Postglacial Vegetation Dynamics at High Elevation from Fairy Lake in the Northern Greater Yellowstone Ecosystem, Montana, USA PDF Download
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Author: James V. Benes
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
The 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 vegitation 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 presernt. 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 aactivity 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) sunchronous 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 colling. 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: James V. Benes
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
The 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 vegitation 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 presernt. 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 aactivity 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) sunchronous 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 colling. 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: National Research Council
Publisher: National Academies Press
ISBN: 0309083451
Category : Science
Languages : en
Pages : 199
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Book Description
Ecological Dynamics on Yellowstone's Northern Range discusses the complex management challenges in Yellowstone National Park. Controversy over the National Park Service's approach of "natural regulation" has heightened in recent years because of changes in vegetation and other ecosystem components in Yellowstone's northern range. Natural regulation minimizes human impacts, including management intervention by the National Park Service, on the park ecosystem. Many have attributed these changes to increased size of elk and other ungulate herds. This report examines the evidence that increased ungulate populations are responsible for the changes in vegetation and that the changes represent a major and serious change in the Yellowstone ecosystem. According to the authors, any human intervention to protect species such as the aspen and those that depend on them should be prudently localized rather than ecosystem-wide. An ecosystem-wide approach, such as reducing ungulate populations, could be more disruptive. The report concludes that although dramatic ecological change does not appear to be imminent, approaches to dealing with potential human-caused changes in the ecosystem, including those related to climate change, should be considered now. The need for research and public education is also compelling.
Author: Teresa Rose Krause
Publisher:
ISBN:
Category : Paleobotany
Languages : en
Pages : 1104
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Book Description
The last glacial-interglacial transition in the western US (20,000-8000 years ago) was a period of rapid environmental change. In the Greater Yellowstone Ecosystem (GYE), much research has focused on postglacial vegetation changes; however, questions still remain regarding the relative trade-off between climate and nonclimatic factors, such as edaphic conditions, disturbance, and biotic interactions, in driving early postglacial vegetation development at finer spatial and temporal scales in the region. This study reconstructed vegetation development in the GYE from the time of ice retreat to the early Holocene insolation maximum (17,000-8000 years ago) at sub-regional and regional scales using fossil pollen data from three sites in the northern GYE and across a regional network of 13 previously published records. Fossil pollen data from lake sediments were compared to independent measures of climate (paleoclimate model simulations, stable isotope data), edaphic conditions (lithologic and geochemical data), and fire activity (charcoal data) to better understand climatic and nonclimatic drivers of early postglacial vegetation development. Climate was the primary driver of early postglacial vegetation development in the GYE. Increasing summer insolation and its direct effects on summer temperature and effective moisture directed changes in vegetation from pioneering herb and shrub communities to spruce parkland during the late-glacial period to subalpine forest and eventually open Douglas-fir forest by the early Holocene summer insolation maximum. Nonetheless, fire activity, site-specific edaphic conditions, and biotic interactions mediated vegetation responses to climate change. Elevated regional fire activity between 12,500 and 10,000 cal yr BP, driven by increasing summer temperatures and fuel biomass, facilitated important ecosystem changes from an Engelmann spruce and subalpine fir dominated system to one dominated by whitebark and lodgepole pine. Site-specific edaphic conditions, namely erosional processes associated with newly deglaciated terrain, inhibited early conifer expansion, and important competitive interactions between lodgepole pine and whitebark pine after the early Holocene limited the range of whitebark pine at middle elevations in the GYE. This research provides new insight into how ecosystems and plant species have responded to past climate change and is critical for better understanding local responses to regional climate change predicted in the coming decades.
