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Management Problems of the Vegetation on the Sheyenne National Grasslands

Llewellyn L. Manske PhD

Associate Range Scientist
North Dakota State University
Dickinson Research Extension Center

The prairie grouse range on the Sheyenne National Grasslands consists of gently rolling and undulating hummocks (small hills) with relief usually of only 5 to 10 feet. The native vegetation is diverse and is expressed in distinct belts on each hummock. The mixed grass prairie exists on the summit and shoulder slopes of each hummock. The tall grass prairie exists on the back slope and extends into the foot slope. The switchgrass community occupies the lower portion of the tall grass prairie on the foot slope. The sedge meadow community exists on the toe slope of each hummock. The grassland communities of the Hummocky and Deltaic Plains Habitat Associations are comprised of 41% mixed grass prairie, 37% tall grass prairie, and 22% sedge meadow community. These grassland plant communities change over a relatively short distance which makes the management requirements quite complex. The natural growth pattern for the highly productive vegetation on the foot and toe slopes is to grow fast and start senescence in the early portion of the grazing season. Cattle generally do not graze these areas in mid and late season. Grazing pressure is then concentrated on the summit, shoulder, and back slopes. The foot and toe slopes have a high water table and the vegetation is less vulnerable than the dryer summit and shoulder slopes. Manipulation with summer mowing and prescribed spring burning of the sedge meadow community returns the vegetation to an early growth stage which is very nutritious (Erickson, Barker, and Haugse 1978) and highly selected by cattle when coordinated with the grazing rotation dates (Manske and Barker 1981). Livestock can be attracted to the lowland areas for the first and second year after prescribed burning and mowing. This lowers the effective grazing pressure on the vegetation of the summit, shoulder, and upper portions of the back slopes. It is very important for the health and production of the mixed grass prairie and the tall grass prairie community to manipulate the sedge meadow communities with prescribed burning and mowing.

The sedge meadow communities that are not manipulated with burning or mowing develop accumulations of standing old growth which decrease and retard growth of current years graminoid tillers and provides an environment for shrub species to grow. Cattle grazing is not effective on reduction of shrub densities except when shoots are very young and have not developed wood. Mowing can be used to reduce aboveground portions of young shrub plants when the stem thickness is not very great nor the plants very tall but mowing machines can not be used effectively on old shrubs that are tall and have thick woody stems. Prescribed spring burning can be used to reduce aboveground portions of shrubs when they are young or old. Most of the shrub species that grow in the sedge meadow communities sprout suckers from the root after the aboveground portions are removed. Repeated aboveground defoliation treatments are required to effectively reduce the density of shrubs by depleting carbohydrate stores in their roots and eventually weaken the plant until it dies. The sedge meadow plant community requires defoliation management of fire, mowing, and grazing in order to maintain it in a productive, healthy condition.

Shrub encroachment is a problem on the mixed grass prairie and tall grass prairie communities and also requires defoliation management with fire, mowing, and grazing to keep them productive and healthy.

Leafy spurge is a monumental problem noxious weed that has invaded the Sheyenne National Grasslands and requires diligent annual cultural and chemical management to keep it in check. Biological reduction of this weed by several selective insect species appears to have considerable promise for the future. It will be a very long time until the population numbers of the insects can be built up to match the huge number of leafy spurge plants. The cultural and chemical management treatments should be continued until there is convincing evidence that the insect numbers are causing reductions in the total leafy spurge population.

Literature Cited

Erickson, D.O., W.T. Barker, and C.N. Haugse. 1978. The feeding value of native grasses in the Sheyenne National Grasslands. North Dakota Farm Research Bimonthly Bulletin. Vol. 36(1):8-12.

Manske, L.L. and W.T. Barker, 1981. The prairie grouse on the Sheyenne National Grasslands, North Dakota. NDSU Research Report, Fargo, N.D. 238p.