Vegetation and Climate Change during the Last Deglaciation in the Great Khingan Mountain, Northeastern China

<div><p>The Great Khingan Mountain range, Northeast China, is located on the northern limit of modern East Asian Summer Monsoon (EASM) and thus highly sensitive to the extension of the EASM from glacial to interglacial modes. Here, we present a high-resolution pollen record covering the last glacial maximum and the early Holocene from a closed crater Lake Moon to reconstruct vegetation history during the glacial-interglacial transition and thus register the evolution of the EASM during the last deglaciation. The vegetation history has gone through distinct changes from subalpine meadow in the last glacial maximum to dry steppe dominated by <i>Artemisia</i> from 20.3 to 17.4 ka BP, subalpine meadow dominated by Cyperaceae and <i>Artemisia</i> between 17.4 and 14.4 ka BP, and forest steppe dominated by <i>Betula</i> and <i>Artemisia</i> after 14.4 ka BP. The pollen-based temperature index demonstrates a gradual warming trend started at around 20.3 ka BP with interruptions of several brief events. Two cold conditions occurred around at 17.2–16.6 ka BP and 12.8–11.8 ka BP, temporally correlating to the Henrich 1 and the Younger Dryas events respectively, 1and abrupt warming events occurred around at 14.4 ka BP and 11.8 ka BP, probably relevant to the beginning of the Bølling-Allerød stages and the Holocene. The pollen-based moisture proxy shows distinct drought condition during the last glacial maximum (20.3–18.0 ka BP) and the Younger Dryas. The climate history based on pollen record of Lake Moon suggests that the regional temperature variability was coherent with the classical climate in the North Atlantic, implying the dominance of the high latitude processes on the EASM evolution from the Last Glacial Maximum (LGM) to early Holocene. The local humidity variability was influenced by the EASM limitedly before the Bølling-Allerød warming, which is mainly controlled by the summer rainfall due to the EASM front covering the Northeast China after that.</p></div

Simplified pollen percentage and concentration diagram of Lake Moon.

<p>Exaggeration (×10) is indicated by light-colored shading (adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.g002" target="_blank">Fig 2</a> of [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref029" target="_blank">29</a>]).</p

Locations of study site and other paleoclimate records in the East Asia.

<p>(map modified from NASA; <a href="http://earthobservatory.nasa.gov/" target="_blank">http://earthobservatory.nasa.gov/</a>) Locations of Lake Moon, Baikal (52°05′N, 105°52′E), Suigetsu (35°35′N, 135°53′E) and Mikata (35°33′N, 135°54′E), and Hulu (32°30′N, 119°10′E) and Maboroshi (34°39′N, 133°13′E) caves with atmospheric circulation in summer. Black arrows show seasonal dominant wind vectors and the red arrow points to the location of coring point of Lake Moon.</p

Averaged monthly precipitation (bars) and air temperatures (circles) in Aershan during AD 1982–2011.

<p>Averaged monthly precipitation (bars) and air temperatures (circles) in Aershan during AD 1982–2011.</p

Comparison of pollen records with the δ¹⁸O records from Greenland ice core and Chinese stalagmite.

<p>(a) The δ¹⁸O records of the Greenland ice cores [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref047" target="_blank">47</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref048" target="_blank">48</a>] (the light blue line is NGRIP δ¹⁸O profile, the dark blue line is GRIP δ¹⁸O profile), (b) the common logarithm transformation of pollen-based Temperature index (to outweigh strong variations caused by percentage maxima of <i>Betula</i> and Cyperaceae), (c) pollen percentages of arboreal (green line), steppe (orange line) and meadow (blue line) taxa, (d) pollen-based Moisture index, (e) the stalagmite δ¹⁸O records from Hulu cave [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref010" target="_blank">10</a>].</p

Age-depth plot of the Moon Lake sequence.

<p>The calibrated AMS ¹⁴C dates using CALIB 6.01 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref026" target="_blank">26</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref027" target="_blank">27</a>] are shown with 2 sigma error bar (adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.g002" target="_blank">Fig 2</a> of [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0146261#pone.0146261.ref022" target="_blank">22</a>]).</p

PCA ordination of nine pollen taxa with percentages >5% in any sample of pollen assemblages from Lake Moon.

<p>PCA ordination of nine pollen taxa with percentages >5% in any sample of pollen assemblages from Lake Moon.</p

sj-docx-1-hol-10.1177_09596836231197769 – Supplemental material for Holocene summer temperature record based on branched tetraethers in Northeast China

Supplemental material, sj-docx-1-hol-10.1177_09596836231197769 for Holocene summer temperature record based on branched tetraethers in Northeast China by Zeyang Zhu, Jing Wu, Jiaxin Lu, Guoqiang Chu, Patrick Rioual, Luo Wang and Jiaqi Liu in The Holocene</p

Copy number loss of HRH4 in GCs.

<p>(A) Real-time PCR assay was carried out as described under <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031207#s2" target="_blank">Materials and Methods</a> section, and the results were obtained from indicated group of samples. Boxplots of relative copy number of HRH4 mRNA measured with Real-Time PCR analysis showing median; box: 25th–75th percentile; bars: largest and smallest values within 1.5 box lengths; little cross: outliers. mRNA expression level of HRH4 in groups with deleted (n = 23) or unaltered (n = 108) DNA copies. (B) Representative figure of FISH analysis using chromosome 18q specific alpha satellite DNA probe and chromosome 18q11 specific probe for HRH4 gene. I. Nucleus of ANT tissue with two signals for each of green and orange, showing no deletion of chromosome 18q or HRH4 gene. II. Nucleus of GC tissue with 0–2 signals for green and 0–2 signals for orange, indicating relative deletion in chromosome 18q or HRH4 gene.</p

Decreased H4R expression in GCs.

<p>(A) Representative blots of HRH4 expression in normal mucosa and gastric tumor tissues. α-tubulin was used as a stable endogenous control. (B) The histogram shows the anlysis of the results from the immunoblottings. The relative expression value of HRH4 protein (normalized by α-tubulin) in GCs is expressed as an average ratio±s.e. of tumor dose to matched adjacent normal tissue dose. *p<0.01 vs. Control, ANT. (C) Real-time PCR assay was carried out as described under <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031207#s2" target="_blank">Materials and Methods</a> section, boxplots of relative HRH4 mRNA(HRH4/GAPDH) measured with real-time PCR analysis showing median; box: 25th–75th percentile; bars: largest and smallest values within 1.5 box lengths; little cross: outliers. The results were obtained from 3 reactions in each sample. (D) Representative immunofluorescent microscope analysis of paired samples of GC tissue and adjacent normal tissue using anti human HRH4 monoclonal antibody (red). Nuclei were stain with DAPI (blue). Sample I: gastric cancer (GC); sample II: adjacent normal control (ANT). Arrows point to region of positive staining.</p