Disturbance of shrub-steppe soils and alterations in plant cover may affect the distribution, size and activity of soil microorganisms and their ability to biogeochemically cycle essential nutrients. Therefore, the soil microbial biomass and activity and selected soil enzyme activities were determined for two arid ecosystems, an undisturbed perennial shrub-steppe and annual grassland, which was initially shrub-steppe and has been an annual grassland since the disturbance caused by farming ceased in the 1940s. Soils were sampled at 0?5 and 5?15 cm depths beneath sagebrush (Artemisia tridentata Mutt.), bluebunch wheatgrass [Elytrigia spicata (Pursh) D.R. Dewey] and cryptogamic soil lichen crust at the perennial site and beneath downy [...]
