Investigation of the Ecological Impact of Japanese Knotweed (Polygonum cuspidatium) on the Riparian Plant Community and Its Potential Use as a Food Source for Macro-Invertebrates

Elaine Langone Center, Terrace Room

This study focused on two sites along the lower West Branch of the Susquehanna: the Riverfront Park in Loyalsock Township and the park surrounding Montoursville Airport in Montoursville Borough. Data were collected throughout the summer and fall of 2015. At each site, plant density data was collected using a transect method and tree density data was collected using the Point-Quarter method. Tests on the soil at each location included percent organic content, particle size, nematode count, and arthropod identification. The above-ground biomass of Japanese knotweed and the percent organic content of those samples were found at the Riverfront Park site. The allelopathic mechanism of Japanese knotweed will be tested in a lab experiment, conducted in the late fall. To determine whether Japanese knotweed is a good food source for aquatic macro-invertebrates, a project was conducted to collect data on both leaf decomposition rates and macro-invertebrate populations. Leaf packs, comprised of pin oak, silver maple, or Japanese knotweed leaves and a brick placed in a mesh bag, were incubated for varying periods of time in Mill Creek, located in Loyalsock Township. Leaf surface area was measured and recorded before and after incubation to quantify the decomposition rates of the different species. Macro-invertebrates were collected off the leaf packs and identified to analyze the different populations colonizing each species. Ergosterol can be used to quantify the amount of fungal biomass on a leaf which indicates the palatability of the leaf for macro-invertebrates so an analysis of ergosterol content was also conducted using High Pressure Liquid Chromatography (HPLC).