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Ecological Studies at the Woodworth Study Area

Upland Vegetation at the Woodworth Study Area

Mavis I. Meyer*
U.S. Fish and Wildlife Service
Denver Federal Center
Denver, CO 80225

Upland habitats on the Woodworth Study Area (WSA) are mostly croplands, seeded grasslands, and native grasslands. The croplands undergo annual tillage, seeded grasslands are fields planted with a mixture of perennial grasses and legumes, and the native grasslands have no history of tillage. Shelterbelts, roads, and an abandoned gravel pit area make up the remainder of the uplands.

The long range plan for managing the upland vegetation was to develop seeded cover attractive to nesting waterfowl, to restore native grass stands, and to maintain existing native prairie (1). By 1970, more than 500 acres of former cropland were seeded into mostly non-native cool-season grasses and legumes. The primary grass species were intermediate wheatgrass (Agropyron intermedium), tall wheatgrass (A. elongatum) and slender wheatgrass (A. caninum), and the legumes were alfalfa (Medicago sativa) and yellow sweetclover (Melilotus officinalis). Two fields were seeded into basin wild rye (Elymus cinereus). The WSA provided the landbase to experiment with native grass seedings during the mid 1970's. About 15% of the area was seeded with native grasses by 1980. The principal cool-season species were green needlegrass (Stipa viridula) and western wheatgrass (Agropyron smithii). Some fields were over-seeded with warm season species including switchgrass (Panicum virgatum), big bluestem (Andropogon gerardi), and Indian grass (Sorghastrum nutans).

Cattle grazing, prescribed burning, and non-use were used to manage the existing native prairie. Several permanently marked vegetation transects were established, along which data on visual obstruction, canopy cover, and plant species composition were collected. The transects were monitored annually from 1975-1985 to evaluate treatment effects on nesting cover. Permanent photo stations and other visual observations provided supplemental information.

The native prairie is divided into five classes: mixed grass, shrub, tall grass, broad-leaved forb and tree (2). The mixed grass is dominated by blue grama (Bouteloua gracilis), native mixed grass (Bouteloua gracilis, Stipa comata), and Kentucky bluegrass (Poa pratensis) communities. The shrub class is divided into two communities, low shrub dominated by wolfberry (Symphoricarpos occidentalis), and tall shrub dominated by chokecherry (Prunus virginiana). Tall grass communities are dominated by little bluestem (Andropogon scoparius), big bluestem (Andropogon gerardi), indian-grass (Sorghastrum nutans), and prairie cordgrass (Spartina pectinata). The brood-leaved forb community is primarily maximilian sunflower (Helianthus maximiliani) and Canada goldenrod (Solidago canadensis). Native trees, cottonwood (Populus deltoides) and willow (Salix spp.) occur in the gravel pit area.

The WSA is located in a vegetation transitional zone where the taller grasses of the drift plain intermingle with mixed and short grasses of Missouri Coteau. The mosaic of different soils and moisture regimes provide the foundation for over 280 upland plant species. Although the WSA is small, it remains a critical research area for natural resource interests.

1.  Higgins, K. F., Kirsch, L. M., Klett, A. T. and Miller, H. W. (1992) Waterfowl
         Production on the Woodworth Station in South-central North Dakota, 1965-1981.
         U.S. Fish Wildl. Serv. Resour. Publ. 180.

2.  Meyer, M. I. (1985) Classification of native vegetation at the Woodworth Station, 
         North Dakota.  Prairie Nat. 17,167-175.

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