Document Type

Thesis - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)


Plant Science


Investigations on aspects of seasonal wetland forage potential were conducted in eastern South Dakota. The quantity and quality of the standing crop of vegetation in 6 seasonal wetland communities were assessed at the end of the growing season in 1983 and in 2 seasonal-wetland-dominated basins and their associated uplands (native mixed-grass prairie) over the growing season in 1985. Crude protein (CP), ash, detergent fiber, and in vitro digestible dry matter (IVDDM) values were measured on the above-ground material of whitetop [Scolochloas festucacea (Willd.) Link], slough sedge (Carex atherodes Spreng.), burred (Spargnaium eurycarpum Engelm.), and smartweed (Polygonum amphibium L. var. emersum Michx.) at intervals during the growing seasons of 1984 and 1985. Concurrent measurements of the total nonstructural carbohydrate (TNC) content of below-ground material of these 4 species were also made. An additional 27 species were collected during the summer season of 1984 and 1985 for CP, ash, and IVDDM analyses. Season-long comparisons of wetlands and uplands show that, on an area basis, seasonal-wetland-dominated basins produce higher standing crops of forage than uplands in a native mixed-grass prairie situation. The large late-season standing crop estimates (679 to 1146 g·m‾²) in 6 seasonal wetlands, as well as values in the literature, suggest that most seasonal wetlands probably do yield higher standing crops (on a single cutting basis) than native mixed-grass prairie or cultivated cool-season grasses. However, the digestibility of the dominant wetland forages is lower, on the average, than native upland forage. Several subordinate forb species were found to have high IVDDM and CP values during mid-summer and may be potential candidates for a wetland forage breeding program. Seasonal-wetland-dominated basins should be utilized early in the growing season to optimize forage quality. CP and IVDDM contents of whitetop and slough sedge were comparable to most grasses at similar phenological stages. At mid-summer, however, the nutritional quality of these 2 species is low and would make a hay adequate only as a base roughage. Whitetop nutritional quality is very poor during the latter portion of the growing season, while the quality of slough sedge is maintained at an adequate level for a longer period. TNC reserves in below-ground material of these 2 species are lowest during the approximate periods of tillering and flowering (early June). Utilization at seed-fill for whitetop and just post-seed- fill for slough sedge will avoid the period of low TNC reserves and yet yield an acceptable quality forage. Burreed, on the other hand, is a species that may be considered for control in seasonal wetlands. The TNC content of below-ground material of burred is at its lowest near the onset of flowering. Therefore, control measures should be implemented at that time. If utilized early in the growing season, seasonal wetlands are capable of producing some good quality forages. If utilized in the latter part of the growing season, forage quality may be low but yields are high. With appropriate supplementation, these forages could be used as roughages in domestic livestock rations. Utilization of wetlands for forage production is a use more compatible with other wetland functions than is the artificial draining of them and planning to annual crops.

Library of Congress Subject Headings

Wetlands – South Dakota
Forage plants – South Dakota
Wetland plants – South Dakota


Includes bibliographical references (pages 142-159)



Number of Pages



South Dakota State University


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