To investigate the impact of sika deer (Cervus nippon) on the forest ecosystem and resident life in a mountainous area of the Chugoku District, we conducted a vegetation survey and an awareness questionnaire survey. The study area was located in Fukutomi-Cho, Higashi-Hiroshima, Hiroshima Prefecture. We set a study plot in a secondary forest composed mainly of Chamaecyparis obtusa and broadleaf trees and recorded the damage by sika deer (herbivory and fraying) on each tree within the plot. There were 180 individual trees belonging to 14 species in the study plot, about 3.3% of which had fraying scars and 7.2% had feeding scars. The analysis indicated that sika deer had a significant preference for C. obtusa as fraying trees and Clethra barbinervis as food. Plant coverage of the forest floor was small and dominated by Pieris japonica, which is known to be unpalatable to deer.
The awareness questionnaire survey revealed that the most common damage by sika deer was crop damage. The survey also indicated that the residents felt that sightings of and damage by sika deer had increased in the last 10–20 years. The residents noted that they had managed their forests for various purposes but stopped the management partly due to lifestyle changes and prevalence of pine wilt disease, which caused a significant decline in matsutake mushrooms. The results suggest that the increase of unmanaged forests provided sika deer with their habitat, and that the deer moved from the overgrazed forests to human habitation in search of food.