|Scientific Name:||Thuja sutchuenensis|
|Red List Category & Criteria:||Endangered A1cd ver 3.1|
|Assessor/s:||Yang, Y., Li, N., Christian, T. & Luscombe, D|
|Reviewer/s:||Thomas, P. & Farjon, A.|
Was listed as Extinct in the Wild (Oldfield et al. 1998) but was rediscovered in October 1999 by a regional team of botanists, not far from (or perhaps at) the locality where P.G. Farges had collected the only known specimens between 1892 and 1900. The team found individual trees growing scattered on cliffs and ridges of the deeply cleft mountain. There were no large trees, with most being small or even shrub-like because of their locations at higher altitudes and on exposed ridges. Seedlings are scarce. The more accessible trees have mostly been felled for use in home building and for making various household products. The species may also have gone through a genetic bottleneck and be facing problems of inbreeding depression. Following its rediscovery in 1999 it was re-assessed as Critically Endangered. Further surveys since that assessment have produced more information so that a new assessment is required.
Decline over the last three generations is estimated to be 80%. Its known area of occupancy is less than 100 km2 and there is no longer any evidence of continuing decline. The total population is estimated to be between 5,000 and 7,000 mature individuals. On the basis of this information, this species no longer meets the criteria for listing as Critically Endangered. However it does meet the criteria for listing as Endangered under A1 where the causes of the decline are understood, have ceased and are likely to be reversible. It is hoped that due to the rapid response by the Chinese authorities this species will be able to make a recovery over the coming years.
|Range Description:||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
Native:China (Chongqing, Hubei - Regionally Extinct, Shanxi - Regionally Extinct)
|Range Map:||Click here to open the map viewer and explore range.|
Approximately 5,000-7,000 mature individuals are extant within the Dabashan and Xuebaoshan Nature Reserves.
|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.|
Formerly this taxon was listed as the only conifer Extinct in the Wild (EW) by IUCN SSC (Farjon and Page 1999). In October 1999 it was rediscovered by a regional team of Chinese botanists, not far from (or perhaps even at) the locality where R.P. Farges had made his last collections almost 100 years previously (Xiang et al. 2002). It was subject to extremely intensive logging from the 1970s to the 1990s, and possibly until as late as the species’ rediscovery in 1999 and the remaining individuals are only those left in inaccessible places and/or of small stature. Inbreeding among the remaining individuals is potentially a problem which requires further investigation. Plant diseases caused by microorganisms have also been observed, but it is not clear what impact, if any, these may have.
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.
|Citation:||Yang, Y., Li, N., Christian, T. & Luscombe, D 2013. Thuja sutchuenensis. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 09 March 2014.|
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