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Soil lichen and moss cover and species richness can be highly dynamic: The effects of invasion by the annual exotic grass Bromus tectorum, precipitation, and temperature on biological soil crusts in SE Utah Biological soil crusts are an essential part of desert ecosystems throughout the world, as they are important in soil stabilization and soil fertility. Despite their importance, there have been few efforts to examine the population dynamics of the dominant species comprising these crusts or the effect of exotic plant invasions on these dynamics. In this study, we followed changes in lichen and moss cover for 8 years in plots dominated by native grasses or invaded by the exotic annual grass Bromus tectorum and across sites representing a range of land use histories. Our data showed that cover of both lichens and mosses can increase dramatically over short time periods, often going from just above 0% cover to as high... Categories: Publication; Types: Citation, Journal Citation; Tags: Applied Soil Ecology, Bromus tectorum, arid lands, biological soil crusts, collema, All tags... deserts, nitrogen cycles, population dynamics, Fewer tags Impacts of off-road vehicles on nitrogen cycles in biological soil crusts: resistance in different U.S. deserts Biological soil crusts are an important component of desert ecosystems, as they influence soil stability and fertility. This study examined and compared the short-term vehicular impacts on lichen cover and nitrogenase activity (NA) of biological soil crusts. Experimental disturbance was applied to different types of soil in regions throughout the western U.S. (Great Basin, Colorado Plateau, Sonoran, Chihuahuan, and Mojave deserts). Results show that pre-disturbance cover of soil lichens is significantly correlated with the silt content of soils, and negatively correlated with sand and clay. While disturbance appeared to reduce NA at all sites, differences were statistically significant at only 12 of the 26 sites.... Categories: Publication; Types: Citation, Journal Citation; Tags: Journal of Arid Environments, arid lands, biological soil crusts, microbiotic soil crusts, nitrogen cycles, All tags... soil surface disturbance, Fewer tags Surface disturbance of cryptobiotic soil crusts: Nitrogenase activity, chlorophyll content, and chlorophyll degradation Cryptobiotic soil crusts are an important component of semiarid and arid ecosystems. An important role of these crusts is the contribution of fixed nitrogen to cold-desert ecosystems. This study examines the residual effects of various intensities and combinations of different surface disturbances (raking, scalping, and tracked vehicles) on nitrogenase activity, chlorophyll content, and chlorophyll degradation in these soil crusts. Nine months after disturbance chlorophyll content of disturbed soils was not statistically different from undisturbed controls, except in the scalped treatments, indicating recovery of this characteristic is fairly quick unless surface material is removed. Differences in chlorophyll degradation... Categories: Publication; Types: Citation, Journal Citation; Tags: Arid Land Research and Management, Taylor & Francis, arid lands, cryptobiotic soil crusts, cryptogamic crusts, All tags... disturbance, microphytic crusts, nitrogen cycles, Fewer tags