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Tsuga dumosa

Tsuga dumosa - Himalayan hemlock
  • Tsuga dumosa - Himalayan hemlock  - Click to enlarge
  • Tsuga dumosa leaves - Click to enlarge
  • Tsuga dumosa trees - Click to enlarge

 

Scientific name: Tsuga dumosa  (D. Don) Eichler  1887

Synonyms: Abies brunoniana Griff., Abies brunoniana Lindl., Abies cedroides Griff. ex. Carrière, Abies decidua Wall. ex. K.Koch, Abies dumosa (D.Don) Mirb., Abies dumosa Loudon, Abies yunnanensis Franch., Micropeuce brunoniana Carrière, Picea brunoniana Spach ex. Gordon, Pinus brunoniana Wall., Pinus decidua Wall. ex. Carrière, Pinus dumosa D.Don, Tsuga brunoniana (Wall.) Carrière, Tsuga calcarea Downie, Tsuga chinensis subsp. wardii (Downie) A.E.Murray, Tsuga dumosa subsp. leptophylla (Hand.-Mazz.) A.E.Murray, Tsuga dumosa subsp. yunnanensis (Franch.) Silba, Tsuga dumosa var. yunnanensis (Franch.) Silba, Tsuga dura Downie, Tsuga intermedia Hand.-Mazz., Tsuga leptophylla Hand.-Mazz., Tsuga wardii Downie, Tsuga yunnanensis (Franch.) E.Pritz., Tsuga yunnanensis (Franch.) Mast., Tsuga yunnanensis subsp. dura (Downie) A.E.Murray

Common names: Himalayan hemlock (English), Yunnan tieshan (Chinese), Sula, Thingia (Nepali)

 

Description

Tree to 35(-50) m tall, with straight or early forked trunk to 2.7 m in diameter. Bark furrowed, scaly, pinkish brown to gray-brown. Crown broadly conical, flattening with age. Twigs thinly hairy. Winter buds blunt, 2-2.5 mm long. Needles variable in length, 1-2.5(-3.5) cm long, tapering from the base to the pointed tip, with tiny teeth along the edge, the white stomatal bands each with 8-10 lines of stomates. Pollen cones 2.5-5 mm long, yellow. Seed cones green before maturity, ripening light brown, (1.3-)1.8-2.5(-3) cm long, opening to 1.5-2.5(-3) cm wide, the seed scales 10-14 mm long. Seed body 3.5-4.5 mm long, the wing 3.5-4.5 mm longer.

The species name, meaning “bushy” is not terribly appropriate for a large tree but refers to the tendency of the trunk to fork near the base.

Himalaya, from northern Uttar Pradesh (India) to southwestern Sichuan (China) and northern Myanmar. Moist to wet slopes in the monsoon region; (1,700-)2,400-3,000(-3,500) m.

 

Conservation Status

Red List Category & Criteria: Least Concern

A widespread and very common species, which although exploited in places, is not undergone a significant decline and is hence listed as Least Concern.

It is a very widespread and abundant species. It is only scarce in the Vietnamese part of its range and also in part of the Chinese range. The size of the population of Tsuga dumosa in Vietnam is unknown, at each of the localities where it has been found, it is probable that this species also occurs on surrounding ridges and peaks but it does not appear to be as frequent as Pseudotsuga. The majority of the known populations have been subject illegal logging and there are few mature trees remaining in these localities. Some sites show recent regeneration but as so little is known about its regenerative capacity, it is uncertain if the young trees will survive to maturity. At a national level, the Vietnamese populations probably meet the criteria for Vulnerable. Further field work may result in an upgrading to the category of endangered. The Vietnamese populations may also be important as they represent the most southern distribution of this genus in Asia, they may be a distinct genetic provenance.

Tsuga dumosa occurs in the Himalaya in a belt between 2,600 m and 3,200 m a.s.l., in a wide range of habitats, usually on alpine lithosols. In China it is most common between 2,200 m and 2,800 m a.s.l., but it occurs as low as 1,700 m and up to 3,500 m a.s.l. in Sichuan and Yunnan. The climate is moist monsoon, with abundant precipitation, wettest in the eastern Himalayas and Upper Burma, where it can receive up to 10,000 mm rain per year. It is an almost constant companion of conifers, e.g. Abies spp., Picea spp.; Cedrus deodara in the western Himalayas, and Larix griffithii in the eastern Himalayas; it is especially abundant on slopes with a northerly exposure, where it is the most shade tolerant tree.

Himalayan Hemlock is a timber tree of some importance locally, but considered by Indian foresters to be inferior to several other Himalayan conifers. Its wood can be split into shingles and together with the bark these are traditionally used in the roofing of wooden houses. The foliage is sometimes burnt as incense in Buddhist religious shrines. This species has been introduced in Europe (England) in 1838, but is not common in cultivation; sometimes trees are listed under its synonym Tsuga yunnanensis when coming from the Chinese part of its range. Its planting is usually limited to arboreta and botanic gardens with living collections of conifers in regions with mild winters and abundant rainfall.

In Vietnam this species is known to occur in Hoang Lien National Park, and it probably occurs in many other protected areas across its extensive distribution range.

 

Cultivars: -

 

References

  • Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
  • Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
  • IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.


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