Forest fragments are subject to many stressors including exotic plant invasions.
These invasions can potentially affect tree seedling performance, nutrient cycling, species composition, and future tree communities. A common invasive species found across the northeastern United States is Rubus phoenicolasius (wineberry). Wineberry is a spiny woody shrub native to Asia and was intentionally introduced to the United States for raspberry cultivation. The objectives of this study were to test wineberry invasion impacts on forest community dynamics and function. We performed this study at the Hutchison Memorial Forest, located in Franklin Township, New Jersey. We examined the response of planted tree and shrub seedlings in the center, edge, and adjacent to patches of wineberry. We surveyed transects of wineberry for herbaceous species and abundance; and measured abiotic factors in patches of wineberry including rates of decomposition. Seedlings were planted in 1 m2 plots along a 12 transects through wineberry patches and monitored for growth and survival over the 2015 growing season. Species richness was recorded for 1 m2 plots along 15 additional transects. Nylon tea bags were filled with either green tea or dried wineberry leaves, measured for initial mass, buried for ninety days, and measured for change in mass.
This study found a significant decrease in native cover among center plots compared to control plots (p = 0.0159). Additionally, exotic cover (controlled for wineberry) increased with more wineberry cover. Plots located in the center of the wineberry patches had 1.19 times more species richness than the control plots. When comparing the center, edge, and control plots there were significant differences in plant communities. The average Sorensen’s distance for control plots was 0.6833, edge plots 0.7292, and center plots 0.6954 (MRPP: T = -7.0406, A = 0.0399, p< 0.0001). Control and edge plots were significantly different from center plots in terms of plant communities. Finally, there was a significant difference in loss of mass for green tea leaves compared to wineberry leaves. Wineberry leaves lost on average 1.81 times more mass than the control leaves. Overall there is an effect wineberry on forest community dynamics and further study can helpt to inform management practices.