Late-glacial and Early Postglacial Vegetation and Climate Change in the Northeastern Great Plains PDF Download
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Author: Catherine Helen Yansa
Publisher:
ISBN:
Category :
Languages : en
Pages : 368
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Book Description
Author: Catherine Helen Yansa
Publisher:
ISBN:
Category :
Languages : en
Pages : 368
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Book Description
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: Dennis Ojima
Publisher: Island Press
ISBN: 161091435X
Category : Nature
Languages : en
Pages : 221
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Book Description
Great Plains : social-ecological setting (climate-environment-society) natural resources and wildlife aspects --Characteristics of agricultural system and energy resources --Climate conditions and scenarios of change across the Great Plains --Water management --Ecosystem and biodiversity conservation issues --Energy considerations --Agriculture and land management --Great Plains societal considerations : impacts and consequences, vulnerability and risk, adaptive capacity, response options --Collaborative research and management interactions in response to climate change.
Author: Teresa R. Krause
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 12
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Book Description
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.
Author: F. M. Chambers
Publisher: Springer
ISBN:
Category : Juvenile Nonfiction
Languages : en
Pages : 330
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Book Description
Part 1. Precision and Accuracy in Studies of Climatic Change and Human Impact -- 1: Precision, concepts, controversies: Alan Smith's contributions to vegetational history and palaeoecology -- 2: Forward to the past: changing approaches to Quaternary palaeoecology -- 3: Radiocarbon dating and the palynologist: a realistic approach to precision and accuracy -- 4: Great oaks from little acorns ... : precision and accuracy in Irish dendrochronology Part 2. Climatic Change on the Landscape -- 5: Peat bogs as sources of proxy climatic data: past approaches and future research -- 6: Forest response to Holocene climatic change: equilibrium or non-equilibnum -- 7: Isolating the climatic factors in early- and mid-Holocene palaeobotanical records from Scotland -- 8: Radiocarbon dating of arctic-alpine palaeosols and the reconstruction of Holocene palaeoenvironmental change. Part 3. Evidence for Human Impact -- 9: Earliest palynological records of human impact on the world's vegetation -- 10: Vegetation change during the Mesolithic in the British Isles: some amplifications -- 11: The development of high moorland on Dartmoor: fire and the influence of Mesolithic activity on vegetation change -- 12: Models of mid-Holocene forest farming for north-west Europe -- 13: The influence of human communities on the English chalklands from the Mesolithic to the Iron Age: the molluscan evidence -- 14: Mesolithic, early Neolithic, and later prehistoric impacts on vegetation at a riverine site in Derbyshire, England -- 15: Holocene (Flandrian) vegetation change and human activity in the Carneddau area of upland mid-Wales -- 16: Early land use and vegetation history at Derryinver Hill, Renvyle Peninsula, Co. Calway, Ireland. Part 4. Climatic Change and Human Impact: Relationship and Interaction --17: Rapid early-Holocene migration and high abundance of hazel (Corylus avellana L.): alternative hypotheses -- 18: The origin of blanket mire, revisited -- 19: Climatic change and human impact during the late Holocene in northern Britain -- 20: Palaeoecology of floating bogs and landscape change in the Great Lakes drainage basin of North America -- 21: Late Quaternary climatic change and human impact: commentary and conclusions.
Author: Yongbo Wang
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The past climate in central Asia, and especially on the Tibetan Plateau (TP), is of great importance for an understanding of global climate processes and for predicting the future climate. As a major influence on the climate in this region, the Asian Summer Monsoon (ASM) and its evolutionary history are of vital importance for accurate predictions. However, neither the evolutionary pattern of the summer monsoon nor the driving mechanisms behind it are yet clearly understood. For this research, I first synthesized previously published Late Glacial to Holocene climatic records from monsoonal central Asia in order to extract the general climate signals and the associated summer monsoon intensities. New climate and vegetation sequences were then established using improved quantitative methods, focusing on fossil pollen records recovered from Tibetan lakes and also incorporating new modern datasets. The pollen-vegetation and vegetation-climate relationships on the TP were also evaluated in order to achieve a better understanding of fossil pollen records. The synthesis of previously published moisture-related palaeoclimate records in monsoonal central Asia revealed generally different temporal patterns for the two monsoonal subsystems, i.e. the Indian Summer Monsoon (ISM) and East Asian Summer Monsoon (EASM). The ISM appears to have experienced maximum wet conditions during the early Holocene, while many records from the area affected by the EASM indicate relatively dry conditions at that time, particularly in north-central China where the maximum moisture levels occurred during the middle Holocene. A detailed consideration of possible driving factors affecting the summer monsoon, including summer solar insolation and sea surface temperatures, revealed that the ISM was primarily driven by variations in northern hemisphere solar insolation, and that the EASM may have been constrained by the ISM resulting in asynchronous patterns of evolution for these two subsystems. This hypothesis is further supported by modern monsoon indices estimated using the NCEP/NCAR Reanalysis data from the last 50 years, which indicate a significant negative correlation between the two summer monsoon subsystems. By analogy with the early Holocene, intensification of the ISM during coming decades could lead to increased aridification elsewhere as a result of the asynchronous nature of the monsoon subsystems, as can already be observed in the meteorological data from the last 15 years. A quantitative climate reconstruction using fossil pollen records was achieved through analysis of sediment core recovered from Lake Donggi Cona (in the north-eastern part of the TP) which has been dated back to the Last Glacial Maximum (LGM). A new data-set of modern pollen collected from large lakes in arid to semi-arid regions of central Asia is also presented herein. The concept of "pollen source area" was introduced to modern climate calibration based on pollen from large lakes, and was applied to the fossil pollen sequence from Lake Donggi Cona. Extremely dry conditions were found to have dominated the LGM, and a subsequent gradually increasing trend in moisture during the Late Glacial period was terminated by an abrupt reversion to a dry phase