Pseudotsuga japonica (Shiras) Beissn.

Pinaceae

Endemic to south-western Japan where the main threat is deforestation in order to establishment commercial plantations

Associated Names:

toga-sawara, goyo-toga and sawara-toga

Distribution

Endemic to Japan in W Honshu (Chugoku District), Shikoku. [E. H. Wilson (1916) reported it as very rare in Kyushu, but its occurrence there has not been confirmed]

Habitat and Ecology

Pseudotsuga japonica occurs at elevations between 500 to 650m above sea-level on Shikoku. It is rare and scattered in sheltered valleys and steep ravines, growing on old volcanic rock. The climate is warm temperate, moist, with annual precipitation between 1000 and 2000mm. It is locally a (major) constituent of mixed conifer-broad-leaved forests, with Tsuga sieboldii usually as the dominant species. Other conifers are Abies firma, Chamaecyparis obtusa, Torreya nucifera and Cryptomeria japonica, broad-leaved trees are e.g. Quercus salicina, Q. sessilifolia, Cleyera japonica, and Illicium religiosum (small tree), common shrubs are Eurya japonica, Pieris japonica, Rhododendron serpyllifolium, and Thea japonica. As in China, in Japan the genus, represented by a single species, is a minor constituent of mixed forests

Human Uses

It is of minor importance as a timber tree due to its rarity and modest size, although veteran trees can attain substantial trunk diameters. The wood is used for construction of traditional buildings and gateways and for furniture. In Japan, it may be seen planted in some parks and traditional gardens, outside its country of origin it is a rare tree only present in some arboreta. This species was collected by E.H. Wilson in 1914 and introduced via the Arnold Arboretum of Harvard University to the USA. In Europe it seems to have arrived a few years earlier, perhaps a little after 1900 in Germany. It grows slowly in cultivation and seems to remain a small tree with a rather limited life span.

Conservation Status

Global status

Endangered C2a(i)

Global rationale

This is a very rare species, with only small and scattered subpopulations of very slow growing trees. The total population is not larger than 2500 trees, there are no subpopulations exceeding 250 mature trees and there is a continuing decline.

Global threats

The main threat has been the conversion of habitat to plantation forestry and other uses. Regeneration is poor and older trees are declining. The total population of this species in Japan is estimated to be ca. 2000 mature trees and is considered to be continuously declining.

Conservation Actions

The species is known from the Mount Odaigahara & Mount Omine Biosphere Reserve on the island of Honshu