Long-term invasion by cheatgrass often increases availability of soil N and P thereby fostering increased competitive ability. We designed an experiment to test if cheatgrass (Bromus tectorum, exotic annual), Snake River wheatgrass (Elymus wawawaiensis, native perennial), and crested wheatgrass (Agropyron cristatum, exotic perennial) all benefit from this elevated nutrient availability. Soils from three cheatgrass invaded and adjacent non-invaded areas in northern Nevada were freshly-collected. Replicates were sown to each of the grasses and grown for 70 days. Following harvest, above-ground and root biomass were recorded and nutrients in above-ground plant tissue were quantified as well as natural abundance 15N. Soils were homogenized and analyzed for several nutrient availability indexes. Above-ground biomass of cheatgrass and crested wheatgrass averaged over 2 times greater in soil conditioned by cheatgrass invasion relative their growth in non-invaded soil; biomass of Snake River wheatgrass was statistically similar in invaded and non-invaded soils. For all plants tested, tissue P concentration was greatest when grown in the invaded soils and used a greater proportion of the bicarbonate-extractable P pool in the invaded soils than non-invaded soils. Cheatgrass and crested wheatgrass growing in invaded soils used a significantly greater proportion of the 30-day mineralizable N pool relative the non-invaded soil; Snake River wheatgrass used similar proportions in the two soil types. Natural abundance of 15N of plant tissue indicated that Snake River wheatgrass utilized more isotopically negative 15N fraction from the invaded soil than did cheatgrass or crested wheatgrass. Overall, our data suggest that the native perennial Snake River wheatgrass uptakes available N in the invaded soils differently than does cheatgrass and crested wheatgrass.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.