Root climbers are a group of lianas which typically climb the host tree using adhesive roots and do not compete with the host for light. They are relatively more abundant in high-latitude forests and were recently documented to have no harmful effect on their host trees. Although previous studies have examined the direct negative effects of lianas on their host trees, little is known about potential indirect effects via effects on the animal and plant communities. Here, we aimed to determine the effects of root climbers on the animal and plant community composition of their host trunk and whether these alterations indirectly affect host trees. To answer these questions, we compared the invertebrate community, herbaceous plant presence, moss cover and herbivory rates in more than 22 pairs of host and control trees in cool-temperate forests in Hokkaido, Japan. We selected Quercus crispula Blume and Hydrangea petiolaris Sieb. et Zucc. as the study species. Generalised linear mixed models (GLMMs) were used to determine the influence of lianas on tree trunk communities and host trees. Our results showed that the presence of root climbers increased the abundance of Araneae and herbaceous plants and reduced the abundance of Formicidae on host trees, implying a reduction of herbivory on hosts. These results imply that liana presence may reduce the herbivory rate on the host tree, potentially by altering the trunk animal and plant community structure. Our results have implications for the understanding of the effects of lianas on host trees and their function in high-latitude forests.
Keywords: Araneae; Cool-temperate forest; Formicidae; Functional diversity; Woody vine.