Conservation of the endemic vascular plant species of the Bonin (Ogasawara) Islands

Abstract

The Bonin Islands, consisting of about 20 small islands, are located in the western Pacific Ocean about 1000 km south of the Japanese mainland. The flora of the Bonin Islands is characterized by a high proportion of endemism: 30.4% of indigenous angiosperms, or c. 43% of trees and shrubs. Although humans have inhabited the Bonin Islands for less than 200 years, their impact on the flora has been substantial. Because each island is so small and the diversity of available habitats low, plant species have few options for survival. In addition to the negative effects of human impact, climatic disasters such as droughts or typhoons have exerted considerable damage on certain species. After World War II, the Bonin Islands were left almost uninhabited during more than 20 years of military occupation. During this period many crops and cultivated species escaped and outcompeted original vegetation. Feral goats also contributed to the damage. Of the approximately 460 taxa of flowering plants now found native to the Bonin Islands (including c. 140 endemic taxa), about 80 taxa are considered endangered. Recent efforts toward conservation of selected endangered endemic taxa are discussed.