Biological soil crusts in grazed and ungrazed Wyoming sagebrush steppe

Abstract

Biological soil crusts are regarded as an indicator of healthy landscapes. To understand the response of biological soil crusts to grazing in northern sagebrush steppe, we examined nine Artemisia-dominated sites in Wyoming where livestock have been excluded for 32–45 years. Using two common sampling methods (20 m line transects and 0.25 m 2 quadrats) we determined biological soil crust cover and richness inside and outside exclosures. Total biological soil crust cover did not differ inside and outside the exclosures at any of the nine sites, regardless of monitoring method. Cover of biological soil crusts using the transect method ranged from 2% to 8% inside and 1% to 6% outside the exclosure. Cover of biological soil crusts using the quadrat method ranged from 2% to 11% inside and 2% to 9% outside the exclosure. Fruticose lichen cover was greater outside the exclosure at two sites (Poison Spider and Lander Ant) using the quadrat method. Both methods show a decrease in moss outside exclosures when assessed across all sites. Lichen and moss richness ranged from 5 to 15 species at each site. Fourteen of the 34 species collected throughout the sites were found only at one of the nine sites, and they did not all occur together or at the same site. Our results suggest that 32–45 years of grazing removal has not increased soil lichen cover but did increase moss cover inside exclosures. Distinguishing biological soil crusts by morphological groups aided recognition of differences that would not be apparent in an analysis by species.