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Oxygen Isotope Compositions of Cellulose in Earlywood of Larix cajanderi Determined by Water Source Rather Than Leaf Water Enrichment in a Permafrost Ecosystem, Eastern Siberia
Author(s) -
Fan R.,
Shimada H.,
Tei S.,
Maximov T. C.,
Sugimoto A.
Publication year - 2021
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2020jg006125
Subject(s) - larch , permafrost , precipitation , cellulose , latitude , isotopes of oxygen , taiga , environmental science , dendrochronology , soil water , environmental chemistry , water content , chemistry , ecology , biology , soil science , geology , geography , paleontology , geotechnical engineering , organic chemistry , geodesy , meteorology , nuclear chemistry
The oxygen isotopic composition of tree‐ring cellulose (δ 18 O cell ) has been widely used to reconstruct historical environmental changes; however, the control factors on δ 18 O cell have not been fully constrained—especially in high latitudes. To evaluate the influence of metabolic processes and related environmental factors on δ 18 O cell , we analyzed the δ 18 O values of soil water (1998–2015), stem water (1997–2016), leaf water (3 days in each 2014 and 2015), and tree‐ring cellulose (1981–2016), on a dominant larch species ( Larix cajanderi ) in an eastern Siberian boreal forest. We determined that the δ 18 O variability of water sources is dependent on the precipitation, and the 18 O enrichment in leaf water is determined by relative humidity. These findings suggest that both water source uptake and leaf water enrichment processes can affect the δ 18 O values of oxygen‐containing compounds in larch trees in the study site. However, the δ 18 O cell (one of the end oxygen‐containing products) was found dependent on water sources on which was related to the amount of summer rainfall in the previous year. This finding significantly differs from that of studies in other areas, which infer the positive correlation between δ 18 O cell and leaf water enrichment rather than precipitation or water sources. These differences are predominantly due to the specific conditions of high‐latitude areas, such as the large seasonal δ 18 O difference in precipitation, the existence of permafrost, and the low growth rate. Our findings contribute toward the development of tree‐ring paleoclimate reconstructions—especially in eastern Siberia.