The introduced Phellodendron amurense Rupr. (RUTACEAE) shows the potential to become a major invasive species throughout the northeastern United States. With confirmed invasion sites throughout southwestern Connecticut, New York City, and Philadelphia, Phellodendron appears to be spreading over much of the eastern United States from Virginia to Massachusetts. Despite this trend, Phellodendron is included in neither the Invasive Plant Atlas of New England (IPANE) or the Invasive Plant Council of New York State databases. Based upon data collected in invaded and uninvaded forest plots in a southwestern Connecticut forest stand, Phellodendron displays the ability to dominate areas based upon field measurements of density and dominance. Random forest plots show the importance value of Phellodendron to rank 14th (IV/2 = 5.86; IV/3 = 3.99) and invaded plots to rank 1st (IV/2 = 64.17) when frequency among plots is eliminated. While its invasive ability is evident, the mechanism of Phellodendron invasion ability is still poorly understood with the plant being found in a wide variety of habitats, yet with seed germination showing difficulty under controlled conditions (48 days < 4.0%).
This research is funded in part by the Connecticut Urban Forest Council.