Geographic pattern in the community structure of arboreal insects in beech forests in northern Japan

Forest ecosystems have high biodiversity with ecologically diverse animals and plants. The forest canopy supports high biodiversity, and canopy insects are important components owing to their high species richness and abundance. Although many studies have investigated the vertical stratification of arboreal insects, the formation process of geographic patterns in the arboreal insect community structure is not well understood. We analyzed arboreal insect communities in Japanese beech forests in northern Japan to examine their formation process of geographic pattern with geographic distance. We set eight study sites and collected insects monthly from June to September 2015 and 2016. We collected 2070 individuals from 479 species in 14 orders. We tested for nested structure in communities by distance and examined the correlation between the geographic distance and the dissimilarity of community structure. The insect community structure was nested by distance. When we classified insects by order into herbivore or carnivore, we found a positive correlation in herbivorous Hemiptera, while we were not able to find any correlations in other taxa. We collected a number of arboreal insect species that also occur in southern Japan at some sites. These results suggest that the arboreal insect communities in northern Japan change with geographic distance because they include taxa with a poor dispersal ability and some species from the southern beech forest along with the mountain area.