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TitleAssessing tree-ring carbon and oxygen stable isotopes for climate reconstruction in the Canadian northeastern boreal forest
AuthorBégin, C; Gingras, M; Savard, M M; Marion, J; Nicault, A; Bégin, Y
SourcePalaeogeography, Palaeoclimatology, Palaeoecology vol. 423, 2015 p. 91-101,
Alt SeriesEarth Sciences Sector, Contribution Series 20130339
Mediapaper; on-line; digital
File formatpdf
NTS23F/13; 23K/04; 23E/16; 23L/01
AreaSchefferville; Nichequon; Wabush; Reservoir Caniapiscau
Lat/Long WENS -72.0000 -67.0000 56.0000 52.0000
Subjectsgeochemistry; Nature and Environment; isotopic studies; oxygen isotopes; carbon isotopes; temperature; dendroclimatology; boreal forest; tree-rings; temperature reconstruction
Illustrationslocation maps; graphs; plots; tables
ProgramCoal & Oil Resources Environmental Sustainability, Environmental Geoscience
AbstractIn this study, we analyzed stable isotopes of oxygen (delta18O) and carbon (delta13C) of five black spruce (Picea mariana (Mill.) BSP) trees growing in the Québec boreal forest.We then produced the first dendroisotopic series covering the last two centuries (1800 - 2003) for this region where climatic records are particularly scarce and of short duration. Our aim was to evaluate the isotope sensitivity to climate and their potential as proxies for past climate conditions. The delta18O results showa strong coherence between all trees indicating that these values express a homogenous response at the site scale. For the delta13C series, slight inter-tree differences suggest the influence of micro-site conditions. Isotopic valueswere compared to climatic data for the period 1944 - 2003. These statistical analyses indicate that the delta13C and delta18O ratios are directly influenced by summer maximum temperatures but also correlate with parameters that integrate temperatures and moisture status. In all cases, the climate effects on delta13C values areweaker than the ones recorded by the delta18O series. Moreover, because the delta18O and delta13C values are sensitive to climatic variables that are linked and commonly associated in typical subarctic climate ambiances (warm-dry, cold-wet), the patterns of their joint response show stronger correlations with climatic parameters. Then, a temperature reconstruction was developed based on a regression model that calibrates the combined
delta13C and delta18O series against summer maximum temperature (TmaxJJA). The reconstructed summer temperatures indicates that the first half of the 19th centurywas the coldest period in the past 200 years and that a steadily change throughout milder conditions started in the early 1940's. These trends are consistent with other reconstructed values from independent proxies available for the same region. This research confirms that C and O dendroisotopic series of black spruce trees in high latitudes can document adequately past climatic
Summary(Plain Language Summary, not published)
Stable isotopes of some elements such as carbon and oxygen in tree rings are increasingly considered as good indicators of environmental conditions and anthropogenic impacts in forest ecosystems. An important part of this approach is based on the separation of isotopic signals related to the pollution from those related to natural conditions, especially climatic. The first step is to identify the climatic parameters that best explain the variations in isotopic values under natural conditions and for the same tree species used in pollution studies. We then explore the climatic significance of isotopic series produced in one natural site in the Canadian boreal forest.