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Status of Ex Situ Conservation of Threatened Japanese Plant Species in Japanese Botanic Gardens

Volume 3 Number 2 - July 2006

Tomohisa Yukawa

In the last six years, the Conservation of Endangered Plants Committee of the Japan Association of Botanical Gardens (JABG) and the Tsukuba Botanical Garden of the National Science Museum have undertaken two surveys on the Status of ex situ conservation of threatened plant species.  The first survey ascertained the work on threatened plant species by association members and was published by the Conservation of Endangered Plants Committee (2001).  In the second survey, detailed data concerning the threatened Japanese plant species held by each garden was collected and analyzed (Yukawa, 2004).  Some of the results, apart from sensitive information such as the habitat has been posted on the JABG website (2004).  This paper summarises the results of the second survey to illustrate the status of biodiversity conservation in Japanese botanic gardens.

Survey Procedure

Format for Japanese threatened plants databaseA copy of Red List Plant Edition (Environmental Agency, 1997) was sent to the JABG members for them to indicate if they held any of the 1536 taxa listed as extinct, threatened or semi–threatened.  The data for each taxon was entered on an MS Excel spreadsheet (Table 1).  The fields are similar to BG Plants, the database of cultivated plants for research purposes which has been developed by university botanic gardens.  Since the start of the survey, the Environmental Agency published a revised Red List (2000).  This Red List with 1835 threatened taxa was used in the analysis of the data.  However, it is to be expected that due to the timing of the survey some target species might not be listed.


A response was received from 87 of the 137 member gardens (approximately 64%).  Of these, 30 gardens (approximately 22%) responded “no relevant plant species”.  There was a swift response from gardens that have developed their own databases which indicates that a database is thought to be an important facility for managing living collections.  As this was a complicated survey the response rate is considered fairly good.  However, as there was no response from 50 gardens and 30 gardens had no relevant species indicates that there are many gardens that grappling with the problem of conserving biodiversity.


Click to view the figure at full sizeThe results are shown in Figure 1.  The total number of threatened plants in ex situ conservation was 3730.  This comprised 695 taxa (approximately 38% of the 1835 target taxa from the Red Data Book Vascular Plant Edition) (Figure 1a).  459 taxa (66%) had three accessions or less (Figure 1b) and 30% (1103) accessions were of wild origin (Figure 1c).

It is likely that the total of 695 threatened plant taxa held in association gardens is lower than the true figure as this was a complicated survey and the earlier Red List was used.  However, it is clear that the conservation status of threatened plant species in Japanese botanic gardens is grave.  Further the diversity within species is low and there is only original habitat date for 30% of the accessions.


It is proposed that all Japanese botanic gardens should aim to conserve all Japanese plant species as either living plants, seeds or spores, however, the first priority is the conservation of threatened taxa.  The list of those taxa which are in ex situ conservation in members gardens is posted on the JABG website and will provide the baseline for Japanese botanic gardens as they make progress towards the ex situ conservation of threatened Japanese taxa.  The Association members can obtain more detailed information through the executive office of the JABG..  The results of this survey will be used for the development of activities of the JABG and every garden.


I wish to express my deep gratitude to the members of the JABG who cooperated with this survey especially the Conservation of Endangered Plants Committee.  Part of the expenses for this research were covered by a scientific research grant (subject 15201050) from the Ministry of Education, Culture, Sports, Science and Technology and the National Science Museum.


Environmental Agency, 1997.  Red Data List Plant Edition. Environmental Agency, Tokyo
Environmental Agency, 2000, Revision, Japanese Threatened Species – Red Data Book – 8 Plants I (vascular plants), Natural Environment Research Centre, Tokyo.
Japan Association of Botanical Gardens, 2004. Status of ex situ conservation of threatened Japanese plant species in Japanese botanic gardens accessed 5 May 2006
Threatened Plant Species Committee, 2001. Conservation Status of Threatened Plant Species Survey (former survey) questionnaire results. Japan Association of Botanical Gardens Magazine 35: 159-166.
Yukawa, T., 2004. Conservation Status of Threatened Japanese Indigenous Plant Species in Japanese Botanical Gardens and Future Initiatives. Japan Association of Botanical Gardens Magazine 38: 39-44.

About the Author 

Tomohisa Yukawa is at the Tsukuba Botanical Garden of the National Science Museum