scholarly journals Fire, vegetation, and Holocene climate in a southeastern Tibetan lake: a multi-biomarker reconstruction from Paru Co

2018 ◽  
Vol 14 (10) ◽  
pp. 1543-1563 ◽  
Author(s):  
Alice Callegaro ◽  
Dario Battistel ◽  
Natalie M. Kehrwald ◽  
Felipe Matsubara Pereira ◽  
Torben Kirchgeorg ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Holocene ◽  
Fire History ◽  
Forest Cover ◽  
Ice Core ◽  
Vegetation Changes ◽  
The Tibetan Plateau ◽  
Core Sediment ◽  
The Holocene ◽  
Surrounding Areas

Abstract. The fire history of the Tibetan Plateau over centennial to millennial timescales is not well known. Recent ice core studies reconstruct fire history over the past few decades but do not extend through the Holocene. Lacustrine sedimentary cores, however, can provide continuous records of local environmental change on millennial scales during the Holocene through the accumulation and preservation of specific organic molecular biomarkers. To reconstruct Holocene fire events and vegetation changes occurring on the southeastern Tibetan Plateau and the surrounding areas, we used a multi-proxy approach, investigating multiple biomarkers preserved in core sediment samples retrieved from Paru Co, a small lake located in the Nyainqentanglha Mountains (29∘47′45.6′′ N, 92∘21′07.2′′ E; 4845 m a.s.l.). Biomarkers include n-alkanes as indicators of vegetation, polycyclic aromatic hydrocarbons (PAHs) as combustion proxies, fecal sterols and stanols (FeSts) as indicators of the presence of humans or grazing animals, and finally monosaccharide anhydrides (MAs) as specific markers of vegetation burning processes. Insolation changes and the associated influence on the Indian summer monsoon (ISM) affect the vegetation distribution and fire types recorded in Paru Co throughout the Holocene. The early Holocene (10.7–7.5 cal kyr BP) n-alkane ratios demonstrate oscillations between grass and conifer communities, resulting in respective smouldering fires represented by levoglucosan peaks, and high-temperature fires represented by high-molecular-weight PAHs. Forest cover increases with a strengthened ISM, where coincident high levoglucosan to mannosan (L ∕ M) ratios are consistent with conifer burning. The decrease in the ISM at 4.2 cal kyr BP corresponds with the expansion of regional civilizations, although the lack of human FeSts above the method detection limits excludes local anthropogenic influence on fire and vegetation changes. The late Holocene is characterized by a relatively shallow lake surrounded by grassland, where all biomarkers other than PAHs display only minor variations. The sum of PAHs steadily increases throughout the late Holocene, suggesting a net increase in local to regional combustion that is separate from vegetation and climate change.

scholarly journals Fire, vegetation and Holocene climate in the south-eastern Tibetan Plateau: a multi-biomarker reconstruction from Paru Co

2018 ◽  
Author(s):  
Alice Callegaro ◽  
Felipe Matsubara Pereira ◽  
Dario Battistel ◽  
Natalie M. Kehrwald ◽  
Broxton W. Bird ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Biomass Burning ◽  
Fire History ◽  
Vegetation Changes ◽  
The Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
The South ◽  
South Eastern ◽  
The Past ◽  
High Concentrations

Abstract. The fire history of the Tibetan Plateau over centennial to millennial timescales is still unknown. Recent ice core studies reconstruct fire history over the past few decades but do not extend through the Holocene. Lacustrine sedimentary cores, however, provide continuous records of large-scale and local environmental modifications due to their accumulation of specific organic molecular markers throughout the past millennia. In order to reconstruct Holocene fire events and vegetation changes occurring on the south-eastern Tibetan Plateau and the surrounding areas, we improved and integrated previous analytical methods. The multi-proxy procedure was applied to samples retrieved from Paru Co, a small lake located in the Nyainqentanglha Mountains (29°47'45.6" N; 92°21'07.2" E; 4845 m a.s.l.). The investigated biomarkers include n-alkanes as indicators of vegetation, polycyclic aromatic hydrocarbons (PAHs) as combustion proxies, faecal sterols and stanols (FeSts) as indicators of the presence of humans or grazing animals and finally monosaccharide anhydrides (MAs) as specific markers of vegetation burning processes. Relatively high concentrations of both MAs and PAHs demonstrate intense local biomass burning activity during the early Holocene (10.9–10.7 cal ky BP), which correspond to a drier climate following deglaciation. High concentrations of MAs but not PAHs between 10.7–9 cal ky BP suggest a period of regional biomass burning followed by a decreasing fire trend through the mid-late Holocene. This fire history is consistent with local vegetation changes reconstructed from both n-alkanes and regional pollen records, where vegetation types depend on the centennial-scale intensity of monsoon precipitation. FeSts were below detection limits for most of the samples, suggesting limited direct human influences on fire regime and vegetation changes in the lake's catchment. Climate is the main influence on fire activity recorded in Paru Co over millennial timescales, where biomass burning fluctuates in response to alternating warm/humid and cool/dry periods.

