Climate Change and Physical Disturbance Cause Similar Community Shifts in Biological Soil Crusts
Biological soil crusts (biocrusts)—communities of mosses, lichens, cyanobacteria, and heterotrophs living at the soil surface—are fundamental components of drylands worldwide, and their destruction dramatically alters biogeochemical processes, hydrology, surface energy balance, and vegetation cover. Impacts of physical disturbances on biocrusts (e.g., trampling by livestock and damage from vehicles) have been a long-standing concern, and concern is also increasing over the potential for climate change to alter biocrust community structure. Using long-term data from the Colorado Plateau, a recent study examined the effects of 10 years of experimental warming and altered precipitation on biocrust communities and compared the effects of altered climate with those of long-term physical disturbance (more than 10 years of replicated human trampling). Surprisingly, altered climate and physical disturbance treatments had similar effects on biocrust community structure. Warming, altered precipitation, and physical disturbance from trampling all promoted early successional community states. Although the pace of biocrust community change varied significantly among treatments, these results suggest that multiple aspects of climate change will affect biocrusts to the same degree as physical disturbance. This finding is particularly disconcerting in the context of warming, as temperatures for drylands are projected to increase beyond those imposed as treatments in this study.
Reference: Ferrenberg, S., S. C. Reed, and J. Belnap. 2015. “Climate Change and Physical Disturbance Cause Similar Community Shifts in Biological Soil Crust,” Proceedings of the National Academy of Sciences (USA) 112(39), 12116-121. DOI: 10.1073/pnas.1509150112.