Phytosociological study of a Suaeda malacosperma community and distribution of Suaeda species in western Kyushu.

Abstract

The phytosociology of a Suaeda malacosperma community in Japan and distribution of four species belonging to the genera Suaeda (Chenopodiaceae) ; S. asparagoides (Miq.) Makino, S. maritima (L.) Dumort, 5. japonica Makino and S. malacosperma Hara in western Kyushu, were studied. These species predominantly grow on salt marsh, except S. asparagoides which grows at the high tide line on sandy or shingly beach. In western Kyushu, S. asparagoides was chiefly found on islands, and was mostly frequent in the northern island of Tsushima. S. maritima was widely distributed, but S. japonica was restricted to Ariake Bay area. S. malacosperma was distributed in Tsushima, Kami-goto and Sasebo City in Nagasaki Prefecture and Ariake Bay area in Saga Prefecture. S. japonica and S. malacosperma were found together at some localities in Ariake Bay area and S. maritima and S. malcosperma were found together at a locality in Tsushima and Kami-goto. However, S. maritima and S. japonica were never found at the same locality. S. malacosprma was an endemic species distributed from Aichi Prefecture through the Seto Inland Sea area to western Kyushu. The range extended in a restricted area from north to south, and widely from east to west. The easternmost locality was in Atsumi Peninsula of Aichi Prefecture and the westernmost locality was in Wakamatsu-cho of Nagasaki Prefecture. Plants of this species already became extinct in Okayama, Fukuoka, Kumamoto and Kagoshima Prefectures, and is endangered in other prefectures. S. malacosperma community syntaxonomically classified as a new association Suaedetum malacospermae with three subassociations.