Restoration of Ecosystem Function by Soil Surface Inoculation with Biocrust in Mesic and Xeric Alpine Ecosystems

Abstract

Biocrusts are soil surface assemblages of lichens, bacteria, fungi, and bryophytes that support key ecosystem processes in alpine environments. Their role in carbon and nitrogen cycling is critical to soil pedogenesis. Establishment of biocrusts after disturbance events is an important first step in restoring ecosystem function. However, our understanding of active restoration of alpine biocrusts, as well as how environmental factors affect ecosystem processes associated with early succession, is poor. In a field experiment at two alpine sites (a xeric and a mesic site), we monitored microclimatic conditions and assessed function of mature biocrusts. We also examined the influence of inoculation with mature biocrusts and fertilization on the recovery of biocrusts in disturbed alpine soils. Biocrust cover and soil surface nitrogen fixation were enhanced by inoculation after 12 weeks at the mesic site. However, at the xeric site biocrust cover increased while nitrogen fixation declined. Restoration of dry and cold alpine environments presents many challenges and recovery of ecosystem services may require additional restoration techniques and longer timelines. Improved understanding of the community composition of alpine biocrusts and their developmental trajectories over time will assist with effectively using biocrusts to promote recovery of ecosystem processes in disturbed alpine environments.