Facilitating restoration of degraded biological soil crusts using mixed culture inoculation

Abstract

In arid and semiarid ecosystems, the biological soil crust (biocrust) community is ecologically critical and it is advantageous to restore damaged biocrust. Coastal sage scrub (CSS) is a unique and imperiled valuable habitat. At present, studies of biocrust restoration in CSS habitat do not exist. This study examined the feasibility of isolating and culturing a mix of endemic CSS cyanobacteria and green algae to inoculate native CSS soil, thereby facilitating recovery of disturbed biocrust. To gauge whether inoculation increases soil function, we measured culture growth, chlorophyll a, extractable polysaccharides, and stability. Growth of biocrust organisms and increases in functionality were compared among three inoculation treatments (mixed culture, ground biocrust, and uninoculated control) with either autoclaved or non-autoclaved native soil to determine the extent that native crust organisms can regrow without inoculation. A novel genus and species of cyanobacteria was isolated and classified as Trichotorquatus maritimus. The mixed culture included a green alga, possibly Chlamydomonas callunae. Mixed inoculum added to non-autoclaved native soil significantly improved the soil functions. After two months, the mixed inoculum increased chlorophyll levels, soil stability, and increased extractable polysaccharides. It may be possible in the future to restore biocrust in CSS using mixed culture inoculation.