伊豆諸島御蔵島で発見された分布東限のイスノキ林
Eastern extreme stand of Distylium racemosum forest discovered on Mikura-jima Island, Izu Islands, eastern Japan

Reiji NOZAKI, Yoshinobu HOSHINO, Tatsuhiro ISOGAI
1996 Shokusei Gakkaishi  
E139 ' 37り, in the southern Izu Islands . This stand extends c , 4 ha in area , and is established at 400 to 550 ma . s , L in a valley of the northeastern facing slope of the island . Phytosociological study showed that it belongs tQ the Carici − Castanopsietum sieboldii OHBA 1971, a CastanoPsis − type association indigenous to the Izu Islands . It falls into Symplocetosum , a high altitudinal subunit of the association , and finally , into the P . ra 'emeosuma facies . Symplocetosum is
more » ... locetosum is distinguished by man } ・ differential species common to Daphniphyllo − Trochodendretum aralioidis OHBA l971, a wind − exposed scrub established on the summit zone of the island . Consequently , D . racemo . sctm facies has the intermediate flora of botb associations . In the survey of individual trees in the transects , D . racemosum showed an inverse J − shaped distribution for DBH size class on a stable site . Moreover , they have many saplings and seedlings in the understQry . The maximum size Qf I) . racemosttm reaches to 90 cln in DBH and about 20m in height . These facts suggest that this stand has fully matured and has reached a climax stable state , To examine the geographical distribuヒiQn of D . racemoserm forest in Japan, a distributiQn map was compi 【 ed fr て )m various sources 、 Though Mikura − lima Island is about σ. 3eO km east of the continuous distribution ranges of D . racemosum forests of southwestern Japan, the altitudinal range of ヱ ) . racemosum forest in this island occupies nearly an equal position as that Qf southwestern Shikoku and southern Kyushu, which are considered to be 出 e
doi:10.15031/vegsci.13.11 fatcat:6u2sm27adfgbvk3d6q7cfgqclm