scholarly journals Brief communication: New evidence further constraining Tibetan ice core chronologies to the Holocene

2021 ◽  
Vol 15 (4) ◽  
pp. 2109-2114
Author(s):  
Shugui Hou ◽  
Wangbin Zhang ◽  
Ling Fang ◽  
Theo M. Jenk ◽  
Shuangye Wu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ice Core ◽  
Ice Cores ◽  
Qilian Mountains ◽  
Time Range ◽  
The Holocene ◽  
Guliya Ice Core ◽  
Considerable Controversy ◽  
New Evidence

Abstract. There is considerable controversy regarding the age ranges of Tibetan ice cores. The Guliya ice core was reported to reach as far back as ∼760 ka (kiloannum, i.e. 1000 years), whereas chronologies of all other Tibetan cores cover at most the Holocene. Here we present ages for two new ice cores reaching bedrock, from the Zangser Kangri (ZK) glacier in the northwestern Tibetan Plateau and the Shulenanshan (SLNS) glacier in the western Qilian Mountains. We estimated bottom ages of 8.90±0.570.56 ka and 7.46±1.461.79 ka for the ZK and SLNS ice core respectively, further constraining the time range accessible by Tibetan ice cores to the Holocene.

scholarly journals Continuous Wetting on the Tibetan Plateau during 1970–2017

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2605 ◽  
Author(s):  
Huamin Zhang ◽  
Mingjun Ding ◽  
Lanhui Li ◽  
Linshan Liu
Keyword(s):  
Tibetan Plateau ◽  
Piecewise Linear ◽  
Growing Season ◽  
Significant Trend ◽  
The Tibetan Plateau ◽  
Intensity Analysis ◽  
Standardized Precipitation Evapotranspiration Index ◽  
Piecewise Linear Regression ◽  
Increasing Trend ◽  
Surrounding Areas

Based on daily observation records at 277 meteorological stations on the Tibetan Plateau (TP) and its surrounding areas during 1970–2017, drought evolution was investigated using the Standardized Precipitation Evapotranspiration Index (SPEI). First, the spatiotemporal changes in the growing season of SPEI (SPEIgs) were re-examined using the Mann–Kendall and Sen’s slope approach—the piecewise linear regression and intensity analysis approach. Then, the persistence of the SPEIgs trend was predicted by the Hurst exponent. The results showed that the SPEIgs on the TP exhibited a significant increasing trend at the rate of 0.10 decade−1 (p < 0.05) and that there is no significant trend shift in SPEIgs (p = 0.37), indicating that the TP tended to undergo continuous wetting during 1970–2017. In contrast, the areas surrounding the TP underwent a significant trend shift from an increase to a decrease in SPEIgs around 1984 (p < 0.05), resulting in a weak decreasing trend overall. Spatially, most of the stations on the TP were characterized by an increasing trend in SPEIgs, except those on the Eastern fringe of TP. The rate of drought/wet changes was relatively fast during the 1970s and 1980s, and gradually slowed afterward on the TP. Finally, the consistent increasing trend and decreasing trend of SPEIgs on the TP and the area East of the TP were predicted to continue in the future, respectively. Our results highlight that the TP experienced a significant continuous wetting trend in the growing season during 1970–2017, and this trend is likely to continue.

A comparative study of radiocarbon dating on terrestrial organisms and fish from Qinghai Lake in the northeastern Tibetan Plateau, China

The Holocene ◽  
2018 ◽  
Vol 28 (11) ◽  
pp. 1712-1719 ◽  
Author(s):  
E ChongYi ◽  
YongJuan Sun ◽  
XiangJun Liu ◽  
Guangliang Hou ◽  
ShunChang Lv ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Holocene ◽  
Sediment Cores ◽  
Qinghai Lake ◽  
The Tibetan Plateau ◽  
Fish Bones ◽  
Northeastern Tibetan Plateau ◽  
Animal Bones ◽  
Gymnocypris Przewalskii ◽  
The Difference

