Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Sullivan, Alexis [1], Bunn, Rebecca [2], Cheeke, Tanya [3].

Impact of invasion by annual grasses on mycorrhizal inoculation potential in a grassland ecosystem.

Invasive plant species are one of the top drivers of change in grassland ecosystem function and can decrease above and belowground biodiversity. In the Pacific Northwest (PNW) land managers and government agencies are concerned with the invasive winter annual grass Ventenata dubia (African wiregrass). Since its introduction in the 1950s, V. dubia has successfully invaded grasslands across the PNW, including endangered grassland ecosystems such as the Palouse Prairie. Fewer than 1% of native Palouse Prairie remnants exist and this ecosystem is under ongoing threat of extinction due to land-use change and invasive species. The invasion of V. dubia has had negative impacts on the species richness and diversity of native plants in grassland habitats in the PNW. This has led to a decline in biodiversity and abundance of native plants that are important to local Indigenous peoples and wildlife habitat. Despite its rapid invasion and impact on native plant communities and in agricultural systems, little is known about V. dubia’s influence on soil abiotic characteristics, and its interactions with soil microbial communities.
To evaluate the impact of V. dubia invasion on above and belowground communities in an endangered grassland, we used the Palouse Prairie as a model system and assessed native plant species diversity, arbuscular mycorrhizal (AM) fungi inoculation potential, and soil nutrient availability across four field sites in the Palouse. We set up replicate 4x4m plots across the four sites (n=36) that varied in percent cover of invasive and native plants and labeled them native, invasive, and transition. To determine the inoculation potential of AM fungi in native, invasive and transition plots, we conducted a mycorrhizal inoculation potential assay in a greenhouse experiment. Plants were grown in soil inocula collected from the rhizosphere ‘types’: native Pseudoroegneria spicata (blue bunch wheatgrass) in native dominated plots, soil inocula collected from the rhizosphere of invasive V. dubia in invasive dominated plots, and soil inocula collected from the rhizospheres of both focal species (P. spicata and V. dubia) in the transition plots. To determine whether soil nutrient availability varied among native, invasive, and transition plots, composite soil samples were collected from each plot and assessed for the availability of nitrogen (NO3- and NH4+), phosphorus (P), and potassium (K). To determine if plant community composition corresponds with mycorrhizal inoculation potential, or availability of NO3-, NH4+, P, or K, we will use field survey data on the percent canopy cover of individual plant species in each plot in a nonmetric multidimensional scaling analysis.
We hypothesize that plots dominated by native plant species will have higher mycorrhizal inoculation potential, greater native plant species diversity, and lower nutrient availability compared to invaded plots. Understanding V. dubia’s impact on both above and belowground systems will aid in the management and control of the increasing threat of this invasive plant species to grassland ecosystems.

1 - Washington State University, School of Biological Sciences, 2710 Crimson Way, East, 103, Richland, WA, 99354, USA
2 - Western Washington University , Environmental Sciences, 516 High Street, Bellingham, WA, 99354, USA
3 - Washington State University, School Of Biological Sciences, 2710 Crimson Way, Richland, WA, 99354, United States

arbuscular mycorrhizal fungi
non-native species
native species
invasive species
Palouse Prairie
plant-soil interactions.

Presentation Type: Oral Paper
Number: SYM2003
Abstract ID:608
Candidate for Awards:None

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