A record of Lateglacial/Holocene environmental change from a high‐elevation site in the Intermountain West, USA

Abstract

Records of past vegetation and fire history can be complicated by changes in the depositional environment of a sampling location. However, these changes can alternatively be used as a measure of climate variability. Our study site, ca. 18.0 cal. ka BP record from Little Brooklyn Lake, Wyoming, located near the crest of the Snowy Range, records three moisture states. Initially, the lake was likely a glacier-fed pond indicated by the presence of Pediastrum algae colonies. Around 13.0 cal. ka BP this pond transitioned to a meadow environment, suggested by the loss of Pediastrum algae colonies and slow sedimentation rates. Meadow conditions were maintained until ca. 5.0 cal. ka BP when Pediastrum algae colony abundance increased,indicating the formation of a shallow lake. From 18.0 to ca. 5.0 cal. ka BP, the pollen record is suggestive of alpine vegetation conditions with relatively high spruce and herbaceous taxa. Low charcoal influx also characterizes the period between 18.0 and 5.0 cal. ka BP. After 5.0 cal. ka BP, the coincidence of the formation of shallow lake and pollen data, indicating a shift to a spruce and fir forest, suggests an increase in effective moisture. Fire remained rare in this basin over the entire record, however, once the lake established sedimentation rates and charcoal influx increased.

Holocene fire occurrence and alluvial responses at the leading edge of pinyon–juniper migration in the Northern Great Basin, USA

“…(e.g., Minckley et al, 2012;Brunelle et al, 2013). More importantly perhaps, precessional changes likely produced gradual shifts in the annual phasing of regional temperatures.…”

“…Controls on fire-climate relationships, such as precession-driven changes in insolation and the seasonal timing of moisture delivery, have not been constant over the Holocene (e.g., Berger, 1978), and changes in the seasonality of precipitation and summer convective storms could broadly influence fire activity throughout the western U.S. (e.g., Minckley et al, 2012;Brunelle et al, 2013). More importantly perhaps, precessional changes likely produced gradual shifts in the annual phasing of regional temperatures.…”

Regionalization of fire regimes in the Central Rocky Mountains, USA

“…1). In this context, the CRM can be viewed as the transition zone between the Great Basin, the Great Plains, the NRM, and the SRM (Brunelle et al, 2013). The CRM is of particular interest because currently precipitation in the CRM and NRM is influenced from westerly storms originating from the northern Pacific Ocean in the winter, and both experience summers that are relatively warm and dry (Mock, 1996;Shinker, 2010;Wise, 2010).…”

“…Past fire regimes in the NRM have been researched more heavily than those of the SRM, with even fewer fire reconstructions along the transition zone between the two regions (Minckley et al, 2007(Minckley et al, , 2012Brunelle et al, 2013). Based on climatic association, it is not understood whether the CRM has a distinct fire regime, or whether its fire regime is more similar to the NRM or SRM.…”

Postglacial vegetation history of southeastern Wyoming, U.S.A.

“…Paleoecological records from southeastern Wyoming form a ~56 km-long transect spanning an elevation gradient of nearly 1300 m that includes upper tree line to arid-lowland basin environments (Knight, 1994). The available records for southeastern Wyoming allow for a synthesis of vegetation changes that have occurred in that region (J. M. Beiswenger, unpublished data; Brunelle et al, 2013;Carter et al, 2013;Mensing et al, 2012;Minckley et al, 2012). Three sites (West Glacier Lake, East Glacier Lake, and Little Brooklyn Lake) are near the crest of the Medicine Bow Mountains directly associated with the Snowy Range.…”