Climatic signals in stable carbon isotope ratios of Juniper and Oak tree rings from northern Iran

Foroozan Z, Pourtahmasi K, Bräuning A (2018)

Publication Status: Published

Publication Type: Journal article

Publication year: 2018



Book Volume: 165

Pages Range: 90-99

DOI: 10.1016/j.gloplacha.2018.03.010


Stable isotope ratios in tree rings are increasingly used as palaeoclimatic archive and ecophysiological indicator. We used cross-dated tree-ring series from different tree functional types, i.e. the evergreen conifer Jmiperus polycarpus and the deciduous broadleaved Quercus macranthera. The samples were collected from Chaharbagh Gorgon forest in northern Iran, where oaks and junipers grow on north-facing and south-facing slopes, respectively. We extracted a-cellulose from the whole wood of annually separated tree rings and evaluated their potential for palaeoclimate reconstructions by examining the relationships between variations of delta C-13 in treering cellulose and climate parameters. Based on tree-ring delta C-13, we calculated intrinsic water use efficiency (iWUE) and evaluated changes in water availability at the study site over the past 50 years. We found significant negative relationships between tree-ring delta C-13 values in oak and juniper and precipitation in April and spring (only in junipers), while no significant correlations of tree-ring delta C-13 with temperature occurred. A strong negative relationship between tree-ring delta C-13 and summer Palmer Drought Severity Index (PDSI) was found at the drier site, indicating that juniper growing on south-facing slopes is a better indicator of drought stress in semiarid environments. A continuous increase in iWUE in both species was observed. delta C-13 variations in both species reflect the combined influence of climate and local site conditions. The interplay between climatic conditions and species behavior determines the inter-annual delta C-,C-3 patterns of oak and juniper trees. Due to its more enriched mean delta C-13 (i.e., less negative average delta C-I3) and its higher climatic sensitivity, juniper is a more suitable proxy for paleoclimatic reconstructions in northern Iran.

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Foroozan, Z., Pourtahmasi, K., & Bräuning, A. (2018). Climatic signals in stable carbon isotope ratios of Juniper and Oak tree rings from northern Iran. Global and Planetary Change, 165, 90-99.


Foroozan, Zeynab, Kambiz Pourtahmasi, and Achim Bräuning. "Climatic signals in stable carbon isotope ratios of Juniper and Oak tree rings from northern Iran." Global and Planetary Change 165 (2018): 90-99.

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