Moss‐covered biodegradable weed barriers promote biocrust establishment but fail to suppress exotic plants.

Ecological restoration often requires exotic invasive plant control. In many ecosystems, reestablishment of biological soil crusts (biocrusts) is a desired restoration outcome because biocrusts enhance ecosystem function and may favor native plants over exotics. We sought to pair exotic plant suppression with biocrust restoration using a novel restoration material: biocrust‐covered weed barriers. We tested five different barriers, including three biodegradable weed barriers, one synthetic weed barrier commonly used in the study area, and burlap cloth, because it has previously been shown to be useful in biocrust establishment. We grew biocrust moss over the surface of each barrier type in a fog chamber. Each barrier type was attached to the ground in the field with moss on the underside of the barrier (moss‐down), the top, or not present. We monitored the establishment of moss biocrusts and exotic plants and the durability of the barriers. The most successful barrier type for biocrust establishment was burlap, but one biodegradable weed barrier made of maize‐derived polylactic acid (corn) promoted biocrusts, especially in the moss‐down position. Only the synthetic weed barrier suppressed exotic plants for two growing seasons. The corn barrier only partially suppressed exotic plants for one growing season. Less durable weed barriers were less able to suppress exotic plants. Though we failed to identify a biodegradable barrier that both stimulates biocrust recovery and suppresses exotic plants beyond one growing season, our results suggest that our goal may be attainable if more durable biodegradable weed barriers were used or created. [ABSTRACT FROM AUTHOR]