Abstract
A sediment core recovered from Lost Park (39°17′30″N, 105°32′30″W; elevation 3079 m) provides palynological evidence for postglacial vegetational and environmental change in the central Front Range of Colorado. Pine–spruce woodland was the dominant vegetation type throughout the ∼12,000-yr-long record. Nonarboreal taxa, however, showed substantial changes. From 11,800 to 910014C yr B.P., highArtemisialevels suggest steppe vegetation indicative of a climate cooler than that at present with an annual precipitation regime dominated by winter moisture. The pollen spectra of this interval resemble modern spectra at two sites within Colorado and Wyoming; comparisons of modern climatic data suggest that Lost Park may have experienced winter temperatures 3° to 3.5°C colder than those at present and monthly winter precipitation levels 3.5 cm higher than those at present during this late-glacial time. LowerArtemisia,coupled with increases in Poaceae pollen, suggest a shift to warmer conditions dominated by summer (monsoon) precipitation around 910014C yr B.P. Increased charcoal occurrences between ∼6000 and ∼400014C yr B.P. may suggest the onset of drier summer conditions that would be expected with a waning summer monsoon circulation at that time. Since 180014C yr B.P., a resurgence inArtemisiapollen suggests a return to relatively cool and/or dry conditions similar to the present climate.
Published Version
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