Plant Conservation in Japan
Tsukuba Botanical Garden, National Museum of Nature and Science
Japan is among the 34 biological hotspots characterized by both high endemism of vascular plants and extensive loss of natural vegetation. In order to reveal domestic hotspots in Japan, we constructed 3-D biodiversity maps for endemic plants and threatened plants, which are useful for education. Results indicate that 6 of top 8 hotspots for endemic species correspond with those for threatened species. The top hotspot for both is Chichijima island, the Bonins, a World Natural Heritage. To provide explicit data of Japan’s endemic plants, a book, ‘Endemic Plants of Japan’, was published in 2011, showing 2,595 endemic taxa (31.4%) including 2,438 taxa (37.5%) of vascular plants. Botanical gardens in Japan have 960 (58% for 50% of GSPC 2010 Target 8) of 1650 threatened species in ex situ conservation and continue to increase such threatened plants for GSPC 2020. Botanical gardens also contributed to propagation and restoration of threatened plants, which are displayed for education in botanical gardens. However, restoration to nature has stopped for a CR species endemic to the Bonins, because potential contamination of organisms. We also pay attention to conservation of heterotrophic plants, like orchids, which need symbiotic endofungi. Basic research has been conducted for the taxonomic redefinition and the evolution of threatened species. The East Asian Botanical Garden Network has commenced international collaboration on threatened plants in East Asia. One of tentative results is that most of the threatened plants are confined to single countries/regions, indicating that in most species, marginal populations are threatened, though they may have variations to potentially give rise to different species. Inconsistency in taxonomic definition of endemic or threatened species is also disclosed.