Cupressus torulosa var. gigantea
|Scientific Name:||Cupressus torulosa D.Don var. gigantea (W.C.Cheng & L.K.Fu) Farjon|
Cupressus gigantea W.C.Cheng & L.K.Fu
|Taxonomic Source(s):||Farjon, A. 2010. A Handbook of the World's Conifers. Koninklijke Brill, Leiden.|
|Taxonomic Notes:||Cupressus gigantea was briefly described by Cheng and Fu (1975) based on two collections at PE made earlier (1934 and 1972) in E Xizang (Tibet). Another earlier collection, not known to the Chinese authors, belongs here: Ludlow, Sherriff and Elliott 13345; it was determined as C. torulosa. That taxon does also occur in the Zangbo Valley (e.g. Ludlow, Sherriff and Elliott 12141), but C. gigantea is more common. The morphological differences between both species are small; C. gigantea has thicker (1.5-2 mm) ultimate branchlets with closely appressed, rhombic-gibbous leaves. Tree size is a very doubtful taxonomic character and pollen and seed cones of both taxa are similar. It is possible that C. gigantea is merely a xeromorphic variant of C. torulosa; a collection of C. torulosa from the W Himalaya (Gamble 23119) has ultimate branchlets equally thick as Xizang Medical Plants Exped. 4314, the paratype of C. gigantea. On the other hand both forms appear to occur in the same general area of the Zangbo Valley, though not strictly sympatric. Recently, several collections have been made which appear to demonstrate that within populations and even individuals of C. gigantea the thickness of ultimate branchlets can vary (G. Miehe et al. 97-08001 (K!), B. Dickoré 10503, 10561 (K!)) with slender branchlets present in some trees. Field studies, backed up by a genetic analysis, may be necessary to determine the status of this taxon more confidently than is possible on the basis of herbarium collections only. It is on the basis of current evidence here considered better to recognize it as a variety of C. torulosa.|
|Red List Category & Criteria:||Vulnerable A2cd ver 3.1|
|Assessor(s):||Zhang, D, Qin, H.-n., Christian, T. & Rushforth, K.|
|Reviewer(s):||Thomas, P. & Farjon, A.|
The historic loss of up to 50% of mature individuals in the last three generations (60 to 115 years) places this taxon in the Vulnerable category under criterion A.
|Previously published Red List assessments:|
|Range Description:||This species is found in China: south Xizang [Tibet] (Zangbo River Valley, from ca. 93° to ca. 96° E); and possibly extreme northwest Yunnan (vicinity of Dêqên on the Langcang [Mekong] River), based on a specimen collected in 1992.|
Native:China (Tibet [or Xizang])
|Range Map:||Click here to open the map viewer and explore range.|
Wang et al. (2010) surveyed 13 quadrants within the area 28 59’ 22” to 28 59’ 49” N and 93 16’ 52” – 93 18’ 57” E (3120 m to 3210 m a.s.l.) each covering an area of 1 km2 which between them contained ca 366 mature individuals. Regeneration throughout this area was poor.
In one location, near Linzhi, an estimated 300-500 mature individuals were directly observed in 2007 but with no regeneration.
The variety is common along the Yarlung Tsangpo valley from Nang for about 30-40 km with more scattered trees at higher elevations along the same stretch. An estimated 2000 mature individuals occur in this area, and “copious regeneration” has been observed. (Direct observations by Keith Rushforth, 1995-1999).
It is estimated that the number of mature individuals throughout the range do not total more than 5000 trees.
Since 1998 the extant population of mature individuals is believed to have stabilized.
|Current Population Trend:||Stable|
|Habitat and Ecology:||This species is found in scattered stands or groves, with few other large shrubs, surrounded by open dry scrubland; usually on east-facing slopes, often seasonally grazed. It occurs in sandy or stony fluvio-glacial sediments or on slopes over limestone. The climate is seasonal (east monsoon, dry winds from the Tibetan Plateau in the west), with cold winters and with an annual precipitation of less than 500 mm; rainfall is from June-September.|
|Generation Length (years):||20-35|
|Use and Trade:||Timber and firewood are locally taken. Large trees are often venerated in local traditions and religion.|
Due to the scarcity of timber in the region where scattered groves of var. gigantea occur, there is continuous pressure for exploitation. Regeneration is often poor due to grazing of livestock. Extensive logging (estimated at around 50% of mature individuals) took place between the 1960s and 1980s. Wang et al. (2010) found regeneration to be poor throughout their entire study area, and further direct observations support this for the area around Linzhi. A decline in the quality of habitat around Linzhi has been observed, and is a result of deforestation and subsequent soil erosion.
Several groves are protected as 'sacred forest' by Buddhist monks and some of the largest trees are on grounds used as a cemetery, where any cutting is prohibited. Other locations have also been designated as a National Park and protected by local government. The taxon is cultivated in botanic gardens both within China and in the UK where conservation collections of known wild origin are maintained.
|Citation:||Zhang, D, Qin, H.-n., Christian, T. & Rushforth, K. 2013. Cupressus torulosa var. gigantea. The IUCN Red List of Threatened Species 2013: e.T32336A2815433.Downloaded on 22 November 2017.|
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