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Betula chichibuensis 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Plantae Tracheophyta Magnoliopsida Fagales Betulaceae

Scientific Name: Betula chichibuensis H.Hara
Common Name(s):
English Chichibu Birch

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(iii)+2ab(iii); D ver 3.1
Year Published: 2014
Date Assessed: 2014-08-01
Assessor(s): Shaw, K., Roy , S. & Wilson, B.
Reviewer(s): Oldfield, S. & Rivers, M.C.
Justification:
The species is very rare in the wild, and was reported to be reduced to 21 trees in the wild in 1993 (McAllister 1993). Although no recent survey data provide updated population information, it is unlikely that remaining population exceeds 50 mature individuals. It has no close living relatives anywhere else in the world and it is therefore probably of very ancient origin. 

This species is known only from a single location at Mt Kamo-san, near Tano-Gun, in Gumna prefecture. It has a very small extent of occurrence and area of occupancy, both below the thresholds for being considered Critically Endangered under criterion B. The small population and restricted distribution of B. chichibuensis make it susceptible to natural disasters or disease and it occurs at one threat-based location. The species is also self-incompatible, requiring two individuals to be close enough to cross-pollinate one another, making seed production uncertain in small subpopulations. Wild collected seed has also shown low viability. These factors potentially threaten the survival of this species. Deforestation and habitat degradation are also evident in the Chichibu District, presenting a threat to the survival of this species.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Endemic to Japan, this species is confined to the Chichibu area in the mountains of Central Honshu on Mt Kamo-san, near Tano-Gun, in Gunma prefecture. As restricted to Mt Kamo-san, the extent of occurrence and area of occupancy are therefore estimated to be under thresholds for being considered Critically Endangered.
Countries occurrence:
Native:
Japan (Honshu)
Additional data:
Estimated area of occupancy (AOO) - km2:1-9
Number of Locations:1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The species exists as small subpopulations and is very rare. Twenty-one known individuals were reported in 1993 (McAllister 1993). Although no recent survey data provide updated population information, it is unlikely that remaining population exceeds 50 mature individuals. It has no close living relatives anywhere else in the world and it is therefore probably of very ancient origin. Although the sprouting habit of this species enables individuals to be very long-lived, it is self-incompatible so the need for two individuals to survive close enough together to cross-pollinate one another could make the production of seed uncertain in small subpopulations. The very low viability (less than one percent) of the wild collected seed from Japan suggests little viable seed production in the wild and therefore a low chance of natural regeneration.
Current Population Trend:Unknown
Additional data:
Number of mature individuals:21
Population severely fragmented:Unknown

Habitat and Ecology [top]

Habitat and Ecology:Betula chichibuensis forms a multi-stemmed shrub or small tree to 10 m high. This species grows in limestone outcrops. Although young immature plants appear to be relatively shade tolerant, mature trees are very intolerant of shade. The species also appears to be fairly tolerant of wet soils and is relatively drought tolerant, at least once established. The bark is initially brown and flaky but later develops conspicuous raised horizontal lenticels. It has papery ovate leaves, glabrous and green on the upper surface with white hairs on the underside, deeply veined. This species is monoecious with catkin-like creamy yellow male and catkin-like red female inflorescences. The fruiting catkins bear tiny nutlet fruits. This species flowers from May to June. 

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: There is no use or trade information available for this species.

Threats [top]

Major Threat(s): The small population and restricted distribution of B. chichibuensis make it susceptible to natural disasters or disease. The species is also self-incompatible, requiring two individuals to be close enough to cross-pollinate one another, making seed production uncertain in small subpopulations. Wild collected seed has also shown low viability. These factors potentially threaten the survival of this species. Deforestation and habitat degradation are evident in the Chichibu District.

Conservation Actions [top]

Conservation Actions: This species has been cultivated and when several clones are grown close together in cultivation the seed viability is high. In 1986 seeds were collected from trees growing on Mount Kamo-san and sent to Ness Botanic Gardens, University of Liverpool, UK. Some of the seeds were sown and others retained in case of failure. Eight clones from the original seed are now in cultivation and have been distributed as rooted cuttings taken from the original seedlings or viable seed to arboreta and botanic gardens in Europe and North America. Seedlings from the original wild-collected seed showed considerable variability in habit characteristics and most have flowered and fruited freely. As this species is easily propagated by cuttings, it is possible for commercial reproduction to occur from a single plant, and for one, self-incompatible clone to dominate the cultivated market of this species in the future. Care should be taken to maintain genetic diversity of this species.Both in situ and ex situ conservation are recommended for this species. Further field survey is recommended to determine population number and propagation material should be collected from as many remaining individuals as possible. This species was listed as Rare in Japan in the 1997 IUCN Red List of Threatened Plants. It is assessed as Endangered in the Red List of Threatened Plants of Japan.

Citation: Shaw, K., Roy , S. & Wilson, B. 2014. Betula chichibuensis. The IUCN Red List of Threatened Species 2014: e.T194282A2309490. . Downloaded on 24 September 2018.
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