Identification of the Competitive Relationship between Aggressive Plant Humulus japonicus and Perennial Native Plants

Abstract

Humulus japonicus, designated as an ecosystem-disturbing plant by the Ministry of Environment of Korea in 2019, is an annual plant with fast and long-growing vines known to harm the ecosystem, such as indiscriminately appearing after river construction, harming the landscape. Long vines with thorns climb and cover the surrounding native plants to destroy vegetation along the river. This study aimed to identify the competitive relationship between H. japonicus and perennial native plants to figure out ecological information, such as the mechanism of invasion of the riverbank by H. japonicus. Three native perennial species, Miscanthus sacchariflorus, Aster yomena, and Pennisetum alopecuroides, were used for the study. A two-year common garden experiment was conducted for this study. In the first year, H. japonicus and perennial plants were introduced and grown together, and in the second year, H. japonicus was introduced after the perennial plants had already been established. The number of leaves, shoot length, specific leaf area (SLA), shoot dry mass of all species, and root dry mass and survival rate of H. japonicus were measured and analyzed for each competitive relationship. The results of the study showed that in the first year, H. japonicus significantly reduced the number of leaves of M. sacchariflorus and P. alopecuroides, and the shoot dry mass of M. sacchariflorus and P. alopecuroides (P<0.01). In the second year, the survival rate of H. japonicus competing with A. yomena was significantly reduced (P<0.05). The results of this study revealed the adverse effect of H. japonicus, which are recently considered plants requiring management, and showed that A. yomena may interfere with the settlement of H. japonicus. For the sustainable stability of the river plant ecosystem, it is necessary to suggest an ecological control plan that can prevent the appearance of aggressive plant H. japonicus and our results can be used as basic information for the biological control of H. japonicus.