Grassland invaders and their mycorrhizal symbionts: a study across climate and invasion gradients. Issue 6 (19th February 2014)

• Record Type: Journal Article
• Authors: Bunn, Rebecca A.; Lekberg, Ylva; Gallagher, Christopher; Rosendahl, Søren; Ramsey, Philip W.
• Is Part Of: Ecology and evolution. Volume 4:Issue 6(2014:Jun.)
• Page Start: 794
• Page End: 805
• Publication Date: 2014-02-19
• Subjects: 454‐sequencing -- arbuscular mycorrhizal fungi -- Centaurea stoebe -- community structure -- plant invasion -- plant–soil interactions -- Potentilla recta; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.917
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Controlled experiments show that arbuscular mycorrhizal fungi (AMF) can increase competitiveness of exotic plants, potentially increasing invasion success. We surveyed AMF abundance and community composition in Centaurea stoebe and Potentilla recta invasions in the western USA to assess whether patterns were consistent with mycorrhizal‐mediated invasions. We asked whether (1) AMF abundance and community composition differ between native and exotic forbs, (2) associations between native plants and AMF shift with invading exotic plants, and (3) AMF abundance and/or community composition differ in areas where exotic plants are highly invasive and in areas where they are not. We collected soil and roots from invaded and native forb communities along invasion gradients and in regions with different invasion densities. We used AMF root colonization as a measure of AMF abundance and characterized AMF communities in roots using 454‐sequencing of the LSU‐rDNA region. All plants were highly colonized (>60%), but exotic forbs tended to be more colonized than natives ( P < 0.001). We identified 30 AMF operational taxonomic units (OTUs) across sites, and community composition was best predicted by abiotic factors (soil texture, pH). Two OTUs in the genera Glomus and Rhizophagus dominated in most communities, and their dominance increased with invasion density ( r = 0.57, P = 0.010), while overall OTU richness decreased with invasion density ( r = −0.61, P = 0.006). Samples along P. recta invasion gradients revealed small and reciprocal shifts in AMF communities with >45% fungal OTUs shared between neighboring native and P. recta plants. Overall, we observed significant, but modest, differences in AMF colonization and communities between co‐occurring exotic and native forbs and among exotic forbs across regions that differ in invasion pressure. While experimental manipulations are required to assess functional consequences, the observed patterns are not consistent with those expected from strong mycorrhizal‐mediated invasions. Abstract : In an observational field study, we looked for patterns consistent with mycorrhizal‐mediated plant invasions such as (1) exotic plants harboring different AMF abundance and/or community composition than native plants, (2) native plants having altered AMF associations in the presence of exotics, and (3) shifts in AMF abundance and/or community composition correlating with plant invasiveness. We observed significant, but modest, differences in AMF colonization and communities between co‐occurring exotic and native forbs and among exotic forbs across regions that differ in invasion pressure. While experimental manipulations are required to assess functional consequences, the observed patterns are not consistent with those expected from strong mycorrhizal‐mediated invasions.