Multiproxy record of late Pleistocene-Holocene climate and vegetation changes from a peat bog in Patagonia

Pollen assemblage changes and stable hydrogen isotope analysis of mosses (S phagnum magellanicum and Drepanocladus s.l.) from a bog in Tierra del Fuego , Argentina, provided independent proxies for reconstructing changes in eff ective moisture and temperature over the past 16,000 cal yr B.P. A determin istic model was used to reconstruct the stable hydrogen isotope composition of meteoric water from the D/H ratios of bog mosses over the last 16,000 y ears. Abrupt changes in temperature, as recorded in D/H ratios of moss cell ulose, were accompanied by synchronous changes in vegetation composition du ring the late Pleistocene and early and middle Holocene, when moisture leve ls were lower than today. In contrast, temperature variability during the l ate Holocene was not accompanied by comparable vegetation changes. In parti cular, grass pollen (Poaceae) increased during periodic cold spells between 15,000 and 11,000 cal yr B.P., but a cold spell of similar magnitude ca. 2 000 cal yr B.P did not appear to affect vegetation. During the late Pleisto cene, the isotopic record from the peat core shows variations similar to th e D/H ratios in the Antarctic Taylor Dome ice core. However, the timing of the changes in the Harberton record is more in line with the timing of othe r Southern Hemisphere records. (C) 2001 University of Washington.