Publication Date:
2012-12-21
Description:
High-resolution pollen, plant macrofossil and magnetic susceptibility (MS) data are presented from an alpine lake sediment core from west-central Colorado, recording changes in vegetation and sedimentation for the latest Pleistocene and Holocene ( c . the last 12.5 ka; 1 ka = 1000 cal. yr BP). During the Younger Dryas chron ( c . 12.9–11.5 ka), Artemisia steppe or tundra grew around the lake, but by the earliest Holocene (10.7–9.5 ka) a subalpine Picea and Abies parkland was established there. Picea remained important through the early Holocene, but also bristlecone and lodgepole pines ( Pinus aristata and P. contorta ) grew around the lake. Warming conditions are indicated from 9.5 ka, lasting until c . 4.5–3.5 ka, which may have been the warmest period, with greatest development of monsoonal conditions. Trees subsequently retreated downslope from Kite Lake c . 150–200 m during the last 3.5 ka, establishing their present treeline position. A decrease in total Pinus and increases in Artemisia and piñon ( P. edulis ) indicate a trend toward progressive climate cooling and enhanced winter precipitation. These long-term climatic trends correlate with Holocene changes in summer insolation.
Print ISSN:
0959-6836
Electronic ISSN:
1477-0911
Topics:
Geography
,
Geosciences
Permalink
