2024 Volume 106 Issue 4 Pages 109-115
The Oki Islands in the Sea of Japan were connected to the Shimane Peninsula during the glacial period. The vertical distribution of forest vegetation is unclear and glacial relict tree species might exist. To clarify the characteristics of the tree species composition of the Oki Islands, we compared the tree species compositions of the Oki Islands with those of the Tsushima Islands, which were connected to Kyushu and the Korean Peninsula in the Middle Pleistocene, and Sado Island, which has been a remote island since the Middle Pleistocene. We identified 272 taxa on the Oki Islands, 329 on the Tsushima Islands, and 313 on Sado Island. The Oki Islands are characterized by the smallest area and the fewest tree taxa. The Tsushima Islands, located in the south, had more continental and southern taxa, while Sado Island, located in the north, had more northern taxa. The Oki Islands, located in between, had many taxa in common with both islands and the taller trees of deciduous oaks and evergreen Lauraceae.
