Invasion by the annual grass, Ventenata dubia does not impact mycorrhizal fungal abundance in an endangered prairie

One of the challenges in ecological restorations is that some native plant species are difficult to reestablish in disturbed or invaded landscapes. Some invasive plant species negatively impact soil biota, such as arbuscular mycorrhizal (AM) fungi, which can lead to feedbacks that facilitate their dominance in a landscape. The winter annual grass, Ventenata dubia, is rapidly invading North American grasslands, however, the effect of its invasion on AM fungi, plant communities, and soil properties is not well known. In a greenhouse and field experiment, we tested (1) whether the abundance of viable AM fungal propagules is altered in soil invaded by V. dubia; (2) how plant community composition, species richness, and/or diversity may be impacted by V. dubia; and (3) whether soil properties, such as pH and organic matter (OM) vary across invasion levels. We found that the effect of V. dubia on the abundance of mycorrhizal propagules varied among sites and did not reduce the species richness or diversity of resident plant communities. Higher canopy cover of V. dubia was associated with higher soil pH and OM, which suggests either V. dubia invasions change these soil properties, or that V. dubia preferentially invades these areas. Our findings suggest V. dubia does not consistently alter above-or belowground communities; however, the potential link between V. dubia invasions and soil pH and OM deserves additional investigation. A better understanding of how invasive annual grasses impact plant and soil communities will be useful in informing restoration efforts in landscapes impacted by invasive species.