Permanent quadrats were established inside and outside of grazing exclosures on various vegetation types in the Jornada Experimental Range between 1915 and 1932, in order to measure shifts in dominant species composition. Between the establishment of the quadrats and 1981, the dominant species in many of the vegetation types had changed to be more shrub dominated, but the most apparent changes occurred in the black grama (Bouteloua eriopoda) vegetation type where black grama was completely absent from all plots where it was previously dominant. In some cases, dominant species in livestock exclosures did not change while in others, large shifts in species composition were recorded, indicating that livestock grazing may not be the only selection pressure in this ecosystem. Since 1932 increasing shrub species have increased the diversity of vegetation on the desert grasslands in the Jornada Experimental Range, and these changes appear to be a result of both grazing pressure and changing environmental conditions.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.