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Prairie Basin Wetlands of the Dakotas:
A Community Profile

Chapter 1 -- Introduction

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1.4 -- Distribution and Abundance of Wetlands

During the 1960's and 1970's, 2.3 million temporary, seasonal, and semipermanent wetland basins, with a total area of 1.04 million ha, were estimated to be present in the Prairie Pothole Region of the Dakotas (Ruwaldt 1975: Stewart and Kantrud 1973; H.A. Kantrud, unpubl. data). The estimates were based on relatively small numbers of randomly sampled plots. Approximate basin numbers and areas by water regime were 698,000 temporary (113,000 ha), 1,474,000 seasonal (583,000 ha), and 127,000 semipermanent (345,000 ha). These basins were estimated to compose 84.8% of the area and 89.3% of the number of natural basins in the region; subsequent drainage and filling has further reduced the number of wetlands.

Distribution of these wetlands correlates with the distribution of various glacial landforms (for descriptions see Section 2.1). In both Dakotas, the greatest proportional area of semipermanent wetlands occurs in areas of dead-ice and terminal moraine, whereas the greatest proportional area of temporary and seasonal wetlands occurs in ground moraine and lake plain. The largest proportional area of semipermanent wetlands is found in the Missouri and Prairie Coteaus, whereas the less permanent wetlands are best represented in the Glaciated Plains and Lake Plains (Figure 3).

Density of basins can be >40/km² in some areas of dead-ice moraine or ground moraine, but the average is much less for the entire region, because some glacial and postglacial landforms contain few basins.

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Figure 3. Major physiographic regions in the Prairie Pothole Region of the Dakotas.

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Previous Section -- Classification of Prairie Basin Wetlands
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Next Section -- Geology

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