Postglacial vegetation dynamics at high elevation from Fairy Lake in the northern Greater Yellowstone Ecosystem, Montana, USA

2019 ◽  
Vol 92 (2) ◽  
pp. 365-380 ◽  
Author(s):  
James V. Benes ◽  
Virginia Iglesias ◽  
Cathy Whitlock

AbstractThe postglacial vegetation and fire history of the Greater Yellowstone Ecosystem is known from low and middle elevations, but little is known about high elevations. Paleoecologic data from Fairy Lake in the Bridger Range, southwestern Montana, provide a new high-elevation record that spans the last 15,000 yr. The records suggest a period of tundra-steppe vegetation prior to ca. 13,700 cal yr BP was followed by open Picea forest at ca. 11,200 cal yr BP. Pinus-Pseudotsuga parkland was present after ca. 9200 cal yr BP, when conditions were warmer/drier than present. It was replaced by mixed-conifer parkland at ca. 5000 cal yr BP. Present-day subalpine forest established at ca. 2800 cal yr BP. Increased avalanche or mass-wasting activity during the early late-glacial period, the Younger Dryas chronozone, and Neoglaciation suggest cool, wet periods. Sites at different elevations in the region show (1) synchronous vegetation responses to late-glacial warming; (2) widespread xerothermic forests and frequent fires in the early-to-middle Holocene; and (3) a trend to forest closure during late-Holocene cooling. Conditions in the Bridger Range were, however, wetter than other areas during the early Holocene. Across the Northern Rockies, postglacial warming progressed from west to east, reflecting range-specific responses to insolation-driven changes in climate.

Author(s):  
Scott W. Dersam

Alpine landscapes capture our imaginations. Envisioning these forbidding regions occupied by humans in prehistory has drawn academic and public audiences alike. The history of these alpine regions is being rewritten the world over, due in part to recent archaeological discoveries made in the alpine regions of the Greater Yellowstone Ecosystem (GYE). These discoveries, some in the wilderness areas of Montana, have revealed a complex tapestry of prehistoric lifeways. Archaeological and paleobiological research in Montana’s GYE alpine regions by Dr. Craig Lee (INSTAAR/ PCRG), Dr. Rachel Reckin (USFS) and Scott Dersam (PCRG) have spearheaded these continued multi-disciplinary studies in the region. Their efforts have focused on the climatological, ecological, as well as cultural impacts of ice patch use and alpine habitation on patterns of prehistoric occupation in the region. The UW-NPS Research Station Small Grant funded archaeological research and reconnaissance of the alpine regions of Montana’s Beartooth wilderness during the summer 2019. The 2019-field season’s discoveries added significant knowledge to regional research in high elevation studies, documenting the highest known stone circles, ceramics, and Paleoindian hunting activities in Montana.   Featured photo from figure 4 in report. 


2019 ◽  
Vol 91 (2) ◽  
pp. 861-880 ◽  
Author(s):  
Teresa R. Krause ◽  
James M. Russell ◽  
Rui Zhang ◽  
John W. Williams ◽  
Stephen T. Jackson

AbstractThe patterns and drivers of late Quaternary vegetation dynamics in the southeastern United States are poorly understood due to low site density, problematic chronologies, and a paucity of independent paleoclimate proxy records. We present a well-dated (15 accelerator mass spectrometry14C dates) 30,000-yr record from White Pond, South Carolina that consists of high-resolution analyses of fossil pollen, macroscopic charcoal, andSporormiellaspores, and an independent paleotemperature reconstruction based on branched glycerol dialkyl tetraethers. Between 30,000 and 20,000 cal yr BP, openPinus-Piceaforest grew under cold and dry conditions; elevatedQuercusbefore 26,000 cal yr BP, however, suggest warmer conditions in the Southeast before the last glacial maximum, possibly corresponding to regionally warmer conditions associated with Heinrich event H2. Warming between 19,700 and 10,400 cal yr BP was accompanied by a transition from conifer-dominated to mesic hardwood forest.Sporormiellaspores were not detected and charcoal was low during the late glacial period, suggesting megaherbivore grazers and fire were not locally important agents of vegetation change.Pinusreturned to dominance during the Holocene, with step-like increases inPinusat 10,400 and 6400 cal yr BP, while charcoal abundance increased tenfold, likely due to increased biomass burning associated with warmer conditions. Low-intensity surface fires increased after 1200 cal yr BP, possibly related to the establishment of the Mississippian culture in the Southeast.


