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

Abstract

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.,

Impact of Climate Change on Hunter‐Fisher‐Gatherer Cultures in Northern Japan Over the Past 4,400 Years

“…If relative humidity was the dominant factor determining Sphagnum δ 18 O, the correlation between Sphagnum δ 18 O and Δδ 18 O vp–sp should be positive. However, Sphagnum δ 18 O was inversely correlated with Δδ 18 O vp–sp at the MHWL sites (Figure S5 in the Supporting Information ), which means that Sphagnum δ 18 O mainly reflected the δ 18 O of precipitated water rather than the effect of relative humidity, because the fractionation of Sphagnum water δ 18 O is limited (Jones et al., 2019; Nichols et al., 2010; Sakurai et al., 2021).…”

“…However, the degree of evapotranspiration is greater in vascular plants (Jones et al., 2019; Nichols et al., 2010), resulting in a larger difference of δ 18 O between vascular plants and Sphagnum (Δδ 18 O vp–sp ) under low relative humidity conditions. In the Bekanbeushi moor, since both Sphagnum and vascular plants use the same water source, pore water in the acrotelm layer (Sakurai et al., 2021), Δδ 18 O vp–sp was regarded as a potential proxy of relative humidity (Sakurai et al., 2021). Because the Minamihama moor at the MHWL sites is an ombrotrophic bog (precipitation‐fed peatland) covered with Sphagnum and has the same hydrological conditions as the Bekanbeishi moor, we assumed that the Δδ 18 O vp–sp reflects relative humidity in the Minamihama moor.…”

“…Median values were used for the creation of the age-depth model. Cellulose was separated and purified from the homogenized tissue fraction according to the procedure of Sakurai et al (2021). Analysis of cellulose oxygen isotopes was conducted using a continuous flow pyrolysis elemental analyzer/isotope mass spectrometer (TCEA/Delta plus XL).…”

“…On the other hand, the spatial distributions of the Zoku-Jomon, Satsumon, and Ainu cultures (inland cultures) stayed in Hokkaido Island, although the northern and southern margins shifted latitudinally (Figure 4). The KH-84-3-9, KH-84-3-33, KH-86-2-9, D-GC-6 (Koizumi et al, 2006), and HO76-P1 (Shimada et al, 2004), (e) moving correlation coefficient of the 1000-year window of variations between Sphagnum δ 18 O at MHLW-1 and Fragilariopsis doliolus abundance at D-GC-6 (resampled at 100-year interval), (f) the cellulose δ 18 O values of Sphagnum, (g) the difference of δ 18 O between grass leaf and Sphagnum (Δδ 18 O vp-sp ) in core BKB-2 (Sakurai et al, 2021), and (h) U K 37 ′-based sea surface temperature in cores MD01-2,421 (Isono et al, 2009) and PC-6 (Minoshima et al, 2007). The bars indicate 1σ intervals.…”

“…Precipitation‐fed peatlands in Hokkaido contain continuous accumulations of Sphagnum , which are shown to be excellent archives of precipitated water δ 18 O. The δ 18 O values of the cellulose and organic matter are potentially useful 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; Sakurai et al., 2021). Recently, Sakurai et al.…”