自然教育園に生育するスダジイ巨木群の現状とその保護について : 都市林の保護に関する生態学的考察

概要

論文の詳細を見る
Since 1965 ecological observations and surveys have been carried out on the old huge Shii-tree, (Castanopsis cuspidata var. sieboldii)-stands grown in the National Park for Nature Study, Central Tokyo. The Shii-stands in the park are climax or climaxlike (Bladhio-Shiietum sieboldii) and consist of many evergreen plants such as Eurya japonica, Fatsia japonica, Aucuba japonica, Kadsura japonica. Ardisia japonica, Dryopteris erythrosora, Ophiopogon japonicus. Liriope platyphylla etc. as well as Castanopsis cuspidata var. sieboldii. The stands and their costituents grow very naturally, but now under bad influences of urban environment. Thus, not only the Shii-trees but also other many tree species in the park are gradually reducing their vitality(Photo 2-5). In the results of autecological studies, the number of old trees in the stands counted 234,and their size distribution ranged mainly from 1.30 to 3.40 meter in circle at breast height(Fig.1). The maximum tree reaches 6.70 m.(Photo 1.). The health of all trees in the forest are judged using following standard classification. The health index of growth condition for Castanopsis cuspidata var. sieboldii is as follows. V Leaf coverage entirely, more than 800% of canopy. IV Leaf coverage between 80-60%. Death of twigs attracting attention. III Leaf coverage 60-40%. Withering reaches boughs. II Leaf coverage 40-20%. Barks exfoliating, and infected by parasites(Fungi). I Leaf coverage less than 20%. The stand wholly brightend. The histogramm of the health indices classified above and spatial distribution for all the old Castanopsis-trees are shown in Figures 6 and 7 respectively. The phytosociological observations show a gradual invation into the stands, shrubby and climbing plants such as Morus bombycis. Paederia scandens var. mairei, Dioscorea tokoro, Mallotus japonicus etc. following the degradation of the upper tree layer (Tab. 1.), and the forest floor becomes like a jungle (Photo 11.). To conserve this area in a good conditon, several managing and controlling plans such as sprinkling of water against dryness of the soil and fertilizing and transplanting young trees into the stands in place of the weakened trees. However these artifitial treatments have more or less risks to disturb the balances of biota in the natural communitv. The most important and safe management is to protect and controlling the marginal communities.

著者

奥田重俊
横浜国立大学

自然教育園に生育するスダジイ巨木群の現状とその保護について : 都市林の保護に関する生態学的考察

スポンサーリンク

概要

著者

関連論文

スポンサーリンク