Biological soil crusts (biocrusts) are soil surface communities of bryophytes, lichen, cyanobacteria, algae and associated heterotrophs, which cover a large fraction of many dryland ecosystems. Biocrusts contribute many ecosystem functions including soil stabilization, water regulation, carbon and nitrogen cycling and may be important for co-occurring vegetation communities. Yet across drylands globally, biocrusts have been severely impacted by anthropogenic disturbances, including livestock grazing and trampling, off-road vehicle use, and industrial development. Because biocrusts are composed of slow growing organisms, with limited dispersal distances, one perspective has been that degraded biocrust only recover on timescales of decades to centuries; thus minimizing disturbance is the primary method for preserving biocrusts. Yet, because of the scale of biocrust degradation across the southwest US, and the criticality of the ecosystem functions biocrusts provide, increasing effort has been placed on methods of biocrust restoration. In general, restoration practices revolve around protecting an area from repeated disturbance and inoculating the soil surface with target organisms or communities. One potential problem with this approach is that recent climate manipulation experiments (warming and altered precipitation) indicate extreme negative impacts of warming and subtle precipitation shifts on key late-successional elements of biocrust communities.
Biocrusts were collected from eight locations, representing the range of mean annual temperature, precipitation, and precipitation seasonality characteristic of drylands of the Western US, spanning a geographic range from central Idaho to southern Arizona. Biocrusts were grown under experimental greenhouse conditions (high and low watering treatment, full sun and 50% shade cloth) to evaluate different methods of increasing the growth of moss and lichen. Low watering and full sun increased the relative and absolute growth of lichen, while high watering and shade cloth preferentially stimulated moss growth. After 2.5 months in the greenhouse, biocrust was collected and used to inoculate plots at a degraded rangeland site on the Colorado Plateau near Moab, Utah. Plots were set up in 10 blocks of 9 plots each, where each plot contains biocrust inoculum from one geographic origin, and each block is subjected to heating (+3 C) via infrared lamp, or ambient temperature (5 blocks per treatment). We measured biocrust cover, biogeochemical cycling of C, N and P, soil stability, soil surface temperature and moisture. The first measurement phase of the experiment will be completed in May 2017, and we will present results from our greenhouse trials as well as this first measurement phase.Background/Question/Methods