Qinghai Lake is the largest lake on the Tibetan Plateau (TP) and in China and has been a focus of paleoenvironmental and climatic research for decades. However, limited understanding of lake 14C reservoir effects (LRE) has led to inconsistent interpretations among proxies of different sediment cores. As such, the onset of LRE variability during the Holocene is still unclear. 14C dating of archeological samples from four locations (Gangcha, Shaliuheqiaoxi, and Shinaihai sites, and Niaodao section) including naked carp ( Gymnocypris przewalskii, Kessler) fish bones, animal bones and teeth, and charcoal was employed to estimate variations in LRE over the last few thousand years. LRE offsets calculated as the difference between LRE of animal bones and fish bones are more reliable than that of charcoal and fish bones due to the ‘old wood’ effect in charcoal. LRE offsets recorded in fish bones were ~0.5, ~0.6, and ~0.7 ka during the periods of 3.0–3.4 cal ka BP, 0.58–0.60 cal ka BP, and modern lake times, respectively, which may indicate a temporal minimum LRE offset. Unlike the wide spatial variations of LRE ages obtained from surface total organic carbon (TOC) samples of the modern Qinghai Lake, LRE offsets from the three contemporaneous locations in Qinghai Lake were all ~0.5 ka, suggesting efficient carbon mixing occurred in naked carp. However, the late-Holocene (~3.1 ka BP) LRE increased slightly with increasing salinity and decreasing lake level.

scholarly journals Seasonal Features and a Case Study of Tropopause Folds over the Tibetan Plateau

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Jiali Luo ◽  
Wenjun Liang ◽  
Pingping Xu ◽  
Haiyang Xue ◽  
Min Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Frequency ◽  
Reanalysis Data ◽  
The Tibetan Plateau ◽  
Transport Pathway ◽  
Westerly Jet ◽  
Meridional Winds ◽  
Surrounding Areas ◽  
High Potential Vorticity

Tropopause fold is the primary mechanism for stratosphere-troposphere exchange (STE) at the midlatitudes. Investigation of the features of tropopause folds over the Tibetan Plateau (TP) is important since the TP is a hotspot in global STE. In this study, we investigated seasonal features of the tropopause fold events over the TP using the 40-year ERA-Interim reanalysis data. The development of a tropopause folding case is specifically examined. The results show that shallow tropopause folds occur mostly in spring, while medium and deep folds occur mostly in winter. The multiyear mean monthly frequency of shallow tropopause folds over the TP reaches its maximum value of about 7% in May and then decreases gradually to its minimum value of 1% in August and increases again since September. Deep folds rarely occur in summer and autumn. Both the seasonal cycle and seasonal distribution of total tropopause folds over the TP are dominated by shallow folds. The relative high-frequency areas of medium and deep folds are located over the southern edge of the TP. The westerly jet movement controls the displacement of the high-frequency folding region over the TP. The region of high-frequency tropopause folds is located in the southern portion of the plateau in spring and moves northward in summer. The jet migrates back to the south in autumn and is located along about 30°N in winter, and the region where folds occur most frequently also shifts southward correspondingly. A medium fold event that occurred on 29 December 2018 is used to demonstrate the evolution of a tropopause fold case over the TP in winter; that is, the folding structure moves from west to east, the tropopause pressure is greater than 320 hPa over the folding region, while it is about 200 hPa in the surrounding areas, and the stratospheric air with high potential vorticity (PV) is transported from the high latitudes to the plateau by meridional winds. A trajectory model result verifies the transport pathway of the air parcels during the intrusion event.

Late Quaternary Glacial and Vegetation Changes, Little Cottonwood Canyon Area, Wasatch Mountains, Utah

1979 ◽  
Vol 12 (2) ◽  
pp. 254-270 ◽  
Author(s):  
David B. Madsen ◽  
Donald R. Currey
Keyword(s):  
Rocky Mountains ◽  
Late Holocene ◽  
Late Quaternary ◽  
Summer Temperature ◽  
Vegetation Changes ◽  
Glacial Geology ◽  
The Holocene ◽  
Wasatch Mountains ◽  
Relative Moisture

Glacial geology and 14C dating in the central Wasatch Mountains indicate: an early canyon-mouth glaciation (Dry Creek till), probably during isotope stage 6; on that till, a paleosol (Majestic Canyon soil) dated at about 26,000 yr B.P.; overriding that soil, a later canyon-mouth glaciation (Bells Canyon till) probably beginning prior to about 19,000 yr B.P.; a midcanyon deglacial pause (Hogum Fork till) prior to 12,300 yr B.P.; an upper-canyon deglacial pause (Devils Castle till) prior to 7500 yr B.P.; and late Holocene periglaciation. Pollen ratios from bog profiles in the mid to upper reaches of the canyon suggest that temperatures cooler than the Holocene average occurred until after about 8000 yr B.P. Warmer and dryer than average conditions were initiated about 8000 to 7500 yr B.P. During the later portion of this Altithermal period conditions became relatively warm and wet. Two subsequent episodes of cooler than average temperatures correspond chronologically to the initial stades of Neoglaciation elsewhere in the Rocky Mountains. However, there is no geomorphic evidence of corresponding glacial activity in the canyon area. Relative moisture during these two periods differs significantly, suggesting that Neoglacial conditions were controlled primarily by changes in summer temperature.

Sign in / Sign up

Export Citation Format

Share Document