Assessing commercial and early-seral arbuscular mycorrhizal fungi inoculation to aid in restoring sagebrush steppe shrubs

Authors: PRADO-TARANGO, DAVID - Oregon State University; MATA-GONZALEZ, RICARDO - Oregon State University; HOVLAND, MATTHEW - Oregon State University; Schreiner, Roger - Paul

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2021
Publication Date: 8/18/2021
Citation: Prado-Tarango, D.E., Mata-Gonzalez, R., Hovland, M., Schreiner, R.P. 2021. Assessing commercial and early-seral arbuscular mycorrhizal fungi inoculation to aid in restoring sagebrush steppe shrubs. Rangeland Ecology and Management. 79:87-90. https://doi.org/10.1016/j.rama.2021.08.001.
DOI: https://doi.org/10.1016/j.rama.2021.08.001

Interpretive Summary: Arbuscular mycorrhizal fungi (AMF) influence plant communities and their use may increase the success of native plant establishment in restoration. However, little is known of how AMF may alter restoration of native shrubs in the sagebrush steppe ecosystems prevalent in western United States. A study was conducted to test if commercially available AMF inoculum would colonize the roots of three native sagebrush shrubs and an invading grass species and whether or not this would improve the growth of these plants. The AMF inoculum only resulted in a very low level of root colonization of the invasive grass, and failed to colonize any of the sagebrush shrubs in sterilized soil. Inoculation had no influence on root colonization in live soil and all plants were colonized by the AMF already present in live soil. Plants grown in sterilized soil grew better than those grown in live soil. These findings indicate that use of AMF inoculation for restoration must be tested prior to its use in the real world, and that other organisms in the soil appear to inhibit plant growth of native sagebrush plants and an invasive grass.

Technical Abstract: Arbuscular mycorrhizal fungi (AMF) are drivers of plant communities as they influence plant competition by increasing plant root absorptive surface outside of the nutrient depletion zone. In some grassland systems, mycorrhizal inoculation is an important tool for ecological restoration. However, a lack of research using AMF in sagebrush steppe communities implies a need for more assessments of its efficacy. Here, we assessed the effect of a commercial inoculum for its ability to colonize roots and influence growth of seedlings of three native shrubs (Artemisia spp.) and one exotic grass (Taeniatherum caput-medusae) common to sagebrush steppe. Before testing the inoculum on the species of interest, its viability expressed as the rate of inoculum required to ensure root colonization was examined using Trifolium incarnatum in sterilized soil. A factorial greenhouse experiment was then conducted to evaluate the four species of interest when grown in either live or sterilized (autoclaved) field soil form a disturbed (early seral) site. Inoculation resulted in root colonization in T. incarnatum but failed to colonize any of the sagebrush steppe species in sterilized soil and had little to no influence on colonization in live soil. The plants were colonized by AMF in live soil, but plants grown in autoclaved soil had greater biomass. Our results reveal differential ability of a commercial inoculum of AMF to colonize roots of Artemisia spp. and T. incarnatum, a possible pathogenic effect of live field soil, and the need to assess the efficacy of inoculum of AMF prior to field application.