Mosses of the Great Plains VI. The Niobrara River Basin of Nebraska

1982 ◽  
Vol 85 (1) ◽  
pp. 1 ◽  
Author(s):  
Steven P. Churchill
Keyword(s):  
River Basin ◽  
Great Plains ◽  
Niobrara River

scholarly journals Lacustrine evidence for moisture changes in the Nebraska Sand Hills during Marine Isotope Stage 3

2007 ◽  
Vol 67 (2) ◽  
pp. 246-254 ◽  
Author(s):  
Kimberly C. Jacobs ◽  
Sherilyn C. Fritz ◽  
James B. Swinehart
Keyword(s):  
Late Pleistocene ◽  
Great Plains ◽  
Lacustrine Sediments ◽  
Marine Isotope Stage ◽  
Nebraska Sand Hills ◽  
Lake Formation ◽  
Sand Hills ◽  
Niobrara River ◽  
Northern Edge ◽  
Marine Isotope Stage 3

AbstractIn the central Great Plains of North America, loess stratigraphy suggests that climate during the late Pleistocene was cold and dry. However, this record is discontinuous, and there are few other records of late-Pleistocene conditions. Cobb Basin, located on the northern edge of the Nebraska Sand Hills, contains lacustrine sediments deposited during Marine Isotope Stage 3, beginning approximately 45,000 cal yr BP and continuing for at least 10,000 yr. The lake was formed by a dune dam blockage on the ancient Niobrara River, and its deposits contain a diatom record that indicates changes through time in lake depth driven by changes in effective moisture. During the earliest stages of lake formation, the climate was arid enough to mobilize dunes and emplace dune sand into a blocking position within the Niobrara streambed. Diatom assemblages suggest that lake-level was shallow at formation, increased substantially during a wet interval, and then became shallow again, as arid conditions resumed. By about 27,000 cal yr BP the lake was filled, and a shallow ephemeral river occupied the basin.

Hydroclimatic Change in Southern Manitoba Since A.D. 1409 Inferred from Tree Rings

2002 ◽  
Vol 58 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Scott St. George ◽  
Erik Nielsen
Keyword(s):  
River Basin ◽  
Great Plains ◽  
Red River ◽  
Tree Ring Chronology ◽  
Quercus Macrocarpa ◽  
The North ◽  
Red River Basin ◽  
Bur Oak ◽  
Dry Conditions ◽  
Hydroclimatic Change

AbstractA record of estimated annual (prior August to current July) precipitation derived from a regional bur oak (Quercus macrocarpa Michx.) tree-ring chronology indicates that southern Manitoba's hydroclimate has been relatively stable over the last 200 yr. Although this stability was interrupted briefly by pronounced wet intervals in the late A.D. 1820s and 1850s, hydroclimatic conditions since permanent Euro-Canadian settlement were much less variable and persistent than those prior to A.D. 1790. The reconstruction indicates that the Red River basin experienced extremely dry conditions between A.D. 1670 and 1775, with below-normal precipitation occurring approximately 2 years out of 3. Annual precipitation was estimated at more than two standard deviations below the mean during A.D. 1477, 1485, 1556, 1595, 1612, 1644, 1661, 1743, 1900, and 1980. Comparisons with limnological records from North Dakota and Minnesota suggest that multidecadal fluctuations in regional hydroclimate have been remarkably coherent across the northeastern Great Plains during the last 600 yr. However, individual dry years in the Red River basin were usually associated with larger scale drought across much of the North American interior.

Postglacial Vegetation History of the Mackenzie River Basin

1987 ◽  
Vol 28 (2) ◽  
pp. 245-262 ◽  
Author(s):  
Glen M. MacDonald
Keyword(s):  
River Basin ◽  
Great Plains ◽  
Vegetation Change ◽  
Vegetation History ◽  
Mackenzie Delta ◽  
Last Deglaciation ◽  
Vegetation Development ◽  
Plant Migration ◽  
Mackenzie River Basin ◽  
Mackenzie River

