Annual grass invasion is associated with differences in the community structure and abundance of biocrusts and arbuscular mycorrhizal fungi.

Interactions between biocrusts and arbuscular mycorrhizal (AM) fungi may increase plant resilience to environmental stress in native grasslands. When non-native plants invade, they may have cascading effects on soil biota and their interactions, destabilizing grassland ecosystems. In a field survey we assessed the % cover and composition of biocrusts in plots varying in % cover of the invasive annual grass, Ventenanta dubia (Native, Transition, Invaded plots). We used field-collected soil as inocula in a glasshouse experiment to test whether the abundance of viable AM fungal propagules differs under biocrusts compared with bare soil, or across invasion levels. We used 18S rRNA gene sequencing on field-collected soil to test whether the structure of the AM fungal community differs under biocrusts versus bare soil across invasion levels. Invasion by V. dubia was associated with lower biocrust cover, distinct biocrust community structure, lower abundance of viable AM fungal propagules below biocrusts, and distinct AM fungal community structure with invasion. Our results support broader United Nations Sustainable Development Goals focused on the protection and restoration of terrestrial ecosystems. A better understanding of the interactions among plants, biocrusts, and AM fungi is important for mitigating the impacts of invasive species and informing grassland restorations.