Abstract

Pollen and plant macrofossils recovered from Little Lake, Oregon, provide the first record of late Quaternary climate and vegetation changes in Oregon's central Coast Range. The pollen data suggest that the period from ca. 42 000 to 24 770 yr B.P. featured an open forest of western white pine, western hemlock, and fir. The inferred climate was cooler and wetter than today. The full-glacial period was characterized by a parkland of spruce, lodgepole pine, and mountain hemlock, which suggests that the climate was colder and possibly drier than today. The Oregon Coast Range was not a glacial refugium for temperate conifers as has been proposed. By 16 000 yr B.P. the pollen and plant macrofossil data suggest the development of a montane forest composed of pine, fir, western hemlock, and mountain hemlock. Temperate taxa were present in the vegetation at 13 500 yr B.P. during a period of climatic amelioration. A reversal in this warming trend may have occurred between 11 000 and 10 500 yr B.P., when pine, western and mountain hemlock, and spruce were slightly more abundant. Early Holocene forests featured Douglas fir, red alder, and bracken fern, implying more severe summer drought and more frequent fires. After 5600 yr B.P., Douglas fir, western hemlock, and western red cedar dominated the record, marking the introduction of the present-day cool, moist climate; however, during the past 2800 yr, increased Douglas fir and decreased cedar suggest the possibility of reduced effective moisture at Little Lake.

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