Abstract
To investigate effects on the abundance and community structures of Orthorrhapha (predacious flies) inhabiting coarse wood debris (CWD) by the improvement cutting of natural forests, we report here abundances of predaicious flies emerged from CWD on the forest floor of the Yambaru. The volume, size and degree of wood decay were recorded and the emergence traps containing CWD were installed for collecting flies. Distribution of these CWD in the forests affected abundances of flies in each operated and non-operated stand. It caused different fly assemblages among the one year-old operated stands and seven year-old and older operated stands. Abundance of predacious flies, expecially dolichopodid flies, was positively correlated with the volume of CWD. Increasing the volume of CWD of the early stage of decay by cutting has indirect bottom-up effect on abundance of the dolichopodid genus Medetera via changes in abundance of bark beetles. We conclude that predacious fly diversity may best be maintained in the Yambaru through forest management practices that do not influent amount of CWD and make various sizes and degrees of wood decay present in a forest.
