Effects of age and environment on stable carbon isotope ratios in tree rings of riparian Populus

Palaeogeography, Palaeoclimatology, Palaeoecology
By: , and 



Stable carbon isotopes of riparian tree rings are enabling improved reconstruction of past climate variability, but this advance is limited by difficulty distinguishing the effects of tree age from those of climate. We investigated relative influence of age and climate trends in genus Populus, which dominates floodplain forests in Europe, Asia and North America. We related precipitation and river flow to annual variation in stable carbon isotope ratio (δ13C) in trees with a broad distribution of ages spanning two hundred years. On the floodplain of the lightly regulated Little Missouri River, North Dakota, USA, we examined a total of 845 rings from seven specimens of cottonwood tree (Populus deltoides W. Bartram ex Marshall ssp. monilifera [Aiton] Eckenwalder). Cottonwood δ13C decreased from pith to bark in whole wood, but this trend was almost completely eliminated in purified cellulose. The δ13C offset between whole wood and cellulose increased from pith to bark, consistent with trends of decreasing cellulose and increasing hemicellulose as a proportion of whole wood. While annual ring width was correlated with monthly precipitation from April through June, δ13C showed strong correlations only in June and July, suggesting that these complementary proxies allow resolution of seasonal variation in water availability. We conclude that past climate can be reconstructed from δ13C of purified cellulose from cottonwood without detrending for tree age.
Publication type Article
Publication Subtype Journal Article
Title Effects of age and environment on stable carbon isotope ratios in tree rings of riparian Populus
Series title Palaeogeography, Palaeoclimatology, Palaeoecology
DOI 10.1016/j.palaeo.2019.03.022
Volume 524
Year Published 2019
Language English
Publisher Elsevier
Contributing office(s) Fort Collins Science Center
Description 8 p.
First page 25
Last page 32
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