• Vegetation Development over 25 Years without Grazing on Sagebrush-dominated Rangeland in Southeastern Idaho

      Anderson, J. E.; Holte, K. E. (Society for Range Management, 1981-01-01)
      Data from permanent vegetation transects, established on the Idaho National Engineering Laboratory Site in 1950, were analyzed to determine what changes had taken place in the vegetation complex over the past 25 years in the absence of grazing by domestic livestock. Cover of shrubs and perennial grasses has nearly doubled. Shrub cover in 1975 was 154% greater than in 1950; this change was almost entirely due to increases in cover of big sagebrush between 1957 and 1965. Cover of perennial grasses increased exponentially over the 25-year period, from 0.28% in 1950 to 5.8% in 1975. This was paralleled by significant increases in density and distribution of the four most important grasses on the study area. The 20-fold increase in perennial grass cover has not been at the expense of the shrub overstory. There was no obvious correlation between trends for perennial grass cover and precipitation patterns. Rather, the exponential growth is believed to reflect the availability of seeds as formerly depleted populations increase in size. No evidence of seral replacement, as predicted by classical succession, was found. The data seem more consistent with the "initial floristics/relative stability" concepts of vegetation development.