Tree growth and inferred temperature variability at the North American Arctic treeline
We present white spruce (Picea glauca) tree-ring width and maximum latewood density chronologies for two latitudinal treeline sites in northern interior Canada: along the Coppermine River in the Northwest Territories (NWT); and in the Thelon River Sanctuary, Nunavut. These chronologies provide clima...
| Published in: | Global and Planetary Change |
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| Main Authors: | , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
2009
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| Subjects: | |
| Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/tree-growth-and-inferred-temperature-variability-at-the-north-american-arctic-treeline(f97ce57e-1e3d-4fd7-90b2-a05b4b15f173).html https://doi.org/10.1016/j.gloplacha.2008.10.011 |
| Summary: | We present white spruce (Picea glauca) tree-ring width and maximum latewood density chronologies for two latitudinal treeline sites in northern interior Canada: along the Coppermine River in the Northwest Territories (NWT); and in the Thelon River Sanctuary, Nunavut. These chronologies provide climate and tree growth information for these two remote locations, filling a sizeable gap in spatial coverage of proxy records used to reconstruct temperature variability for the Northern Hemisphere. They represent some of the longest high-resolution proxies available for northern North America, dating as far back as AD 1046 for Coppermine ring widths. These chronologies correlate significantly with hemispheric-scale annual temperature reconstructions for the past millennium. Density records from both sites show a positive relationship with warm-season temperature data since similar to the mid-20th century, although this link is somewhat weaker in recent decades (since similar to 1980). Both ring-width chronologies demonstrate even greater loss of temperature sensitivity, and in the Thelon ring-width series a sustained reduction in growth appears linked to increased drought stress in this recent period. Diminishing correlations with temperature are also found when the Thelon ring-width and climate data are prewhitened, indicating that any low frequency uncertainties in the instrumental or tree-ring data (e.g., artifacts from the standardization process) cannot entirely account for this result. Our findings therefore suggest a recent loss of temperature sensitivity at these northern treeline locations that varies with the parameter and site studied. These and other uncertainties in the tree-ring as well as instrumental data will need to be resolved in future efforts to relate northern tree-ring records to temperature variability on a range of spatial scales. (C) 2008 Elsevier B.V. All rights reserved. |
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