PARENT SESSION
Wednesday, August 9, 8:00-11:30 am
COS 47 - Invasive species III: impacts on native species, communities, and ecosystems
Ballroom A, Ballroom Level, Cook Convention Center
Presiders: D Blumenthal and J Martin
Influence of Bromus tectorum on arbuscular mycorrhizal fungi in a restoration context.
Rowe, Helen1, Brown, Cynthia*,1, Paschke, Mark1, 1 Colorado State University, Fort Collins, CO
ABSTRACT- Bromus tectorum (cheatgrass, downy brome) has invaded approximately 40,000,000 hectares of rangelands in the United States, reducing native species diversity and transforming habitats. Cheatgrass can now be found in montane ecosystems that are important habitats for wildlife and livestock. In addition to well understood mechanisms by which cheatgrass gains competitive advantage, recent studies show cheatgrass is associated with changes in arbuscular mycorrhizal fungi (AMF) communities. We test the idea that cheatgrass is associated with depleted mycorrhizal communities by implementing relevant restoration strategies of AMF and sucrose additions with seeding. Sucrose additions are a proven tool for initiating conditions that accelerate successional change; reduced plant available N suppresses annual plant species, including cheatgrass, and gives perennial species a competitive advantage. Because most perennial plants respond to AMF with increased growth compared to no AMF, if the AMF community is depleted, the addition of AMF with sucrose should have an additive effect on perennial establishment and growth. As expected, sucrose amendments reduced annual plant cover, increased perennial seedling establishment, and minimally increased perennial forb cover. Cheatgrass was inhibited by both sucrose and AMF amendments. However, native perennial species did not respond to the AMF additions. Despite the need to provide adequate AMF inocula at times, restoration sites in which native perennial plants persist may already have sufficient AMF. Although reduced mycorrhizal inoculation potential was found in the presence of cheatgrass, existing AMF can be adequate for successful recruitment of perennial species, at least where native species coexist with cheatgrass.
Key words: invasion, AMF, rangeland