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 The Role of Debris Cover in Catchment Runoff: A Case Study of the Hailuogou Catchment, South-Eastern Tibetan Plateau

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2601 ◽  
Author(s):  
Yong Zhang ◽  
Shiyin Liu ◽  
Qiao Liu ◽  
Xin Wang ◽  
Zongli Jiang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Elevation ◽  
The Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
South Eastern ◽  
Lower Elevation ◽  
Debris Cover ◽  
Physically Based ◽  
Catchment Runoff

Runoff from high-elevation, debris-covered glaciers is a crucial water supply in the Tibetan Plateau (TP) and its surroundings, where insufficient debris thickness data make it difficult to analyze its influence. Here, we investigated the role of debris cover in runoff formation of the Hailuogou catchment in the south-eastern Tibetan Plateau for the 1988–2017 period, based on long-term observations combined with a physically based glacio-hydrological model. The catchment is characterized by extensive thin debris on the ablation zones of three debris-covered glaciers. An increasing trend in catchment runoff has been observed in the past three decades, more than 50% of which is attributed to glacier runoff in the last decade. With the exception of the influence of temperature rising and precipitation decreasing, our results underline the importance of debris cover and its spatial features in the glaciological and hydrological processes of the catchment, in which the acceleration effect of debris cover is dominant in the catchment. An experimental analysis indicated that the extraordinary excess meltwater in the catchment is generated from the debris-covered surface, especially the lower elevation region below 3600 m a.s.l.

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 Lithospheric Structure of Eastern Tibetan Plateau from Terrestrial and Satellite Gravity Data Modeling: Implication for Asthenospheric Underplating

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-19
Author(s):  
Harshpal Singh ◽  
Rezene Mahatsente
Keyword(s):  
Tibetan Plateau ◽  
Gravity Models ◽  
Spatial Extent ◽  
Driving Mechanism ◽  
The Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
The West ◽  
Lithospheric Deformation ◽  
Lithospheric Thickness ◽  
The Past

Abstract The lithosphere of the eastern Tibetan plateau is underlain by a low-velocity zone at shallow depths which is interpreted as asthenospheric material in the upper-most mantle in various seismic tomography studies. The driving mechanism for the presence of asthenospheric material in the upper-most mantle is not well understood, and the spatial extent of the asthenospheric material is not well delineated. We use 2.5D gravity models to assess what drove the asthenospheric flow upwards in the past and determine the lateral extent of the asthenospheric material in the upper-most mantle. The models also allow us to determine the Indian slab configuration below the Tibetan plateau. The gravity models show that lithospheric thickness increases from ~120 km in the central and eastern parts of the plateau to ~150 km in the west, indicating that the lithosphere in the central and eastern parts of the plateau may have been delaminated. The ~30 km shallower Lithosphere-Asthenosphere Boundary in the central and eastern Tibetan plateau may indicate that asthenospheric flow could have been induced in the past by a combination of lithospheric delamination and a slab break-off event of the Greater Indian slab. The spatial extent of the asthenospheric material in the upper-most mantle beneath the Tibetan plateau is ~15,000 km2 (N−S length=500 km and thickness=30 km) between 85°E and 88°E, which could even extend east of 92°E. The Indian slab is dipping more steeply in the east. The slab dip along the Indian plate increases from ~10° in the west to ~18° in the central (~87°E) and ~25° in the eastern part (~91°E) of the plateau, indicating that the style of lithospheric deformation changes from underthrusting to slab roll-back from west to east.

Sign in / Sign up

Export Citation Format

Share Document