The Vegetation of Remnant Grasslands in the Loessial Region of Northwestern Kansas and Southwestern Nebraska

Abstract

The purpose of this study was to inventory and analyze the com- positional structure of the vegetation and also to attempt to, discern causal environ- mental factors influencing species distributions within the loessial region of north- western Kansas and southwestern Nebraska. The study was limited to areas of native vegetation that had not been disturbed by burning, grazing of domestic livestock, periodical mowing or by other activities of man for a period of not less than 15 or 20 years. The family composition of the vascular plants in the loessial region indicated that 23.5% of the vegetation was in the family Gramineae, while Compositae, Fabaceae, and Euphorbiaceae were represented by 21%, 10.3% and 5.6% respectively. The dominant grasses and forbs in the loessial area varied as a result of remnant stand exposure, slope, and position on slope. Blue grama (Bouteloua gracilis) and big bluestem (Andropogon gerardi) were dominant on dry level uplands while very-dry steep upper slopes afforded side-oats grama (Bouteloua curtipendula) and little bluestem (Andropogon scoparius) with grea:test success. All four of these species were prominent on gentle upper slopes and gentle lower slopes, which were con- sidered dry-mesic in moisture status. The mesic lowlands supported stands of big bluestem and western wheatgrass (Agropyron smithii). Most species of forbs and grasses were distributed in response to a topographic gradient, which influenced site moisture conditions.