North American Prairie Conference


Date of this Version



Published in Prairie Pioneers: Ecology, History and Culture: Proceedings of the Eleventh North American Prairie Conference, August 7-11, 1988, Lincoln, Nebraska (Lincoln, NE 1989).


In 1936, vegetation analyses were conducted on repurchased federal lands in the Powder River Basin of eastern Wyoming. During the summer of 1987 the 74 remaining plots of 97 originally established on a 2.6 km2 (1 mi2) area in Converse County were re-examined. Both surveys were conducted with the "square foot density procedure." During the past 51 years, vegetation abundance increased significantly on the saline upland site as a result of the interactive effects of favorable long-term weather patterns, annual grazing by livestock and wildlife, and reduced fire. Total vegetation cover increased significantly (P < 0.05) from 3% in 1936 to 11 % in 1987, including a threefold increase for all grasses and a fourfold increase for all woody species. A negligible change occurred for all forbs. A shift in the cover composition occurred with grasses decreasing from 52% to 44% and non-grass species showing a corresponding increase. All growth forms, except shrubs, gained wider distribution over the study period, especially succulents and annual grasses. Continuation of current management practices probably means that this range will not return to a short grass-dominated prairie.