Effects of sika deer browsing on soil mesofauna in a thinned Japanese cypress plantation

We examined the indirect effects of sika deer (Cervus nippon) overabundance on soil mesofauna in a thinned plantation. We compared the understory vegetation, environmental conditions at the forest floor, and soil mesofauna inside and outside of a fenced area established at a plantation of Japanese cypress in central Japan about 6 years after thinning. Deer browsing had reduced the volume of understory plants outside the fence; this tended to not cause a reduction in the litter mass and an increase in the soil bulk density, but caused an increase in the relative photosynthetic photon flux density reaching the forest floor. As a result, the relative humidity at the forest floor was lower outside the fence than inside. The abundances of detritivores and fungivores and predators in the soil mesofauna declined significantly in areas with deer. This could be due to desiccation in the litter layer inhabited by many detritivores and fungivores and predators that are sensitive to changes in moisture conditions. Thus, deer browsing had a negative effect on the soil mesofauna as well as on the aboveground fauna in the understory vegetation.