Canopy Multilayering and Woody Species Diversity of a Subtropical Evergreen Broadleaf Forest, Okinawa Island.

v. ill. 23 cm.QuarterlyWoody species diversity and the spatial distribution of trees in a subtropical evergreen broadleaf forest on a silicate substrate, Okinawa Island, were investigated to determine the forest’s architectural stratification. The forest stand consisted of four architectural layers. The values of Shannon’s index H0 and Pielou’s index J 0 tended to increase from the top layer downward, except for the bottom layer. The lower layers contained many species relative to their smaller height ranges. High woody species diversity of the forest depended on small trees. This trend of species diversity was different from that of forest on a limestone substrate on Okinawa Island, where high woody species diversity depended on large trees. Conservation of small trees in the lower layers, especially the bottom layer, is indispensable to maintain diversity in Okinawan evergreen broadleaf forests. Castanopsis sieboldii (Mak.) Hatusima had the highest importance value in all layers, indicating that it is typically a facultative shade species as well as a climax species. The spatial distribution patterns of trees were found to be random in the lower three layers, but in the top layer clumping seemed to occur at three spatial scales. A high degree of overlapping in spatial distributions of trees among the layers suggested that light cannot penetrate easily into the lower layers. As a result, most species in the lower layers must be shade-tolerant. Mean weight index decreased from the top toward the bottom layer, and tree density increased from the top downward. This trend resembled the mean weight-density trajectory of self-thinning plant populations

琉球列島産ウワバミソウ属4種の染色体数

[短報] Short communicatio

ミヤコジシバリ(キク科)を愛知県渥美半島で発見

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Double migration of the endangered Tricyrtis formosana (Liliaceae) in Japan

別経路で二度来訪していた絶滅危惧植物 --世界遺産地域における生物多様性の成立過程--. 京都大学プレスリリース. 2024-01-26.The Ryukyu Islands of Japan are a biodiversity hotspot due to geographical and historical factors. Tricyrtis formosana is a perennial herbaceous plant that commonly found in Taiwan. But only a few populations have been identified in a limited habitat on Iriomote Island, while populations of unknown origin occur near human settlements in an area on the main island of Okinawa. To better understand these populations of the phylogenetic uniqueness and intrinsic vulnerability, we conducted comparative analyses including (1) phylogeny and population structure with MIG-seq data, (2) photosynthesis-related traits of plants grown under common conditions and (3) transcriptome analysis to detect deleterious variations. Results revealed that T. formosana was split into two clades by the congeners and that Iriomote and Okinawa populations independently derived from ancestral Taiwanese populations in each clade. Photosynthetic efficiency was lowest in the Iriomote population, followed by Okinawa and Taiwan. Transcriptome analysis showed that the Iriomote population accumulated more deleterious variations, suggesting intrinsic vulnerability. These results indicate that each T. formosana population in Japan is phylogenetically unique and has been independently dispersed from Taiwan, and that the Iriomote population presents a high conservation difficulty with a unique photosynthesis-related characteristic and a larger amount of deleterious variations

日本，台湾およびフィリピンにおけるハママンネングサ(ベンケイソウ科) の分子系統解析を用いた分類学的再検討

We conducted molecular phylogenetic analyses of plants treated as Sedum alfredii or S. formosanum collected from Japan, Taiwan, and the Philippines (Batan Island) with other 19 Sedum species primarily in East Asia using the internal transcribed spacer region of nuclear DNA to reexamine the taxonomic status of S. formosanum. Our results indicate that 15 plants treated as S. alfredii or S. formosanum included a clade with two Taiwanese endemic species, but were not sister to S. alfredii from Guangdong, China. In conclusion, this study supports the taxonomic treatment of Hatusima (1975), Ohba (1984, 2001), and Tang and Huang (1993) of S. formosanum as a separate species from S. alfredii.日本，台湾およびフィリピンに分布が知られているハママンネングサの分類に関しては，中国を基準産地とする Sedum alfrediiとする見解 （Liu and Chung 1977; 島袋1997） とS. alfredii とは独立した S. formosanum とする見解 （初島1975; Ohba 1984, 2001; Tang and Huang 1993） の2つがある。本研究ではハママンネングサの分類見解を再検討するため，東アジアに産するマンネングサ属他種19種を含めた核 DNAの ITS 領域を用いた分子系統解析 （ベイズ法と最節約法） を行った。解析の結果，日本 （九州・琉球列島），台湾およびフィリピンから採集したハママンネングサは中国から採集したS. alfredii と同じクレードにはまとまらず，台湾に固有のマンネングサ属2種とクレードを形成した。以上の結果から，ハママンネングサをS. alfrediiから独立した S. formosanumとする見解 （ 初島1975; Ohba 1984, 2001; Tang and Huang 1993）が支持された

Canopy Multi-layering and Woody Species Diversity in a Subtropical Evergreen Broadleaf Forest in Okinawa Island, Japan

国際共同シンポジウム: International Joint Symposium: Tropical Island Ecosystems and Sustainable Development (Moorea, French Polynesia), DATE:December 2-7, 2006, PLACE: Moorea, French Polynesia, CO-SPONSORS: Centre de Recherches Insulaires et Observatoire de l’Environnement (CRIOBE) / Richard B. Gump South Pacific Research Station (University of California Berkeley) / 21st COE Program of University of the Ryukyu

First record of the mycoheterotrophic orchid Gastrodia fontinalis (Orchidaceae) from Takeshima Island, the Ryukyu Islands, Japan

We found Gastrodia fontinalis T. P. Lin in a bamboo forest from Takeshima Island, which is the northernmost island of the Ryukyu Islands in Japan. This species is apparently rare and was previously considered to be an endemic Taiwanese species. Because there are a few minor differences between the original description and our specimens collected in Takeshima Island, here we report Gastrodia fontinalis from Takeshima Island as the first record outside of Taiwan, with a description of the specimens from Takeshima Island