2012 ◽  
Vol 77 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Christy E. Briles ◽  
Cathy Whitlock ◽  
David J. Meltzer

The last glacial-interglacial transition (LGIT; 19–9 ka) was characterized by rapid climate changes and significant ecosystem reorganizations worldwide. In western Colorado, one of the coldest locations in the continental US today, mountain environments during the late-glacial period are poorly known. Yet, archaeological evidence from the Mountaineer site (2625 m elev.) indicates that Folsom-age Paleoindians were over-wintering in the Gunnison Basin during the Younger Dryas Chronozone (YDC; 12.9–11.7 ka). To determine the vegetation and fire history during the LGIT, and possible explanations for occupation during a period thought to be harsher than today, a 17-ka-old sediment core from Lily Pond (3208 m elev.) was analyzed for pollen and charcoal and compared with other high-resolution records from the southern Rocky Mountains. Widespread tundra and Picea parkland and low fire activity in the cold wet late-glacial period transitioned to open subalpine forest and increased fire activity in the Bølling–Allerød period as conditions became warmer and drier. During the YDC, greater winter snowpack than today and prolonged wet springs likely expanded subalpine forest to lower elevations than today, providing construction material and fuel for the early inhabitants. In the early to middle Holocene, arid conditions resulted in xerophytic vegetation and frequent fire.


Author(s):  
Robert B. Smith ◽  
Lee J. Siegel

In 1870, the fall before Ferdinand Hayden’s celebrated exploration of Yellowstone, an Army lieutenant named Gustavus C. Doane guided a small troop into the mysterious high country. Unlike Hayden, Doane did not conduct extensive scientific studies. However, Doane was observant. He said of Yellowstone: . . . As a country for sight seers, it is without parallel. As a field for scientific research it promises great results, in the branches of Geology, Mineralogy, Botany, Zoology, and Ornithology. It is probably the greatest laboratory that nature furnishes on the surface of the globe. . . . Yellowstone’s value as a unique ecological region soon gained recognition when in 1872, it was designated as the first national park in the United States—and in the world. The complex relationships among Yellowstone’s fauna, flora, and geology helped inspire America’s budding conservation ethic, which came to fruition only a century later with widespread recognition of the tenuous interdependence of living organisms and the Earth they occupy. The idea of a greater Yellowstone ecosystem recognized that its living and geological wonders extended beyond the park’s boundaries and into a broader area. The greater Yellowstone ecosystem is defined by the subterranean yet dominant presence of the Yellowstone hotspot, the engine that ultimately drives not only the region’s geology, but also its living organisms. The Rocky Mountains, lifted upward tens of millions of years ago, were pushed perhaps 1,700 feet higher at Yellowstone during the past 2 million years by the upward-bulging hotspot. Today, a line drawn at 6,100 feet elevation roughly demarcates the boundaries of the greater Yellowstone ecosystem. The high altitude is critical in creating the temperature and moisture regimes that gave rise to Yellowstone’s biological wonders and now determine the distribution of its plants and wildlife. In addition, the incredible amount of heat rising from the hotspot is responsible for Yellowstone’s history of volcanism and its geysers and hot springs, rich with exotic microbes that branched off the evolutionary tree at a primitive stage of life on Earth. Yelllowstone’s expansive lodgepole pine forests demonstrate the interaction of the park’s biology and geology. They grow well on rhyolite lava flows that cover most of western and central Yellowstone.


2015 ◽  
Vol 84 (3) ◽  
pp. 348-357 ◽  
Author(s):  
Alicia White ◽  
Christy Briles ◽  
Cathy Whitlock

The Cascade Range of southwestern Oregon contains some of North America's most diverse forests, but the ecological history of this area is poorly understood. A 7900-yr-long pollen and charcoal record was examined to better understand past changes in vegetation and fire activity in relation to large-scale climate variability. From 7900 to 3500 cal yr BP, the dominance of xerophytic species and the frequent fires are consistent with a climate that was warmer and drier than at present. The period from 3500 cal yr BP to present experienced an abundance of mesophytic taxa and reduced fire frequency, suggesting cooler and wetter conditions. The regional history of Abies indicates that it was most widespread during the late-glacial period; its range contracted during the early Holocene thermal maximum, and it steadily expanded during the middle and late Holocene. In contrast, Pseudotsuga was restricted in range during the glacial period, became abundant at low-elevation sites in the Coast and northern Cascade ranges during the early Holocene, and was more prevalent in southern mid-elevation sites as the climate became cooler and wetter in the late Holocene. The sensitivity of these species to past climate change suggests that biogeographic responses to future conditions will be highly variable in this region.


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