A 2600-year summer climate reconstruction in central Japan by integrating tree-ring stable oxygen and hydrogen isotopes

Abstract

Abstract. Oxygen isotope ratios (δ18O) of tree-ring cellulose are a novel proxy for summer hydroclimate in monsoonal Asia. In central Japan, we collected 67 conifer wood samples, mainly Chamaecyparis obtusa, with ages encompassing the past 2600 years. The samples were taken from living trees, archeological wood, architectural wood, and buried logs. We analyzed stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in tree-ring cellulose in these samples (more than 15 000 rings in total) without using a pooling method and constructed a statistically reliable tree-ring cellulose δ18O time series for the past 2500 years. However, there were distinct age trends and level offsets in the δ18O record, and cellulose δ18O values showed a gradual decrease as an individual tree matures. This suggested it is difficult to establish a cellulose δ18O chronology for low-frequency signals by simple averaging of all the δ18O time series data. In addition, there were opposite age trends in the cellulose δ2H, and δ2H gradually increased with tree age. There were clear positive correlations in the short-periodicity variations between δ18O and δ2H, probably indicating a common climate signal. A comparison of the δ18O and δ2H time series in individual trees with tree-ring width suggested that the opposite age trends of δ18O and δ2H are caused by temporal changes in the degree of post-photosynthetic isotope exchange with xylem water (physiological effect), accompanied by changes in stem growth rate that are influenced by human activity in the forests of central Japan. Based on the assumptions that cellulose δ18O and δ2H vary positively and negatively with constant proportional coefficients due to climatological and physiological effects, respectively, we solved simultaneous equations for the climatological and physiological components of variations in tree-ring cellulose δ18O and δ2H in order to remove the age trend. This enabled us to evaluate the climatic record from cellulose δ18O variations. The extracted climatological component in the cellulose δ18O for the past 2600 years in central Japan was well correlated with numerous instrumental, historical, and paleoclimatological records of past summer climate at various spatial and temporal scales. This indicates that integration of tree-ring cellulose δ18O and δ2H data is a promising method to reconstruct past summer climate variations on annual to millennial timescales, irrespective of the growth environment. However, analytical and statistical methods need to be improved for further development of this climate proxy.

A high‐temperature water vapor equilibration method to determine non‐exchangeable hydrogen isotope ratios of sugar, starch and cellulose

“…Various high‐throughput methods have been developed to study the carbon and oxygen isotopic composition of non‐structural plant carbohydrates (NSC; i.e., sugar and starch) (Lehmann et al, 2020; Richter et al, 2009; Wanek, Heintel, & Richter, 2001), and of structural carbohydrates such as tree‐ring or leaf cellulose (Boettger et al, 2007). In contrast, methods to investigate the non‐exchangeable hydrogen isotopic composition (δ 2 H ne ) in plant carbohydrates are still mainly limited to cellulose (An et al, 2014; Arosio, Ziehmer, Nicolussi, Schlüchter, & Leuenberger, 2020; Epstein, Yapp, & Hall, 1976; Filot, Leuenberger, Pazdur, & Boettger, 2006; Mischel, Esper, Keppler, Greule, & Werner, 2015; Nakatsuka et al, 2020; Sauer, Schimmelmann, Sessions, & Topalov, 2009; Xia et al, 2020). Existing methods to analyse δ 2 H ne values of NSC use site‐specific natural isotope fractionation nuclear magnetic resonance spectroscopy (NMR) or sample derivatization prior to isotope ratio mass spectrometry (IRMS) (Abrahim, Cannavan, & Kelly, 2020; Augusti, Betson, & Schleucher, 2008; Dunbar & Schmidt, 1984; Schleucher, Vanderveer, Markley, & Sharkey, 1999; Zhang, Quemerais, Martin, Martin, & Williams, 1994).…”

Cellulose Oxygen Isotopes of Sphagnum and Vascular Plants in a Peat Core Reveal Climate Change in Northern Japan Over the Past 2,000 Years

“…Additionally, high relative humidity decreases transpiration from plants and evaporation from the ground surface, which in turn decreases cellulose δ 18 O (Nakatsuka et al, 2004). Tsuji et al (2008) Tree-ring cellulose δ 18 O in central Honshu, Japan, was positively correlated with summer air temperature and negatively correlated with summer precipitation and relative humidity (Nakatsuka et al, 2020). In contrast to tree-ring results, leaf wax δD at Lake Biwa, central Honshu, exhibited orbital-scale variability with higher δD in warm and humid periods, as supported by the pollen assemblage; in this case, δD was assumed to reflect air temperature (Seki et al, 2012).…”

“…The oxygen isotopic composition of precipitation is sensitive to the atmospheric dynamics (Dansgaard, 1964; Jouzel et al., 1994). Therefore, the tree‐ring cellulose δ 18 O is increasingly used for paleoclimate reconstruction of recent centuries (e.g., Anderson et al., 1998; Epstein et al., 1977; Gray & Thompson, 1977; Nakatsuka et al., 2004, 2020; Roden et al., 1999; Sternberg, 2009; Tsuji et al., 2008). Peat, which has also been extensively investigated in paleoclimate studies, contains Sphagnum and other plant remains, and their cellulose and organic matter δ 18 O values may be used for long‐term climate reconstruction (e.g., Daley et al., 2010, 2016; Hong et al., 2000, 2009; Jones et al., 2014; Kock et al., 2019; Kühl & Moschen, 2012).…”

The Ōshū Fujiwara—An interdisciplinary study on the history, culture and medical assessment of the oldest known mummified human remains in Japan (late Heian, 12th century AD)

“…According to data from the Japan Meteorological Agency, Morioka (the closest larger city from Hiraizumi) had an annual mean temperature of 10.2 C° and relative humidity of 74% between 1981 and 2010 [ 24 ]. Recent paleoclimatological reconstructions for central Japan [ 25 ] show climatic variations since the medieval period comparable to global temperature and East Asian precipitation models, implying a somewhat drier climate during the medieval climate anomaly from about AD 900 to 1200 [ 26 ], followed by a more humid climate during the Little Ice Age from the 16 th to the 19 th centuries [ 25 , 27 ]. Nevertheless, such climatic conditions are still quite far from facilitating natural mummification even with slightly less humidity.…”