A practical technique for estimating deer appearance frequency and cedar sapling damage in young plantations protected by tree shelters in western Japan

ABSTRACT We developed simple practical methods to estimate deer appearance frequency and damage risk for cedar saplings protected by tree shelters, by using field signs such as browsed understory plants, debarked trees, and animal trails. The appearance frequency of the sika deer was recorded using camera traps at 29 clear-logged and young plantation sites in the Shikoku Island of western Japan. Field signs such as fecal pellets, footprints, animal trails, and browsed plants were recorded in three transects that were 2 m × 50 m each, located at the margins of the sites. Cubic regression analysis showed that the frequency of deer appearance could be predicted from the number of browsed plant species categorized into three ranks, that is, 0, 1, and ≥2 species. To use this method, plant species are not required for identification, as the user can simply judge whether browsed plants found in 5-m sections are all the same species or not. The damage of sheltered cedar saplings was assessed at 36 sites in the Kyushu and Shikoku Islands of western Japan, and surveys of deer field signs were also conducted. The proportion of heavily damaged saplings could be determined from the indices of binary summarized data of bark stripping and animal trails using a logistic regression model. The indices derived from the field signs will help forest managers to detect relatively low frequency of deer appearances and high risk of cedar sapling damage at a sheltered plantation in the western Japan.