A non-native species, Oplismenus hirtellus ssp. undulatifolius, common name wavyleaf basketgrass (WLBG) was recently identified in eastern deciduous hardwood forest where it establishes dense mats carpeting the understory. WLBG spreads locally through vegetative reproduction and over a longer range via its uniquely sticky seeds, which are easily translocated by hikers and wildlife, particularly deer. Since its discovery in 1995, it has spread from a single county park in Maryland to several natural areas in six counties as well as parts of Shenandoah National Park, Virginia. Understanding the biotic and abiotic features that constitute suitable habitat for this species and combining this information with forecasting models will help assess the potential impact of this species and identify areas where WLBG is likely to invade. We used a paired plot design (N=30 pairs) to investigate the environmental characteristics associated with presence of WLBG. These plots were located in areas that, to our knowledge, are among the initial invasion sites of this species and have very dense WLBG cover. Uninvaded and invaded plots were placed within 10 m of each other with the assumption that WLBG had ample opportunity to colonize the site and lack of invasion was due to soil or other environmental factors. In each plot we measured species richness and percent cover, litter depth, percent ground cover , soil moisture and conductivity, canopy openness, slope face and gradient, photosynthetic active radiation (PAR) and sunfleck intensity, and recorded any nearby disturbances (i.e. deer paths).
Results/Conclusions Results/Conclusions
A multiresponse permutation process (MRPP) was used to determine if uninvaded and invaded plots fell into distinct groups based on the measured variables. Our results show that at this local scale, there is no significant difference in any of the environmental variables measured between the invaded and uninvaded plots. Therefore we can conclude that patchiness of this species is due to either environmental variables not measured in this study or the assumption that WLBG has had ample time to invade was not met. Further research is planned to investigate the importance of additional local scale variables, such as mycorrhizal interactions, and regional scale climate variables in WLBG distribution. Identification of the factors controlling WLBG distribution is vital to determine the level of threat posed by WLBG and to identify other habitats and regions at high risk of invasion.
