栃木県日光のニホンジカによる樹木剥皮

概要

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We investigated tree barking by sika deer (Cervus nippon) in Nikko, Tochigi prefecture in 1993, 1994, 1996 and 1997. In Omote Nikko area, 15.8% (28 species) of 2, 288 trees (52 species) were barked by sika deer in 1993, and it increased to 31.5% (19 specis) of 1, 038 trees (28 species) in 1994. In Oku Nikko area, 5.5% (11 species) of 397 trees (19 species) were damaged in 1994. Average size of tree surface damaged and ratio of heavily barked trees (over 50% of trunk circumference) increased significantly from 1993 to 1994 in Omote Nikko area (t-test, p<0.001, x^2-test, p<0.05 respectively). Sika deer preferably damaged Abies homolepis, Quercus mongolica, Clethra barbinervis and Chamaecyparis obtusa. Percentage average of damaged trees at the investigated sites exponentially increased with the lapse of year. Decrease of occurence of tree barking by the animals in high altitudinal area above 1, 500m since 1991 may be caused by the increase of snow accumulation that forced the animals move downwards. In a new wintering area of the southern slope of Mt. Nantai, the area with damaged trees expanded to high altitude from 1992 to 1996. On the other hands, at Akanuma, Oku-Nikko, mostly dominated by Larix leptolepis, the damage peaked in 1993 and then decreased rapidly until 1996.
1998-03-01