کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4737612 1640902 2012 14 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Deglacial and postglacial vegetation changes on the eastern slopes of the central Patagonian Andes (47°S)
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Deglacial and postglacial vegetation changes on the eastern slopes of the central Patagonian Andes (47°S)
چکیده انگلیسی

We report pollen, spore, and charcoal records from Lago Augusta (47°05′S, 72°23′W, 440 m a.s.l.), a small closed-basin lake located near the modern forest-steppe ecotone east of the Andes in Central Patagonia, Chile. The record shows local ice-free conditions through the last glacial termination in the Río Chacabuco Valley and flooding by an ice-dammed lake. Once this proglacial lake ceased to inundate areas above 450 m a.s.l., the valley was colonized by herbs, shrubs and evergreen rainforest taxa between 15,600 and 16,000 cal yr BP, indicating an open landscape under cold/wet conditions. Millennial-scale fluctuations in the hygrophilous conifer Fitzroya/Pilgerodendron suggest precipitation variations within a cool/wet climate between 11,800 and 13,400 cal yr BP, followed by the establishment of dense Nothofagus forests between 9800 and 11,800 cal yr BP and declines in hygrophilous and cold-resistant trees, herbs and shrubs. This interval coincided with peak fire activity and laminated carbonate deposition. Nothofagus forests have persisted with little variation since 9800 cal yr BP, except for a sudden decline associated with a rapid increase in Rumex cf. acetosella, an exotic weed introduced by Europeans. Our results and interpretations are best explained by changes in the strength/position of the southern westerly winds at millennial and multi-millennial timescales since the last glaciation. Contrary to previous interpretations, we propose increased precipitation of westerly origin in the Andean sector of central-east Patagonia between 11,800 and 16,000 cal yr BP followed by a decline between 9800 and 11,800 cal yr BP and an increase thereafter. These trends are coherent with variations of the southern westerly winds identified in other terrestrial mid-latitude records, suggesting zonally symmetric changes in atmospheric circulation since the last glaciation.


► We present a 16,000-yr long vegetation and climate record from central Patagonia.
► The record suggests variations in Westerly wind strength at multi-millennial scale.
► Peak precipitation of westerly origin occurred during deglaciation (16–11.8 kyr BP).
► A precipitation minimum and peak fire activity took place between 11.8 and 9.8 kyr BP.
► Our results suggest zonally symmetric changes in westerly activity since last termination.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Quaternary Science Reviews - Volume 32, 16 January 2012, Pages 86–99
نویسندگان
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