Notes on naturalized plants in Hiroshima Prefecture, SW Japan: 8. An alien tree Triadica sebifera (Euphorbiaceae) newly confirmed on Miyajima Island

Abstract

An alien species, Chinese tallow tree, Triadica sebifera (L.) Small [Euphorbiaceae] is newly confirmed on Miyajima (Itsukushima) Island, Hiroshima Prefecture, south-western Japan, where it has been found near low human impacted evergreen forests in a world heritage listed site. This plant was introduced into Japan for gardening and for its use as a street tree and has become naturalized as an alien species in Japan. The species was first collected in Hiroshima Pref., from Minami-ku, Hiroshima City by K. Yamada on 7 October 1956 and from Miyajima Island by H. Kubo on 16 October 2013. It has adversely impacted the forest ecosystem because it is growing rapidly and forming a mono community. T. sebifera is listed in the top 100 of the world's worst invasive alien species. Here we present the growing conditions in Miyajima Island and discuss the potential effect of this deer-unpalatable species on forest regeneration. The species occurs in areas where sika deer Cervus nippon forage and which also affect the integrity of the forest vegetation. We are now planning an eradication action program for the species in collaboration with the local administration and the Ministry of Environment of Japan.