MERI

"NOVEL DEFENSES IN A SEA OF CLONES": RESEARCH INTO THE ROLE OF ROOT EXUDATES AND THE ROLE OF CLONAL COMPETITION AMONG NATIVE AND EXOTIC GRASSES

Abstract: The New Jersey Meadowlands today are a “sea of grasses” where native and exotic species meet and interact. Hence, our two research projects deal (a) with ecological and biochemical aspects of root exudates of a group of predominantly exotic grasses and (b) with the role of genetic identity in competition between native (Spartina patens) and an exotic grass clones (Phragmites australis). In the first project we characterized the strong presence and ecological function of a phenolics-degrading root enzyme (PPO) that is present in high concentrations only in species of the grass genus Bromus, a genus with a worldwide recognized, strong invasion potential. Our results so far lend support to the hypothesis that this enzyme enables the invaders to cope with alleolopathic compounds of competitor species and therefore act as a type of novel defense aiding in the invasion process. We are currently exploring whether this root enzyme can be utilized in remediation of phenolic-polluted soils and we experimentally testing whether this enzyme can be useful in combating other, more problematic invasive species that are successful due to their own phenolic exudates. In the second project we investigate whether remnant clonal populations of the native grass Spartina patens differ in their competitive ability in the face of the invasion by the European clone of Phragmites australis. We found indications that larger clonal stands differ in border zone characteristics from smaller remnant stands and we see indications that these differences are also reflected in genetic identity, as indicated by DNA analysis. We are embarking on field trials that are designed to test for the role of clonal genetic differentiations that will render restoration efforts more successful. The main goal here is to identify clones that compete best with non-native species.