Tuesday, August 4, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Background/Question/Methods
Large-statured invasive grasses are among the most notorious invaders of wetland and riparian systems in North America. In eastern North America, European common reed (Phragmites australis) genotypes are super-abundant in most wetland habitats where native genotypes were once present. In the west, common reed invasion has occurred in only a few locations, but there is an abundance of suitable habitats. Specialist exotic aphids (Hyalopterus pruni) prefer to feed on native reed genotypes and cause significantly more damage than they do to the exotic genotype. A Gulf Coast common reed genotype, not previously known to be invasive, is expanding rapidly in riparian corridors and agricultural ditches and canals in the southwest, displacing native populations and possibly facilitating the spread of H. pruni into native stands. The objectives of my research are to 1) identify native, exotic, and Gulf Coast P. australis populations throughout the southwest US and use these data to build a GIS database for the management of exotic and Gulf Coast genotypes and conservation of native genotypes, 2) determine the distribution of (H. pruni) and quantify population sizes and subsequent damage to native and invasive genotypes in this region, and 3) evaluate the potential for the invasive Gulf Coast genotype to facilitate the spread of H. pruni into native P. australis populations.
Results/Conclusions
Genetic analysis shows that native, exotic, and Gulf Coast genotypes are present throughout the southwestern United States with an often high degree of genetic structuring over this broad spatial area. Exotic P. australis was also found in several new locations suggesting that this invasion is progressing and many suitable habitats are at risk. Gulf Coast P. australis spread into artificial and natural desert wetland systems appeared to be driven by human modification of water resources. Exotic aphids were found in all exotic and Gulf Coast populations sampled, as well as native populations within 100km of these sites, but not in isolated seeps and springs in montane wetlands. In a common garden experiment, I am currently investigating the relative effects of invasive P. australis competition and H. pruni feeding on native P. australis growth to determine the impact multiple invasions will have on native populations.