AbstractThree radiocarbon-dated cores from small lakes provide pollen records of postglacial vegetation change in the central Mackenzie River basin. These data are combined with previously published records to reconstruct vegetation development from central Alberta to the Mackenzie delta. The paleoecological data demonstrate that a continuous corridor of herb-and-shrub-dominated vegetation extended between Beringia and the Great Plains of North America from deglaciaiton until about 10,000 yr B.P. The initial vegetation was replaced by spruce forests between 10,000 and 8500 yr B.P. Significant vegetation change continued until approximately 500 yr B.P. when the muskeg-dominated landscape typical of the present subarctic was established. The initial herb-and-shrub vegetation was likely a reprise of conditions which existed during earlier Pleistocene deglaciations. These conditions may have provided a favorable environment for animals adapted to nonforested vegetation and promoted migration southward from Beringia and northward from the Great Plains during the last deglaciation and earlier Pleistocene deglaciations. The sequence of postglacial vegetation change in the Mackenzie basin likely reflects a combination of climatic change, edaphic change, and plant migration patterns and interactions.

scholarly journals Transport of Atmospheric Moisture during Three Extreme Rainfall Events over the Mackenzie River Basin

2005 ◽  
Vol 6 (4) ◽  
pp. 423-440 ◽  
Author(s):  
Julian C. Brimelow ◽  
Gerhard W. Reuter
Keyword(s):  
Gulf Of Mexico ◽  
River Basin ◽  
Great Plains ◽  
Summer Rainfall ◽  
Northern Great Plains ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Low Level ◽  
Mackenzie River Basin ◽  
Mackenzie River

Abstract Lagrangian trajectories were computed for three extreme summer rainfall events (with rainfall exceeding 100 mm) over the southern Mackenzie River basin to test the hypothesis that the low-level moisture feeding these rainstorms can be traced back to the Gulf of Mexico. The three-dimensional trajectories were computed using the Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT). For all three events, parcel trajectories were identified that originated near the Gulf of Mexico and terminated over the southern Mackenzie River basin. Specifically, the transport of low-level moisture was found to occur along either quasi-continuous or stepwise trajectories. The time required to complete the journey varied between 6 and 10 days. Closer examination of the data suggests that, for the three cases in question, the transport of modified Gulf of Mexico moisture to high latitudes was realized when the northward extension of the Great Plains low-level jet to the Dakotas occurred in synch with rapid cyclogenesis over Alberta, Canada. In this way, modified low-level moisture from the Gulf of Mexico arrived over the northern Great Plains at the same time as a strong southerly flow developed over the Dakotas and Saskatchewan, Canada, in advance of the deepening cutoff low over Alberta. This moist air was then transported northward over Saskatchewan and finally westward over the southern Mackenzie River basin, where strong ascent occurred.

scholarly journals Wyoming’s Ucross Ranch: Its Birds, History, and Natural Environment

2019 ◽  
pp. 1-85
Author(s):  
Jacqueline Canterbury ◽  
Paul Johnsgard
Keyword(s):  
River Basin ◽  
Great Plains ◽  
Natural Environment ◽  
Habitat Type ◽  
Bird Species ◽  
Powder River Basin ◽  
Seasonal Abundance ◽  
Sagebrush Steppe ◽  
History Of ◽  
Environmental Adaptations

This book profiles 60 of the most abundant, characteristic, and interesting birds that have been regularly reported from the Ucross Ranch and the adjacent Powder River Basin. The 20,000-acre Ucross Ranch lies on the western edge of the Powder River Basin of northeastern Wyoming. Ucross is a textbook example of the prairie grassland/shrubland habitat type referred to as the sagebrush steppe, a landscape that is an icon of Wyoming’s vast open spaces. We focus especially on those species that occur year-round or are present as breeders during the summer months, and we place emphasis on a unique group of sagebrush steppe–adapted birds. We provide information on each profiled species’ identification, voice, status, and habitats. “Identification” describes its important visual characteristics (field marks), “voice” provides information on its songs and calls, “status” indicates its relative regional and seasonal abundance, and “habitats and ecology” provides a brief description of its behavior and environmental adaptations. Each species profile also has a calendar of average weekly seasonal occurrence based on long-term regional records. An introductory essay describes the early history of the Ucross Ranch, which is followed by essays on the natural environment and habitats of the ranch, including the characteristic sagebrush steppe and its associated bird species. The 22,000-word text is supplemented with 60 color bird photographs, a map of the vegetation communities in the Great Plains, and a Bird Checklist of the Ucross Ranch.

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