PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Plant-soil feedbacks contribute to the persistence of Bromus inermis in tallgrass prairie.
Goergen, Erin*,1, Vinton, MaryAnn2, 1 Ecology, Evolution & Conservation Biology Graduate Group, Reno, NV, USA2 Biology Department, Omaha, NE, USA
ABSTRACT- Over the past 30 years, the C3 non-native plant, Bromus inermis (smooth brome) has been increasing throughout grasslands of the midwest. Invasion by this grass has resulted in local displacement of native tallgrass prairie grasses including Panicum virgatum (switchgrass). To determine if factors related to resource availability and plant-soil interactions were conferring a competitive advantage to smooth brome, field plots were set up under varying nutrient levels. Plots composed of a 1:1 ratio of smooth brome and switchgrass were set up in a restored tallgrass prairie and were randomly assigned one of three nutrient levels: 1) N added to increase available N 2) sugar added to reduce available N and 3) no additions to serve as control. In addition, soil nutrient status, soil respiration rates, and litter decomposition rates were monitored. Results indicate that smooth brome had greater tiller production on N enriched soils than did the native species, switchgrass. In contrast, smooth brome had a decreased tiller production on depleted N soils whereas switchgrass was not affected, suggesting that the native may have a competitive advantage on low N soils. Smooth brome plant tissue also had a lower C:N ratio and a higher decomposition rate than did switchgrass. These differences suggest a possible mechanism for the persistence of smooth brome in the tallgrass prairie – efficient recycling of nutrient rich litter under patches of smooth brome may confer a competitive advantage and allow it to invade and persist in remnant or restored prairies.
Key words: bromus inermis, invasion, plant-soil feedbacks, tallgrass prairie