The Nebraska Sandhills
Excerpts taken from "An Atlas of The Sand Hills"
Ann Bleed and Charles Flowerday, Editors
Resource Atlas No. 5a, Conservation and Survey Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln. 1990
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The Sandhills region, is approximately 19,300 square miles of sand dunes stretching 265 miles across Nebraska. It is the largest sand dune area in the Western Hemispere and is one of the largest grass-stabilized dune regions in the world.
Topography, among other things, distinguishes the region from the surrounding prairies. Dunes are as high as 400 feet, as long as 20 miles, and have slopes as steep as 25 percent. Another distinguishing feature is that the large sand masses now held in place by grasses were formed by blowing sand during a surprisingly recent time, mostly during the last 8,000 years or less.
Precipitation in the Sandhills ranges from an average annual total of 23 inches in the east to slightly less than 17 inches in the extreme west. This decline from the east to west is the result of a combination of factors: 1)Nebraska's interior location; 2)the blocking effect of the Rocky Mountains on moisture from the Pacific Ocean; and 3)increasing distance from the Gulf of Mexico, the region's primary source of moisture.
The Sandhills are generally viewed as a semiarid region where sandy soils, low precipitation, and high evaporation rates support primarily dry grassland. Yet paradoxically, the Sandhills also are known as a land of lakes and wetlands. While many of the interdunal valleys are dry, many others contain lakes, marshes, and/or wet meadows. The Sandhills lie over a groundwater reservoir that holds about half of all the groundwater found in Nebraska, an estimated 700-800 million acre-feet of water.
As far as is known, there are about 720 species of vascular plants growing without cultivation in the Sandhills. About 670 of them are native species, and about 50 are introduced from elsewhere, especially from Europe and Asia. The number of species in the Sandhills appears low when compared with other grassland areas. However, perhaps because of moderate rainfall and plentiful groundwater, it is high compared with other areas of similarly sandy, relatively infertile soils.
The vegetation in the Sandhills is unique, not because it consists of many unusual species, but because it is a mixture of so many different types of vegetation. Although some authors have regarded the Sandhills as a western extension of the tallgrass prairie, this interpretation is not supported by observation. Rather than referring to the region's prairie as an extension of one type of prairie, it is better simply to recognize the unique association of plants and call the region's vegetation a Sandhills prairie.
In a sense, the vegetation of the Sandhills is "borrowed" because most plants probably moved into the area from elsewhere during and after the retreat of the glaciers. Thus, many species that are abundant in the Sandhills are also common outside the area. Some of these species, like blowout grass and the Sandhills milkweed, grow only on sand. Others, such as many of the other milkweeds and small soapweed (yucca) can also be found on many heavy but well-drained loess soils outside of the Sandhills.
The ecological communities of the Sandhills can vary tremendously, ranging from permanent wetlands to arid areas with almost desert-like conditions. Even within the wetland habitats, a great deal of variation occurs, ranging from permanent lakes and marshes, some of which are alkaline, to semipermanent and highly ephemeral marshes and wet meadows.
Of special importance are the many lakes and marshes of the Sandhills, which support the most significant waterfowl production area in Nebraska and one of the finest collections of water birds in the continental United States. The giant Canada goose, which disappeared from the Sandhills by about the beginning of the last century, was reintroduced by the Nebraska Game and Parks Commission in the 1970's. The mallard, blue-winged teal, pintail, and shoveler are the most common ducks in the Sandhills, but many other species also can be found.
Other water birds, including herons, grebes, terns, killdear, spotted sandpiper, least sandpiper, Wilson's phalarope, greater and lesser yellowlegs, and the American avocet are also common. In the late summer, the alkaline lakes in the western Sandhills produce an abundance of invertebrates, which provide food for large numbers of migrating shore birds. In one recent year, this area had one of the largest concentrations of American avocets in the entire United States.
The land-use pattern of the Sandhills has changed little during the past century compared to many other regions. Although cultivation has increased due in part to the advent of center pivot irrigation, livestock grazing is still the predominent land-use.
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Brought this up FYI. There have been several threads on the origins of the region.