Evaluation of the non-climatic (age-related) trends of stable oxygen and carbon isotopes in Swiss stone pine (Pinus cembra L.) tree rings from the Eastern Carpathians, Romania

• Published in: Dendrochronologia (Verona) Vol. 78; p. 126061
• Main Authors: Kern, Zoltan, Nagavciuc, Viorica, Hatvani, István Gábor, Hegyi, István Norbert, Loader, Neil J., Popa, Ionel
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 01.04.2023
• Subjects: Age trend; Arolla pine; carbon; Carpathian region; cellulose; climate; data collection; domain; germination; growth rings; isotopes; new species; ontogeny; oxygen; paleoclimatology; Pinus cembra; Romania; sample size; Timberline forest; time series analysis; Tree ring; trees; δ13C; δ18O; Carpathian region; Romania; δ13C; Arolla pine; Tree ring; Timberline forest; δ18O; Age trend
• ISSN: 1125-7865; 1612-0051
• DOI: 10.1016/j.dendro.2023.126061

The presence, magnitude, and duration of age and/or size-related trends in the stable isotopes in tree-ring cellulose time series has been a subject of scientific debate. Where present, their evaluation and removal are key to the development of robust climate calibrations and reconstructions, especially in the low-frequency domain and where sample replication levels are low. Where reported, results suggest that the age/size/height-related trend of stable oxygen (δ18O) and carbon (δ13C) isotope compositions in tree-ring cellulose may vary according to the tree species and the individual tree location. For this reason, it is important when developing long palaeoclimate reconstructions for a new species, geographical region or ecological setting to perform studies to investigate non-climatic (age-related) trends. This study evaluates the ontogenetic pattern in the δ18O and δ13C data in Swiss stone pine trees from the Eastern Carpathians, Romania. For this, we used a new multi-centennial dataset consisting of 5 living and 10 relict Swiss stone pine samples collected from the Eastern Carpathians, which were annually resolved for δ18O and δ13C composition. Age-related trends were evaluated using the conventional “slope of the mean” approach as well as the “mean of the slope” method. The results suggest that neither the traditional “slope-of-the mean” nor the “mean-of-the-slope” approach indicates a persistent linear trend in the Swiss stone pine δ18O data, while for the δ13C data a systematic enrichment in 13C was observed over a < 40 year-long period after germination. Despite the limited sample size of this developing dataset these findings help to inform more detailed analyses and future sampling strategies in the Eastern Carpathian Swiss stone pine stands. •Are there a systematic age-trend in δ13C or δ18O variance in Pinus cembra tree rings?•A Carpathian dataset consisting of 5 living and 10 relict samples is studied.•There is no overall linear trend in the Swiss stone pine δ18O data.•The δ13C data showed an enrichment in 13C over a < 40 year-long juvenile period.