that lasted for about 1000 years and coincided with the first Heinrich Event of the northern Atlantic region. Subsequent periods corresponding to the warm Bølling-Allerød period and the Younger Dryas cold event were followed by moist conditions during the early Holocene, with annual precipitation of up to about 400 mm. A slightly drier trend after 9 cal ka BP was then followed by a second wet phase during the middle Holocene that lasted until 4.5 cal ka BP. Relatively steady conditions with only slight fluctuations then dominated the late Holocene, resulting in the present climatic conditions. In order to investigate the relationship between vegetation and climate, temporal variations in the possible driving factors for vegetation change on the northern TP were examined using a high resolution late Holocene pollen record from Lake Kusai. Moving-window Redundancy Analyses (RDAs) were used to evaluate the correlations between pollen assemblages and individual sedimentary proxies. These analyses have revealed frequent fluctuations in the relative abundances of alpine steppe and alpine desert components, and in particular a decrease in the total vegetation cover at around 1500 cal a BP. The climate was found to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, after the 1500 cal a BP threshold in vegetation cover was crossed the vegetation appears to have been affected more by extreme events such as dust storms or fluvial erosion than by the general climatic trends. In addition, pollen spectra over the last 600 years have been revealed by Procrustes analysis to be significantly different from those recovered from older samples, which is attributed to an increased human impact that resulted in unprecedented changes to the composition of the vegetation. Theoretical models that have been developed and widely applied to the European area (i.e. the Extended R-Value (ERV) model and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model) have been applied to the high alpine TP ecosystems in order to investigate the pollen-vegetation relationships, as well as for quantitative reconstructions of vegetation abundance. The modern pollen-vegetation relationships for four common pollen species on the TP have been investigated using Poaceae as the reference taxa. The ERV Submodel 2 yielded relatively high PPEs for the steppe and desert taxa (Artemisia Chenopodiaceae), and low PPEs for the Cyperaceae that are characteristic of the alpine Kobresia meadows. The plant abundances on the central and north-eastern TP were quantified by applying these PPEs to four post-Late Glacial fossil pollen sequences. The reconstructed vegetation assemblages for the four pollen sequences always yielded smaller compositional species turnovers than suggested by the pollen spectra, indicating that the strength of the previously-reported vegetation changes may therefore have been overestimated. In summary, the key findings of this thesis are that (a) the two ASM subsystems show asynchronous patterns during both the Holocene and modern time periods, (b) fossil pollen records from large lakes reflect regional signals for which the pollen source areas need to be taken into account, (c) climate is not always the main driver for vegetation change, and (d) previously reported vegetation changes on the TP may have been overestimated because they ignored inter-species variations in pollen productivity
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 712
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Author: Geoff Cunfer
Publisher: Texas A&M University Press
ISBN: 1623494753
Category : History
Languages : en
Pages : 341
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Book Description
The near disappearance of the American bison in the nineteenth century is commonly understood to be the result of over-hunting, capitalist greed, and all but genocidal military policy. This interpretation remains seductive because of its simplicity; there are villains and victims in this familiar cautionary tale of the American frontier. But as this volume of groundbreaking scholarship shows, the story of the bison’s demise is actually quite nuanced. Bison and People on the North American Great Plains brings together voices from several disciplines to offer new insights on the relationship between humans and animals that approached extinction. The essays here transcend the border between the United States and Canada to provide a continental context. Contributors include historians, archaeologists, anthropologists, paleontologists, and Native American perspectives. This book explores the deep past and examines the latest knowledge on bison anatomy and physiology, how bison responded to climate change (especially drought), and early bison hunters and pre-contact trade. It also focuses on the era of European contact, in particular the arrival of the horse, and some of the first known instances of over-hunting. By the nineteenth century bison reached a “tipping point” as a result of new tanning practices, an early attempt at protective legislation, and ventures to introducing cattle as a replacement stock. The book concludes with a Lakota perspective featuring new ethnohistorical research. Bison and People on the North American Great Plains is a major contribution to environmental history, western history, and the growing field of transnational history.
Author: Warren W. Caldwell
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages : 164
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Author: The BACC II Author Team
Publisher: Springer
ISBN: 3319160060
Category : Science
Languages : en
Pages : 515
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Book Description
This book is an update of the first BACC assessment, published in 2008. It offers new and updated scientific findings in regional climate research for the Baltic Sea basin. These include climate changes since the last glaciation (approx. 12,000 years ago), changes in the recent past (the last 200 years), climate projections up until 2100 using state-of-the-art regional climate models and an assessment of climate-change impacts on terrestrial, freshwater and marine ecosystems. There are dedicated new chapters on sea-level rise, coastal erosion and impacts on urban areas. A new set of chapters deals with possible causes of regional climate change along with the global effects of increased greenhouse gas concentrations, namely atmospheric aerosols and land-cover change. The evidence collected and presented in this book shows that the regional climate has already started to change and this is expected to continue. Projections of potential future climates show that the region will probably become considerably warmer and wetter in some parts, but dryer in others. Terrestrial and aquatic ecosystems have already shown adjustments to increased temperatures and are expected to undergo further changes in the near future. The BACC II Author Team consists of 141 scientists from 12 countries, covering various disciplines related to climate research and related impacts. BACC II is a project of the Baltic Earth research network and contributes to the World Climate Research Programme.
