Thuja sutchuenensis Franchet

Cupressaceae

Represented by a single population in Southwest China where up until 1990 it was thought to be extinct; mainly as a result of  selective logging.

Associated Names:

Distribution

Endemic to China, occurring in Chongqing (formerly part of Sichuan Province; now administered directly from Beijing): Chengjou County, Kaixian County.

In 1892, the French missionary P.G. Farges was the first westerner to conduct a botanical survey in Chengkou county, Chongqing Municipality (formerly eastern Sichuan Province), in central China. Among the many new species discovered by Farges, was Thuja sutchuenensis. After his first collection, Farges returned a number of times to the area up until 1900 and collected additional specimens of this species. Later in the twentieth century, a number of botanical collecting trips were made to Chengkou by Chinese botanists. Some trips were specifically made to find T. sutchuenensis. However, nothing was found and it therefore remained known only from specimens collected by Farges and lodged in various European herbaria, although it was said to be in cultivation in China. Nothing was known about the habitat in which the species had been found, and it was not even certain that the species had been collected in the wild, as only the town of Chengkou was mentioned as its locality. As a result, the species was widely regarded to be Extinct in the Wild, and was considered to be the only conifer to have disappeared from nature in historic times (Farjon and Page 1999).

In October 1999, an expedition in search of rare and endangered plants of Chongqing Municipality organized by a local forest bureau carried out a thorough investigation of Chenkou county. In the Dabashan Mountains they discovered a wild population of Thuja sutchuenensis. Extensive searches since the species’ rediscovery in 1999 have failed to find any extant plants in Shanxi or Hubei provinces within the species’ supposed historic range

Habitat and Ecology

This very restricted species occupies steep slopes and ridges of limestone mountain sides between 800 m and 2,100 m a.s.l. in mixed angiosperm shrubland and forest. The soil is mountain yellow-brown earth developed from limestone, rich in organic matter (2.3-3%) and with a thick humus layer (ca. 20 cm) and a pH of 6.2-7. The climate is warm temperate and humid with mean annual precipitation ca. 1,400 mm. Other associated conifers are Tsuga chinensis, Cephalotaxus fortunei, Torreya fargesii, Pinus armandii and P. cf. henryi; angiosperm trees include species in the genera Quercus, Carpinus, Fraxinus, Trachycarpus, Juglans, Dendropanax, Cinnamomum, Broussonetia, Cotinus, Cycobalanopsis, Fagus and many more, most are deciduous.

Human Uses

The wood of this species is soft, light, easily worked and durable. It is used for applications requiring decay resistance by local people, e.g. home construction, production of shingles, application for funeral services, etc. It is too rare to possess much commercial value. The species is in cultivation at Wuhan Botanic Garden, China. It is not believed to be in cultivation outside China.

Conservation Status

Global status

Endangered A1cd

Information for this species will be completed shortly

Conservation Actions

Distributed within the boundaries of two nature reserves: the Dabashan Nature Reserve and the Xuebaoshan Nature Reserve. In the Dabashan Nature Reserve, the authorities have relocated the local population to aid the conservation of the species. In order to achieve better protection, work involving local stakeholders is being carried out with help from Bedgebury National Pinetum (UK Forestry Commission) in Kent, England. Ex situ conservation is being undertaken at Wuhan Botanic Garden