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International Journal of Forestry Research
Volume 2015 (2015), Article ID 687506, 9 pages
http://dx.doi.org/10.1155/2015/687506
Research Article

Effects of Deer Grazing on Vegetation and Ground-Dwelling Insects in a Larch Forest in Okutama, Western Tokyo

School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 229-859, Japan

Received 30 July 2014; Revised 3 December 2014; Accepted 22 December 2014

Academic Editor: Alejandro Solla

Copyright © 2015 Hodaka Yamada and Seiki Takatsuki. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Sika deer (Cervus nippon) have experienced a rapid increase in the Japanese archipelago. Although the effects of deer grazing have been widely studied, the indirect effects have received little attention. Using an eight-year-old deer exclosure in western Tokyo (Japan), we studied the direct effects on plants and the indirect effects on insects and microenvironments. Plant biomass was 14 times higher inside the exclosure than outside. Shrubs (e.g., Aralia elata and Hydrangea paniculata) and trees (e.g., Symplocos sawafutagi and Clethra barbinervis) were more abundant inside, whereas only unpalatable trees in poor condition grew outside (e.g., Pterostyrax hispida and Cynanchum caudatum). In the summer months, the maximum temperature was 8–10°C higher outside the exclosure and humidity was lower. Soil movement was 80 times more pronounced outside than inside. These results suggest that the abiotic environment became less stable for ground-dwelling insects. Carabid beetles were less abundant outside than inside, suggesting that deer grazing reduced plants and subsequently lowered habitat quality for these beetles. In contrast, carrion beetles, dung beetles, and camel crickets were more abundant outside. The increase in these insects is attributed to the availability of deer feces and carcasses and is a direct effect of deer presence.