A phytotelmatum, which is a water-filled tree hole, is a specific microhabitat in a deciduous forest, and establishes a detrital food web inside. To examine the effects of the height of tree holes and understory vegetation on the aquatic communities, we used artificial containers as a model of tree holes.

We selected two neighboring study plots with and without understory vegetation in a deciduous (Quercus serrata) forest located in eastern Japan. We placed 204 artificial containers with a distilled water and leaf-litter on the trees of the different heights: upper (4.0 m), middle (1.5 m), and low layers (0.5 m). We collected 30 containers and sorted macroinvertebrates every month during June to December 2011.

The containers of a low layer had more abundant of plant litter, and more frequent of a subsidy of drowned invertebrates than those of other layers. Moreover, the aquatic macroinvertebrates were also abundant in the samples of a low layer. However, these tended to be higher densities in the samples with drowned invertebrates regardless of height. We suggest that a subsidy of drowned invertebrates is more important for the aquatic macroinvertebrates than the environmental factors such as the height of tree holes and understory vegetation.