Species composition and species richness of the Persea thunbergii type lucidophyllous forest

Abstract

Species composition and species richness were studied in the Persea type lucidophyllous forests on their southern distributional limit in Kagoshima, Miyazaki and Kochi prefectures and their northern distributional limit in Niigata, Yamagata, Akita, Miyagi and Iwate prefectures. In total, 121 quadrates were investigated. The Persea type lucidophyllous forests were classified into the Fico superbae-Persetum thunbergii Miyawaki 1998, the Arisaemato ringentis-Persetum thunbergii Miyawaki et al. 1971 and the Polystico-Persetum thunbergii Suzuki et Wada 1949. The Fico superbae-Persetum thunbergii was characterized by the presence of Trachelospermum gracilipes var. liukiuense, Maesa tenera, Psychotria serpens and others, and was distributed on Yakushima Island and Tanegashima Island. The Arisaemato ringentis-Persetum thunbergii was characterized by the presence of Ophiopogon ohwii, Trachelospermum asiaticum var. intermedium and Rohdea japonica and the absence of the differential species of the Fico superbae-Persetum thunbergii, and was distributed on Kushima, Nichinan, Ashizuri and Muroto. The Polystico-Persetum thunbergii was characterized by the presence of Ardisia japonica, Ophiopogon planiscapus, Dryopteris erythrosora and Dryopteris lacera, and was distributed in the Tohoku region. These three associations were distributed along the coast. The mean number of lucidophyllous elements per quadrate (10010, which was indicative of species richness, in the Fico superbae-Persetum thunbergii, the Arisaemato ringentis-Persetum thunbergii and the Polystico-Persetum thunbergii was 21.4-36.1, 28.6-33.5 and 2.8-10.0, respectively. The lowest species richness of the Polystico-Persetum thunbergii was caused by the salt breeze and the low temperatures in the area where this association was distributed.