Engineering Research Council of Canada. This manuscript is ESS contribution number 20060728.
Copyright 2011 Elsevier B.V., All rights reserved.
- Northwestern Ontario
- Vaganov-Shashkin model
- Winnipeg River