Climate and vegetation change during the late-glacial/early-Holocene transition inferred from multiple proxy records from Blacktail Pond, Yellowstone National Park, USA

A series of environmental changes from late-glacial ice recession through the early Holocene are revealed in a 7000-yr-long record of pollen, charcoal, geochemistry, and stable isotopes from Blacktail Pond, a closed-basin lake in Yellowstone National Park. Prior to 11,500. cal. yr. BP, cool conditions dominated, fire activity was low, and alpine tundra and Picea parkland grew on the landscape. A step-like climate change to warm summer conditions occurred at 11,500. cal. yr. BP. In response, fire activity increased facilitating a transition from Picea parkland to closed Pinus forest. From 11,500 to 8280. cal. yr. BP, warm summers and abundant moisture mostly likely from high winter snowfall supported closed Pinus contorta forests. Cooler drier summer conditions prevailed beginning 8280. cal. yr. BP due to decreased summer insolation and winter snowpack, and lower parkland developed. The timing of vegetation change in the Blacktail Pond record is similar to other low- and middle-elevation sites in the northern Rocky Mountains during the late-glacial period, suggesting local plant communities responded to regional-scale climate change; however, the timing of vegetation changes was spatially variable during the early and middle Holocene due to the varying influences of strengthened summer monsoons and subtropical high on regional precipitation patterns.