The impact of bamboo cutting on species diversity and community structure of ground beetles (Coleoptera; Carabidae) at Riparian Forests in the Inukami River

Abstract

To elucidate the possible impact of bamboo culm thinning on ground beetle species diversity, we carried out a survey of species diversity and community structure of ground beetles (Coleoptera: Carabidae) using unbaited pitfall trapping in riparian forest dominated by broad-leaved trees and bamboos along the Inukami River in Shiga Prefecture, Japan. Ground beetles were captured once a week at four experimental squares each with different bamboo culm density treatments; all culm cutting (AC: 0 culm/m²), heavily thinned (HT: 0.5 culm/m²), lightly thinned (LT: 0.7 culm/m²) and abandonment (AB: 1.8 culm/m²), during July to December, 2010. A total of 2,739 individuals of ground beetles belonging to 33 species were captured at the four squares. Species richness of ground beetles was the highest in the AC square and the lowest in the AB square. Individuals of many species increased and individuals of very few species decreased by bamboo cutting. In addition, detrended correspondence analysis revealed that the species composition at the AC square differed from the other squares. The characteristic species in the AC square were Harpalini spp., Chlaenius variicornis and C. naeviger. The former two are known as open habitat species, contributing to the higher species richness and the characteristic species composition. These results showed that although there was no replication in present study, removal of bamboo culms in broad-leaved forest had a positive impact on the species richness and community structure of ground beetles primary due to the increase of the open habitat species.