Alpine Holocene tree-ring dataset: age-related trends in the stable isotopes of cellulose show species-specific patterns
Authors:Arosio, TitoZiehmer, Malin M.Nicolussi, KurtSchluchter, ChristianLeuenberger, Markus
Source:BIOGEOSCIENCES
Volume:17
Published:2020
Document Type:Article
Abstract:Stable isotopes in tree-ring cellulose are important tools for climatic reconstructions even though their interpretation could be challenging due to nonclimate signals, primarily those related to tree aging. Previous studies on the presence of tree-age-related trends during juvenile as well as adult growth phases in delta D, delta O-18, and delta C-13 time series yielded variable results that are not coherent among different plant species. We analyzed possible trends in the extracted cellulose of tree rings of 85 larch trees and 119 cembran pine trees, i.e., in samples of one deciduous and one evergreen conifer species collected at the tree line in the Alps, covering nearly the whole Holocene. The age trend analyses of all tree-ring variables were conducted on the basis of mean curves established by averaging the cambial-age-aligned tree series. For cambial ages over 100 years, our results prove the absence of any age-related effect in the delta D, delta O-18, and delta C-13 time series for both the evergreen and the deciduous conifer species, with the only exception being larch delta D. However, for lower cambial ages, we found trends that differ for each isotope and species; i.e., mean delta C-13 values in larch do not vary with aging and can be used without detrending, whereas those in cembran pine show a juvenile effect, and the data should be detrended. Mean delta O-18 values present two distinct aging phases for both species, complicating detrending. Similarly, mean delta D values in larch change in the first 50 years, whereas cembran pine changes between 50 and 100 years. Values for these two periods of cambial age for delta D and delta O-18 should be used with caution for climatic reconstructions, ideally complemented by additional information regarding mechanisms for these trends.
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Reprint Address:Arosio, T (corresponding author), Univ Bern, Phys Inst, Climate & Environm Phys, CH-3012 Bern, Switzerland.; Arosio, T (corresponding author), Univ Bern, Oeschger Ctr Climate Change Res, CH-3012 Bern, Switzerland.
Addresses:[Arosio, Tito; Ziehmer, Malin M.; Leuenberger, Markus] Univ Bern, Phys Inst, Climate & Environm Phys, CH-3012 Bern, Switzerland. [Arosio, Tito; Ziehmer, Malin M.; Schluchter, Christian; Leuenberger, Markus] Univ Bern, Oeschger Ctr Climate Change Res, CH-3012 Bern, Switzerland. [Nicolussi, Kurt] Univ Innsbruck, Dept Geog, A-6020 Innsbruck, Austria. [Schluchter, Christian] Univ Bern, Inst Geol Sci, CH-3012 Bern, Switzerland. [Ziehmer, Malin M.] Swiss Trop & Publ Hlth Inst, Socinstr 57, CH-4051 Basel, Switzerland.
E-mail Addresses:tito.arosio@climate.unibe.ch