Differences in above-ground resource acquisition and niche overlap between a model invader (Phragmites australis) and resident plant species: measuring the role of fitness and niche differences in the field

Identifying the mechanisms that result in a “high impact” invasive species can be difficult. Coexistence theory suggests detrimental better predicted by incorporating both niche differences and fitness than examining overlap alone. Specifically, should take up shared limited resources more efficiently their neighbouring resident species. While there is clear evidence Phragmites australis successfully displacing species, remains few field studies attempt to quantify difference between P. it field. We measured photosynthetic performance (carbon assimilation rate, δ13C, water use efficiency, biomass, light compensation point, saturation point), canopy height interception of photosynthetically active radiation, three freshwater wetland (Calamagrostis canadensis, Carex aquatilis, Typha spp.) growing with or without aboveground interspecific competition. Invasive intercepted had higher average larger region compared Resident plant showed significant decrease when competition high probability onto space australis. These results provide ability reduce availability required resource over season, while exhibiting likely contributes directly its success North American wetlands.