Abstract
We investigated the effects of deer browsing on broad-leaved tree invasion after heavy thinning (47.5∼71.2% reduction in stem density) in fenced and unfenced plots in conifer plantations with a high population of sika deer (Cervus nippon). In fenced plots, a number of broad-leaved trees, which comprised mainly pioneer species, invaded and grew well after thinning; further, they exhibited a high survival ratio. However, in unfenced plots, the number of broad-leaved trees that invaded was lesser than that in fenced plots, and they exhibited a low survival ratio. Only a few broad-leaved trees survived for 2 years after thinning in unfenced plots. Thus, these results suggest that deer browsing strongly inhibited the invasion of broad-leaved trees after thinning. The deer density levels affecting broad-leaved tree invasion after heavy thinning should be evaluated, and easy methods to prevent the concentration of deer populations in thinned stands should be developed. Such studies will help achieve the conversion of conifer plantations to mixed conifer—broad-leaved forests in locations with high deer populations.
