Abstract
We tested if sugi (Cryptomeria japonica) seedlings grow vertically tall to avoid or reduce damage to the leader shoot due to feeding by sika deer (Cervus nippon). We investigated the growth of large-seedlings of different height (80–250 cm) and their damage status due to feeding by deer for six years after planting in a deforested site inhabited by deer. Larger seedlings (height: > 155 cm) were not seriously damaged (98%); no damage was observed on the leader shoots (78%), and they recovered from the reduction in height growth by the elongation of lateral shoots (20%) (i.e., alternative to damaged main shoot due to feeding by deer). Following this investigation, to further verify if large-seedlings are less susceptible to damage due to feeding by deer, we checked the height growth and damage status of 300 seedlings (average height: > 155 cm) that were planted in three other sites. Sixty percent of the seedlings escaped serious damage to the leader shoots due to feeding by deer and 7% of the seedlings recovered height growth by lateral shoot elongation, although the leader shoots were fed upon. On the other hand, damage due to stem breakage by deer was also observed in two out of three sites. “Stem breakage” percentage was observed in seedlings (27%), and particularly reached 77% in the most serious damaged site. However, 61% of these damaged seedlings also recovered height growth by lateral shoot elongation, as observed in the seedlings damaged due to feeding by deer. However, seedlings with stem breakage seemed to grow slower than non-damaged seedlings for one to two years. Thus, it is necessary to track the growth of damaged seedlings as part of sustainable forest management.
