A revised late-Quaternary vegetation history of the unglaciated southwestern Yukon Territory, Canada, from Antifreeze and Eikland ponds

Abstract

Antifreeze Pond was thought to contain the oldest record of continuous environmental change in the southwestern Yukon. We have revised the original interpretation of the vegetation history of Antifreeze Pond and this region based on new pollen, stomate, and macrofossil analysis, along with 38 new accelerator mass spectrometry (AMS) 14C dates from Antifreeze Pond and nearby Eikland Pond. Although the overall pattern of vegetation change is similar to the previously published Antifreeze Pond record, our new analysis indicates that the timing of the major vegetation shifts is substantially different, particularly during the late-glacial and early Holocene periods (from ∼17 000 – 9000 cal years BP). The original Antifreeze Pond record was thought to span a mid-Wisconsinan interstadial (>30 000 cal years BP) and the full-glacial period. Our results, however, indicate that the material of mid-Wisconsinan age was likely deposited by slumping around the pond making interpretation of the paleoenvironment difficult. Furthermore, our AMS 14C dates show that what was thought to be a full-glacial vegetation record is actually the vegetation history of the late-glacial period (ca. 17 000 – 11 000 cal years BP), which was a time of rapid sediment deposition into the ponds. The Eikland Pond record has an early Holocene Populus rise between ca. 11 000 – 8000 cal years BP that is not present in either the new or original Antifreeze Pond records. This new interpretation of the vegetation history should aid comparisons to other regional paleoenvironmental records.