Abstract
The overabundance of large herbivores is now recognized as a serious ecological problem. However, the resulting ecological consequences remain poorly understood. The ecological effects of an increase in sika deer, Cervus nippon Temminck (Cervidae), on three insect groups of beetles was investigated: ground beetles (Carabidae), carrion beetles (Silphidae), and dung beetles (Scarabaeidae and Geotrupidae) on Nakanoshima Island, Hokkaido, northern Japan. We collected beetles on Nakanoshima Island (experimental site) and lakeshore areas (control site) and compared the species richness, abundance, diversity index, and community composition of beetles between the sites. Results showed that although both species diversity and abundance of carabid beetles were significantly higher at the lakeshore site, those of dung and carrion beetles were higher at the island site. It was additionally observed that abundance of larger carabid beetles was higher at the lakeshore site, whereas that of small-sized carabid beetles did not differ between the lakeshore and island sites. For dung beetles, abundance of smaller species was higher at the island site, whereas that of large species did not differ between the lakeshore and island sites. Abundance of two body sizes (small and large) of carrion beetles were both higher at the island site. Overall, the findings of this study demonstrated that an increase in deer population altered the insect assemblages at an island scale, suggesting further changes in ecosystem functions and services in this region.
Highlights
The overabundance of large herbivores is recognized as one of the serious ecological issues worldwide, especially in the northern hemisphere (Gill 1992, Côté et al 2004, Takatsuki 2009)
Because of overgrazing at the island site, the structure of understory vegetation and the forest floor differ between the island and lakeshore sites (Fig. 1), with the island site dominated by Senecio cannabifolius Less. (Asteraceae); Sagina japonica (Sw.) Ohwi (Caryophyllaceae); Pachysandra terminalis Siebold et Zucc. (Buxaceae) and Chloranthus serratus (Thunb.) Roem. et Schult. (Chloranthaceae), which sika deer find unpalatable (Takahashi and Kaji 2001, Miyaki and Kaji 2009)
The current study demonstrated that an increase in sika deer at Lake Toya significantly changed both the abundance and species richness of beetle species belonging to three different taxonomic groups
Summary
The overabundance of large herbivores is recognized as one of the serious ecological issues worldwide, especially in the northern hemisphere (Gill 1992, Côté et al 2004, Takatsuki 2009). There is mounting evidence demonstrating the serious consequences of large herbivore overabundance on forest ecosystems (Takatsuki 2009, Foster et al 2014). As large herbivores selectively browse palatable species, browsing has negative effects on understory structure and species composition (Rooney 2009, Martin et al 2011, Tanentzap et al 2011). It has been reported that smaller herbivorous invertebrates are negatively influenced by large herbivore overabundance because of interspecies competition for food resources (Gómez and González-Megías 2002, Wheatall et al 2013). Browsing results in the degradation of habitat for invertebrates and birds (Stewart 2001, Allombert et al 2005, Chollet and Martin 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
