In central North America, scattered small ponds, some that dry up in late summer, the "prairie potholes", provide habitat for nesting waterfowl. These were formed by the passage of the glaciers. In some regions, prairie potholes have been drained to allow the area to be cultivated.
Grasses are the cornerstone of this environment. They have adapted to the heavy loss of moisture during the day by becoming partially nocturnal, opening their pores in the evening. The rough surface of their narrow leaves helps cut loss of water to the wind. They recover quickly from grazing since they grow from their lower parts and transfer the stored energy created by photosynthesis below ground.
The rivers in these areas have been used, in many cases over-used, for irrigation. Large dams also disrupt the natural renewal of nutrients in the river's floodplain.
Trees are scattered sparsely through these areas. Some have established themselves on rocky outcrops and along rivers. Treed areas, sheltered from the sun, provide habitat for wildlife that has not fully adapted to the harsher conditions of the open areas. Trees such as cottonwoods found along rivers have come to rely on seasonal flooding. They provide habitat for insects and so also insect-eating birds.
Image Source: U.S. Bureau of Land Management
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