Author: Teresa R. Krause
Publisher:
ISBN:
Category : Diatoms
Languages : en
Pages : 11
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A high-resolution record of pollen, charcoal, diatom, and lithologic data from Dailey Lake in southwestern Montana describes postglacial terrestrial and limnologic development from ice retreat ca. 16,000 cal yr BP through the early Holocene. Following deglaciation, the landscape surrounding Dailey Lake was sparsely vegetated, and erosional input into the lake was high. As summer insolation increased and ice recessional processes subsided, Picea parkland developed and diatoms established in the lake at 13,300 cal yr BP. Closed subalpine forests of Picea, Abies, and Pinus established at 12,300 cal yr BP followed by the development of open Pinus and Pseudotsuga forests at 10,200 cal yr BP. Increased planktic diatom abundance indicates a step-like warming at 13,100 cal yr BP, and alternations between planktic and tychoplankic taxa suggest changes in lake thermal structure between 12,400 and 11,400 cal yr BP. An increasingly open forest, in combination with increased benthic diatoms, indicates warm dry summers during the early Holocene after 11,400 cal yr BP, in contrast to nearby records in northern Yellowstone that register prolonged summer-wet conditions until ca. 8000 cal yr BP. Because of its low elevation, Dailey Lake was apparently sensitive to the direct effects of increased summer insolation on temperature and effective moisture, registering dry summers. In contrast, higher elevations in northern Yellowstone responded to the indirect effects of an amplified seasonal insolation cycle on atmospheric circulation, including elevated winter snowpack and/or increased summer convective storms as a result of enhanced monsoonal circulation.
Author: Robert B. Keiter
Publisher: Yale University Press
ISBN: 9780300059274
Category : Nature
Languages : en
Pages : 452
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Book Description
In 1872, Congress designated Yellowstone National Park as the world's first National Park. In this book, various experts in science, economics and law discuss key resource management issues in the greater Yellowstone ecosystem, and how humans should interact with the environment of this area.
Author: M. Allison Stegner
Publisher:
ISBN:
Category : Paleoecology
Languages : en
Pages : 11
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Book Description
Conifer forests of the western US are historically well adapted to wildfires, but current warming is creating novel disturbance regimes that may fundamentally change future forest dynamics. Stand-replacing fires can catalyze forest reorganization by providing periodic opportunities for establishment of new tree cohorts that set the stage for stand development for centuries to come. Extensive research on modern and past fires in the Northern Rockies reveals how variations in climate and fire have led to large changes in forest distribution and composition. Unclear, however, is the importance of individual fire episodes in catalyzing change. We used high-resolution paleoecologic and paleoclimatic data from Crevice Lake (Yellowstone National Park, Wyoming, USA), to explore the role of fire in driving low-elevation forest dynamics over the last 2820 yr. We addressed two questions: 1) did low-elevation forests at Crevice Lake experience abrupt community-level vegetation changes in response to past fire events? 2) Did the interaction of short-term disturbance events (fire) and long-term climate change catalyze past shifts in forest composition? Over the last 2820 yr, we found no evidence for abrupt community-level vegetation transitions at Crevice Lake, and no evidence that an interaction of climate and fire produced changes in the relative abundance of dominant plant taxa. In part, this result reflects limitations of the datasets to detect past event-specific responses and their causes. Nonetheless, the relative stability of the vegetation to fires over the last 2820 yr provides a local baseline for assessing current and future ecological change. Observations of climate?fire?vegetation dynamics in recent decades suggest that this multi-millennial-scale baseline may soon be exceeded.
Author:
Publisher:
ISBN:
Category : Botany
Languages : en
Pages : 372
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Author: Dennis Glick
Publisher:
ISBN:
Category : Biotic communities
Languages : en
Pages : 144
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Author: P. J. White
Publisher: Harvard University Press
ISBN: 0674076419
Category : Nature
Languages : en
Pages : 362
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Book Description
The world's first national park is constantly changing. How we understand and respond to recent events putting species under stress will determine the future of ecosystems millions of years in the making. Marshaling expertise from over 30 contributors, Yellowstone's Wildlife in Transition examines three primary challenges to the park's ecology.
Author: Alice Wondrak Biel
Publisher:
ISBN:
Category : Ecosystem management
Languages : en
Pages : 292
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