| 要旨トップ | 本企画の概要 | | 日本生態学会第73回全国大会 (2026年3月、京都) 講演要旨 ESJ73 Abstract

シンポジウム S07-3 （Presentation in Symposium）

#### Woody plant community of a seasonally dry tropical forest in Madagascar【E】

*Yutaro FUJIMOTO（Kyoto Univ., FFPRI）, Takayuki KANEKO（Kyoto Univ.）, Hiroki SATO（Kyoto Univ.）, Ando Harilalao RAKOTOMAMONJY（Kyoto Univ., Univ. Mahajanga）, Rova Navalona ANDRIAMAHASETRA（Univ. Mahajanga）, Wataru NOYORI（Kyoto Univ.）, Yukako MONDA（Kyoto Univ.）, Shuichiro TAGANE（Kagoshima Univ.）, Natsuki KOMADA（Hiroshima Univ.）, Zo Lalaina RAZAFIARISON（Univ. Antananarivo）, Kaoru KITAJIMA（Kyoto Univ.）

In Madagascar, more than a quarter of its land is classified to dry region, with some remnants of seasonally dry forests protected as national parks. Ankarafantsika National Park in the northwestern dry region encompasses natural primary forests on white sand hills. What kinds of ecological characteristics do they have with the prolonged dry season and infertile sandy soil? This presentation shows the structure and diversity of a woody plant community in the white sand forest, based on a woody stem census in the first large-scale permanent plot in Madagascar. In 2019, we established a 15-ha long-term forest dynamics monitoring plot, in which all woody stems with diameter at breast height ≥ 5 cm were tagged, measured, mapped, and identified to species. Further surveys were conducted in its central 6-ha area, with the targeted minimal size of stems being down to 1 cm. For each species, we determined its leaf phenology type based on literature search and on-site observations: evergreen, imperfect evergreen, and deciduous. The 1-cm census revealed that the forest harbored 14,228 trees and 3152 lianas per ha, which were extremely high compared to other dry forests in the world. One of the reasons for the high density would be the absence of large-stem trees: the maximum was 46.9 cm, and 84.8% of stems were smaller than 5 cm. We recorded 160 tree species from 47 families and 50 liana species from 21 families, of which at least 82% were endemic to Madagascar. Leaf phenology type composition of the woody plant community showed its evergreen dominance. 57.5% of tree individuals, 48.9% of tree basal area, 55.3% of liana individuals, and 47.0% of liana basal area were evergreen. When we combined the imperfect evergreen type, which also has the conservative ecological strategy like the evergreen type, the percentages increased to 85.6%, 85.7%, 72.2%, and 76.4%, respectively. Those evergreen dominances would reflect adaptation of the woody plant community to the infertile soil. We will also share preliminary results of the on-going second census.

日本生態学会