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TitleRelevance of using whole-ring stable isotopes of black spruce trees in the perspective of climate reconstruction
AuthorAlvarez, C; Bégin, C; Savard, M M; Dinis, L; Marion, J; Smirnoff, A; Bégin, Y
SourceDendrochronologia vol. 50, 2018 p. 64-69,
Alt SeriesNatural Resources Canada, Contribution Series 20170328
Mediapaper; on-line; digital
File formatpdf; html
ProvinceNewfoundland and Labrador
NTS13B; 13C; 13F; 13G; 13J; 13K
AreaLabrador; Churchill River; Lake Melville; Happy Valley-Goose Bay
Lat/Long WENS -62.0000 -58.0000 55.0000 52.0000
Subjectsenvironmental geology; mathematical and computational geology; geochronology; dendrochronology; climatology; stable isotope studies; carbon isotopes; oxygen isotopes; statistical analyses; temperature; hydrologic properties; surface waters; rivers; discharge rates; Churchill River Basin; methodology; climate reconstruction; trees; black spruce; tree rings; whole-ring cellulose
Illustrationslocation maps; bar graphs; tables; time series; scatter diagrams
ProgramEssential Climate Variable Monitoring, Climate Change Geoscience
AbstractStudies in dendroisotope chemistry suggested that latewood cellulose contains better climatic records than whole-ring cellulose. However, this approach has never been tested on northeastern Canadian spruce trees. This study compares dendroisotopic series of cellulose from late and whole ring, and analyses their statistical relationships with hydro-climatic variables with the aim of selecting the best suited protocol for future hydro-climatic reconstruction in the downstream sector of Churchill River basin of Labrador, Canada. To this end, delta-13C and delta-18O series from latewood (LW) and whole ring (WR) alpha-cellulose of black spruce trees (Picea mariana [Mill.] B.S.P.) were produced for the 1940-2010 period. The results show strong correlations between LW and WR isotopic series suggesting that there are no important variation in the isotopic ratios during the growing year and that black spruce trees use photosynthates of the current growing season to form their earlywood. Moreover, LW and WR delta-13C and delta-18O show similar relationships with both maximum temperature (Tmax) and Churchill River discharge. Correlations are higher when combining delta-13C and delta-18O for LW and WR. Overall, those correlations support the indirect relationship between tree-ring isotopic series and river discharge, as they are integrators of several climatic variables and derived parameters (Tmax, relative humidity, evapotranspiration, etc.). The LW and WR isotopic series give similar statistical relationships with hydro-climatic variables, and the WR treatment is faster (separation easier compared to LW). Thus, for black spruce the use of combined isotopic series in WR can be favored over LW for hydro-climatic reconstruction in the study region.
Summary(Plain Language Summary, not published)
In order to produce the best climatic reconstructions from carbon and oxygen isotopic values of tree-rings, we tested whether it was better to analyze only the final part of the ring (latewood) rather than the entire ring (total ring). Indeed, some studies have shown that it is better to use only the latewood in paleoclimatic studies since the initial part of the ring (earlywood) would be constituted from the reserves produced at the end of the previous year, which induces a bias in the climatic signal of the current tree ring. Our results showed that there are no significant variations in isotope ratios during the growing season and that the two studied parts of the ring have the same climate signals. In the case of black spruce in northeastern Canada, it does not appear necessary to specifically use the latewood part of tree-rings in dendroisotopic studies devoted to climate reconstructions.