Porcelain Berry (Ampelopsis brevipedunculata), Bushkiller (Cayratia japonica), and Virginia-Creeper (Parthenocissus quinquefolia) in Interspecific Competition

Abstract Porcelain berry and bushkiller are confamilial, exotic, perennial vines in the Vitaceae family that are considered nuisance/invasive weeds of natural and riparian areas in the eastern United States. To better understand the competitive abilities of these aggressive weeds, greenhouse competition experiments were conducted on cuttings of porcelain berry, bushkiller, and Virginia-creeper, a native member of the Vitaceae family. Plants grown singly or in combination were monitored for stem growth and biomass production. In this research, porcelain berry and Virginia-creeper exhibited similar rates of stem growth, whereas bushkiller grew taller and faster than either of the other species. Porcelain berry stem growth was reduced in competition with bushkiller. All three species exhibited reduced stem biomass when grown with both other species. Root biomass of porcelain berry and Virginia-creeper were not affected by competition, but bushkiller, which produced the heaviest roots, exhibited reduced root biomass when grown with both other species. Porcelain berry root length was reduced by competition with both other species, but neither Virginia-creeper nor bushkiller root lengths were affected by competition. These results indicate that bushkiller is likely the strongest competitor of the three species studied. In these experiments, porcelain berry was less aggressive and vigorous than bushkiller but was similar to Virginia-creeper. Nomenclature: Bushkiller,Cayratia japonica (Thunb.) Gagnep. ; porcelain berry, Ampelopsis brevipedunculata (Maxim.) Trautv. ; Virginia-creeper, Parthenocissus quinquefolia (L.) Planch. Management Implications: Porcelain berry and bushkiller are exotic, perennial, climbing vines in the grape family. Both species were likely introduced into the United States for horticultural purposes and have proven to be aggressive invaders in some areas. Porcelain berry is common throughout the eastern United States, whereas bushkiller is only known to occur in five states. One aspect of managing invasive species is to understand the threat posed by that species to other members of the invaded community. Competition studies are commonly used to measure the ability of a plant species to effectively garner resources, such as light, water, and nutrients, in the presence of competing neighboring plants. An understanding of the growth and competitive capabilities of these species may be helpful to determine regulatory policy in states with limited or no infestations of these species, for management recommendations of infested areas, and to predict potential environmental effects on invaded areas. Greenhouse competition studies between porcelain berry, bushkiller, and Virginia-creeper, a native perennial member of the grape family, indicate that bushkiller is by far the most successful competitor of the three, acquiring greater stem length and more stem and root biomass than the others. Porcelain berry showed similar growth and competitive abilities as Virginia-creeper, with the exception of having significantly higher inflorescence production than either other species. The results indicate that, although porcelain berry is a troublesome weed in many areas and may contribute intense propagule pressure, bushkiller has the potential to become a more significant threat, and infestations of this plant should be eliminated as soon as they are discovered.