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TitleIsotopes of lakeshore black spruce trees as proxy for Northern Quebec paleoclimate?
AuthorNaulier, M; Savard, M M; Bégin, C; Arsenault, D; Bégin, Y
SourceArcticNet (ASM2012), programme; 2012 p. 158-159
Alt SeriesEarth Sciences Sector, Contribution Series 20120243
Meeting8e réunion scientifique annuelle d'ArcticNet (ASM2012); Vancouver; CA; December 10-14, 2012
Mediapaper; on-line; digital
File formatpdf
AreaQuebec-Labrador Peninsula
Subjectsenvironmental geology; paleontology; isotopes; stable isotope studies; dendrochronology; vegetation; carbon isotopes; climate change
ProgramCoal & Oil Resources Environmental Sustainability, Environmental Geoscience
LinksOnline - En ligne
AbstractKnowledge of past variations in regional climate registered in natural archives contributes to a better understanding of current global climate change. Trees represent one of the best archives because stable isotopes in their rings can record climatic conditions prevailing during their yearly growth. Currently there is no isotopic millennial dendrochronological series existing for the North American boreal forest, but there is a need for such a longterm perspective. In northern Quebec, millennial tree-ring series can be constructed from sub-fossil stems preserved in the littoral zone of lakes. Such tree remains have fallen from the riparian forest after breaking at variable stem heights and collapsing on lake floors. Because tree remains generally contains less than 200 tree rings, the development of a millennial series requires crossdating several tree remains. However, the capacity of such tree from lakeshore trees to contain a meaningful and significant isotopic response to past climate variations has never been investigated. This is the main objective of the present study. Series of 130 tree ring (time period of 1880 to 2010) have been collected systematically at stem heights of 100 and 380cm in each of four black spruce trees (Picea mariana [Mill] B.S.P) on the shore of a lake in the central part of the Quebec-Labrador Peninsula. These eight series are used to verify if the carbon and oxygen isotopic values in cellulose show significant correlations with measured climatic parameters. We have compared isotope series between heights for each trees, then using the mean series from the four trees of each height. In both cases, the carbon isotopes series show much stronger correlations than the oxygen isotope series. We have then assessed the correlations of regional climatic parameters with isotopic means, combining the two heights and the four trees. The compiled and harmonized climate data come from three weather stations (Schefferville, Wabush Lake, Nitchequon) located in the broad region of the selected lake. We have analyzed the correlations (Pearson coefficient and response functions) between the isotope ratios and several climatic parameters such as temperature, precipitation, climatic index (combination of precipitation and mean temperature), watershed inflow, etc., for individual months or their combinations. Again, the carbon isotopic mean series is more strongly correlated with climatic variables than the oxygen ratio, and the climatic index for spring months is the parameter standing out with the strongest correlations. These preliminary results suggest two important points: (1) the isotopic series from different heights correlate significantly, allowing the combination of stem segments from various heights for isotopic studies; (2) the carbon isotopes seem to represent the best isotopic indicator for climatic reconstruction if lakeshore trees are to be used for millennial studies.