Relevance of using whole-ring stable isotopes of black spruce trees in the perspective of climate reconstruction.

• Published in: Dendrochronologia
• Main Authors: Alvarez, Cristian, Bégin, Christian, Savard, Martine M., Dinis, Lauriane, Marion, Joëlle, Smirnoff, Anna, Bégin, Yves
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2018
• Subjects: carbon isotopes; oxygen isotopes; latewood; whole ring; black spruce; Labrador; Canada; Churchill River
• Online Access: https://espace.inrs.ca/id/eprint/7733/; https://doi.org/10.1016/j.dendro.2018.05.004

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue dans le document original. Studies 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, δ13C and δ18O series from latewood (LW) and whole ring (WR) α-cellulose of black sprucetrees (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 δ13C and δ18O show similar relationships with both maximum temperature (Tmax) and Churchill River discharge. Correlations are higher when combining δ13C and δ18O 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.