Holocene Vegetation and Climate Changes in the Hangay Mountains,

Central Mongolia

Laurel Stratton

Whitman College, Walla Walla WA 99362

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The Egiin Davaa region of the Hangay Mountains in central Mongolia is an area with a well-preserved record of Pleistocene glaciation. The modern climate does not allow glaciers but low temperatures support a periglacial environment with palsen fields, cryoplanation terraces, and permafrost within 1 m of the surface. Modern vegetation communities include scattered Siberian larch (Larix sibirica) forests with limited vertical range (≤ 150 m) on north-facing slopes, common small willows (Salix spp.), uncommon birch (Betula spp.), and one observed juniper (Juniperus sp.). Analysis of cores obtained from living Larix sibirica at elevations varying from 2197 to 2636 m date back several centuries and provide a record of temperature variation in the in the latest Holocene. Climate records extending back to the mid-Holocene are provided by pollen analysis conducted on peat collected at an elevation of 2278 m, just beyond the limit of late Pleistocene glaciation and ~100 m below the present-day lower Larix tree line. The 77-cm core with a basal 14C age of 4970 ± 20 is analyzed at approximately 500-year intervals against modern pollen ratios to construct a record of vegetation and climate changes since deposition of the basal peat. The results are compared to past research on climate change in Mongolia and to broader continental and global trends in climate, with particular emphasis on the late Hypsithermal, Neoglaciation, the Medieval Warm Period, the Little Ice Age, monsoonal changes, and the historical climate records.