OOS 54-2 - Restoration islands: Seeding biocrust in a sea of disturbance

The Mojave Desert is a challenging place for organisms to live and for restoration practitioners to repair because of high temperatures, low precipitation and edaphic factors. Often, practitioners will spread their efforts thinly across these disturbances and restoration is costly, labor intensive and too often unsuccessful. Restoration islands provide an alternative planning framework, where high intensity effort is focused on smaller ‘islands’ within the sea of disturbance. In these islands, practitioners focus resources on supporting restoration of biodiversity and function by stacking multiple methods that would be cost-prohibitive to deploy across entire disturbances. Ideally, these robust and self-sustaining islands will spread and connect in time. Biocrust communities are early colonizers, stabilizing soil, and promoting soil fertility and hydrology that influences colonization of vascular plants. Here we tested the hypothesis that restoration islands, including salvaged biocrust, with and without soil imprinting and soil tackifiers, would promote recovery of ecosystem function and plants on a decommissioned section of a gypsum mine near Las Vegas, Nevada, USA. We treated 3x9m plots with a factorial combination of soil imprinting and biocrust inoculation, as well as a split-plot treatment of psyllium husk (plant-based soil stabilizer) and seeded all plots with locally collected plants. We found that biocrust inoculation increased chlorophyll-A, a proxy for biocrust biomass, (F=365.6, p< 0.0001) with no positive impacts from psyllium application or imprinting. The increase in biocrust cover from inoculation was mirrored by an increase in exopolymeric substances (EPS; sticky sheath material created by cyanobacteria in biocrusts) in all three fractions (G-Fraction: F= 3.3, p< 0.0001, L-Fraction: F=35.4, p< 0.0001, T-Fraction: F=12.2, p=0.001) though EPS was surprisingly low given relatively high chlorophyll-a values. We did not find clear treatment effects on the plant community, but species diversity was overall much higher after treatment and we found individuals of several rare and endemic species in our plots, some likely from our seeding treatment and others volunteering from the biocrust inoculum’s seed bank. After 18 months, we found that biocrust addition had affected multiple soil stability metrics, suggesting that biocrust inoculation was already beginning to change the soil function with potential impacts on the plant community in the future. While longer term monitoring is needed to better understand the potential for the spread of our restoration islands and their influence on plant community, we found the biocrust inoculation alone is an effective tool for altering soil stability and increasing establishment of soil organisms.