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

Climate of the Past
By: , and 

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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; 4845ma.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 (10.7–7.5calkyrBP) 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 (LM) ratios are consistent with conifer burning. The decrease in the ISM at 4.2calkyrBP 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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Fire, vegetation, and Holocene climate in a southeastern Tibetan lake: a multi-biomarker reconstruction from Paru Co
Series title Climate of the Past
DOI 10.5194/cp-14-1543-2018
Volume 14
Year Published 2018
Language English
Publisher European Geophysical Union (EGU)
Contributing office(s) Geosciences and Environmental Change Science Center
Description 21 p.
First page 1543
Last page 1563
Country China