Sciadopitys verticillata | Threatened Conifers of the World (en-GB)

Sciadopityaceae

Sciadopitys verticillata (Thunb.) Siebold & Zucc.

A monotypic family whose sole species is restricted to Japan. Past logging and landuse changes have led to a fragmented population where most remaining stnads have less than 100 individuals

Distribution

Endemic to Japan: occurring on Honshu (Aichi, Fukushima, Hiroshima, Kyoto, Nagano, Nara, Okayama, Wakayama), Shikoku, Kyushu (Myazaki). It is most abundant on the island of Shikoku, on the Nara Peninsula and in the mountains NE of Nagoya (both in Honshu).

Habitat and Ecology

Locally common in mixed conifer-angiosperm forests, with Chamaecyparis obtusa, C. pisifera, Tsuga sieboldii, Abies firma, Pinus parviflora, and angiosperms such as Aesculus turbinata, Magnolia obovata, Acanthopanax spp., Cercidiphyllum japonicum, and Acer rufinerve. In dense forest usually only ferns, mosses and liverworts grow under the trees, but in some localities shade tolerant shrubs and small trees such as Ilex sugeroki and Skimmia japonica can thrive. Sciadopitys occurs as solitary trees as well as in small 'groves' or more or less pure stands, reflecting events of recruitment and subsequent successional stages in the forest. This conifer is most commonly found in rocky, cool and moist ravines and valleys in mountainous areas, at altitudes between 200 m and 1700 m above sea level.

Human Uses

The durable wood of this species is used for construction purposes and to a limited extent for boat building and certain kinds of furniture. The fibrous bark was formerly used for caulking boats (oakum). Its most valuable commercial use is undoubtedly in the horticultural industry, as it is a popular planted tree in Japan and (more limited) in Europe and the USA. Apparently it was not introduced in China, as were a few other Japanese conifers such as Cryptomeria japonica. The Dutch, who were the only Europeans allowed to trade with Japan, brought it to Java early in the nineteenth century; it arrived successfully in England and the Netherlands in 1861. A small number of cultivars with dwarfed growth, variegated foliage and/or pendulous branches has been developed but these are rarely planted. Some of these seem to scarcely differ from the species

Conservation Status

Global status and rationale

Near Threatened

Although having suffered a decline mainly in its outlying subpopulations, it is estimated that this has not exceeded 20% of the total population of mature trees. Its extent of occurrence is in excess of 20,000 km² but its area of occupancy could not be estimated for lack of data. It does not meet the criteria under A or B for a threatened category because it is still abundant in its main areas of distribution. If reduction continues into these areas it may in future become threatened. As such it is assessed as Near Threatened as it almost qualifies for a threatened category under criteria A2d+4d.

Global Threats

Being a component species in mixed conifer-angiosperm forests where Chamaecyparis obtusa is commonly the dominant species, past logging and subsequent conversion to managed or planted forest, or other land uses, has restricted the occurrence of Sciadopitys in many regions. Most of the remaining stands in Honshu are now only small remnant populations and larger stands in more or less undisturbed forest are confined to Shikoku and Kyushu (Katoh 1948).

References and further reading

Katsuki, T., Luscombe, D & Farjon, A. 2013. Sciadopitys verticillata. The IUCN Red List of Threatened Species 2013: e.T34111A2846623. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T34111A2846623.en. Downloaded on 13 July 2017
Worth, J., S. Sakaguchi, N. Tanaka, M. Yamasaki & Y. Isagi 2013. Northern richness and southern poverty: contrasting genetic footprints of glacial refugia in the relictual tree Sciadopitys verticillata (Coniferales: Sciadopityaceae). Biological Journal of the Linnaean Society 108:263-277.
Worth, J., M. Yokogawa & Y. Isagi 2014. Outcrossing rates and organelle inheritance estimated from two natural populations of the Japanese endemic conifer Sciadopitys verticillata. Journal of Plant Research 127:617-626.
Worth, J., M. Yokogawa, A. Perez-Figueroa, Y. Tsumura, N. Tomaru, J. Janes & Y. Isagi 2014. Conflict in outcomes for conservation based on population genetic diversity and genetic divergence approaches: a case study in the Japanese relictual conifer Sciadopitys verticillata (Sciadopityaceae). Conservation Genetics:DOI 10.1007/s10592-014-0615-y.
Yumoto, T. 2011. Historical Perspectives on the Relationships Between Humanity and Nature in Japan. S.-K. Hong, et al. (eds.), Landscape Ecology in Asian Cultures. Ecological Research Monographs, DOI 10.1007/978-4-431-87799-8_1 pp. 3-10