Late Quaternary Vegetation and Climatic History of the Long Valley Area, West-Central Idaho, U.S.A.

Abstract

Paleoenvironmental data, including pollen and sediment analyses, radiocarbon ages, and tephra identifications of a core recovered from a fen, provide a ca. 16,500 14C yr B.P. record of late Quaternary vegetation and climate change in the Long Valley area of west-central Idaho. The fen was deglaciated prior to ca. 16,500 14C yr B.P., after which the pollen rain was dominated by Artemisia, suggesting that a cold, dry climate prevailed until ca. 12,200 14C yr B.P. From ca. 12,200 to 9750 14C yr B.P. temperatures gradually increased and a cool, moist climate similar to the present prevailed. During this period a closed spruce–pine forest surrounded the fen. This cool, moist climate was briefly interrupted by a dry and/or cold interval between ca. 10,800 and 10,400 14C yr B.P. that may be related to the Younger Dryas climatic oscillation. From ca. 9750 to 3200 14C yr B.P. the regional climate was significantly warmer and drier than at present and an open pine forest dominated the area around the fen. Maximum aridity occurred after the deposition of the Mazama tephra (ca. 6730 14C yr B.P.). After 3200 14C yr B.P. regional cooling brought cool, moist conditions to the area; the establishment of the modern montane forest around the fen and present-day cool and moist climate began at ca. 2000 14C yr B.P.

Fire and vegetation history during the last 3800 years in northwestern Montana

“…Previous paleoecological investigations in the NRM have identified periods of climate variability during the Late Holocene (Mehringer et al, 1977;Mack et al, 1983;Whitlock, 1992;Hallett and Walker, 2000;Doerner and Carrara, 2001;Brunelle-Daines, 2002;Brunelle and Whitlock, 2003). The detailed CHAR record from Foy Lake indicates three periods in the fire history.…”

“…The majority of paleoecological studies from the Northern Rocky Mountains (NRM) have focused on middle-and high-elevation sites where environmental changes in the Holocene have been primarily driven by climate variations and secondarily by human impacts (e.g., Mehringer et al, 1977;Whitlock, 1992;Reasoner and Huber, 1999;Doerner and Carrara, 2001;BrunelleDaines, 2002). In contrast, few sites have been studied at low elevations where prehistoric and Euro-American populations were larger and might have contributed significantly to landscape change (e.g., Mack et al, 1983;Hallett and Walker, 2000).…”

Post-glacial inflation-deflation cycles, tilting, and faulting in the Yellowstone Caldera based on Yellowstone Lake shorelines

“…HB Whitlock (1993), third from Mehringer and others (1984), and last from Doerner and Carrara, (2001). >11,510 ± 70 yr BP 13,460 (13,170-13,820) Turbid Lake explosion deposit 98P21B 8,410 ± 40 WW-2160 9,437_9,469 (9,300-9,525)…”

“…Several dated localities place the age of Glacier Peak ash at between ~13.4 and 14 ka (Table 1). In the Yellowstone-Grand Teton region, Whitlock (1993) Mehringer and others, 1984), studies in west central Idaho indicate an age older than 13.4 ka ( Table 1, 11,510 ± 70 yr BP; Doerner and Carrara, 2001). Based on the charcoal and ash ages and assuming that the lake sediment accumulated rapidly, we estimate an age of ~13 ka for the MB-II hydrothermal explosion deposits and ~12.6 ka for the S5 shoreline (Fig.…”

Late Quaternary Vegetation History of Northern North America Based on Pollen, Macrofossil, and Faunal Remains*

“…However, subalpine forest remained the dominant biome of the Cordilleran region (Mack et al, 1978(Mack et al, , 1979Thompson and Mead, 1982;Wells, 1983;Thompson et al, 1986;Rhode and Madsen, 1995). This was primarily a sprucepine forest in the Rocky Mountains (Vierling, 1998;Doerner and Carrara, 2001) and a spruce-pine-subalpine fir-mountain hemlock-alder forest in the wetter ranges west of the Great Basin (Barnosky, 1985;McLachlan and Brubaker, 1994;Sea and Whitlock, 1995). Within the Great Basin, bristlecone pine, limber pine, and junipers were the main trees.…”