A general cooling trend on the central Tibetan Plateau throughout the Holocene recorded by the Lake Zigetang pollen spectra
A 741-cm-long laminated sediment core, covering the last 10,800 years was collected from Lake Zigetang, central Tibetan Plateau (90.9°E, 32.0°N, 4560 m a.s.l.), and analysed palynologically at 69 horizons. Biome reconstruction suggests a dominance of temperate steppe vegetation (mainly Artemisia and Poaceae) on the central Tibetan Plateau during the first half of the Holocene (10.8-4.4 cal. ka BP), while alpine steppes with desert elements (mainly Cyperaceae, Poaceae, Chenopodiaceae, and characteristic high-alpine herb families) tend to dominate the second half (4.4-0 cal. ka BP). The Artemisia/Cyperaceae ratio-a semi-quantitative measure for summer temperature-indicates a general cooling trend throughout the Holocene. Dense temperate steppe vegetation and maximum desert plant withdrawal, however, indicate that a suitable balance of wet and warm conditions for optimum vegetation growth likely occurred during the middle Holocene (7.3-4.4 cal. ka BP). Severe Early Holocene cold events have been reconstructed for 8.7-8.3 and ∼7.4 cal. ka BP. © 2006 Elsevier Ltd and INQUA.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL6-Earth climate variability since the Pliocene