松枯れに伴う宮島の森林植生の変化

抄録

Phytosociological vegetation mapping was conducted in 1974 and 1980 to study the successional change of community types after pine damage in and around the Natural Botanical Garden of Hiroshima University on Miyajima Island. Change of the occupying area of each community was mainly due to disturbance by selective cutting and transportation of dead pine trees. The most distinctive increase of the area was observed in the community type at an early successional stage, Typcal variant of Symploco-Pinetum densiflorae myrsinetosum seguinii, which showed a 10.2% increase during the six year period. The most declined community, which showed a 12.4% decrease at a rather late successional stage, was Neolitsea aciculata variant. The transition among the community types commonly occurred as follows : from Rhododendron kaempferi variant to Typical variant, from Neolitsea aciculata variant to Rhododendron-Neolitsea transitional community and finally to Typical variant. This finding implies that the change of the vegetation was caused by a retrogressive succession rather than by a progressive one. Change of the vegetation in 1974-1980 in relation to the microtopography was also discussed.