Shorea

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Shorea
Shorea roxburghii
Shorea roxburghii
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Malvales
Family: Dipterocarpaceae
Subfamily: Dipterocarpoideae
Genus: Shorea
Sections

See Shorea classification for complete taxonomy to species level.

Shorea is a genus of about 196 species of mainly rainforest trees in the family Dipterocarpaceae. The genus is named after Sir John Shore, the Governor-General of the British East India Company, 1793-1798. They are native to southeast Asia, from Northern India to Malaysia, Indonesia and the Philippines. In west Malesia and the Philippines this genus dominates the skyline of the tropical forests. The tallest documented tropical angiosperm is a 88.3 m tall Shorea faguetiana in the Tawau Hills National Park, in Sabah on the island of Borneo[1]. Borneo is also the hotspot of Shorea diveristy with 138 species, of which 91 are endemic to the island[2].

Contents

[edit] Ecology

[edit] Reproductive Biology

The majority of Shorea species are general flowering species. General flowering is an event that occurs at irregular intervals of 3–10 yr, in which nearly all dipterocarp species together with species of other families come heavily into flower[3]. It is thought that general flowering evolved to satiate seed predators[4] and/or to facilitate pollinaton[3]. It appears that both of these explantions hold merit[5]. Flowering is thought to be triggered by droughts that occur during transition periods from La Niña to El Niño[6]. It is suggested that the magnitude of a flowering event is dependent on the timing of the droughts associated with the El Niño southern oscillation (ENSO) cycle, with the largest events occurring after an interval of several years with no flowering[6].

Shorea are insect pollinated and a variety of insects have been implicated, with species within the sections of Shorea sharing the same insect pollinators. Flowering within a section is sequential within one habitat and species association to prevent competition for pollinators[7].

[edit] Economic uses

Many economically important timber trees belong to Shorea. They are sold under various trade names including Meranti, Lauan (or Luan), Seraya, Balau, Bangkirai. The alluringly-named "Philippine Mahogany" sold in North America is not a mahogany at all, but actually a mixture of woods from the genus Shorea. Non-timber products from Shorea spp. include Dammar and Illepe. Dammar, the resin from Dipterocarps, is collected from a variety of species. It various in colour among the different taxonomic groups. Shorea wiesneri is listed in many website as an important source of dammar[8], however, this appears to be either a trade name or a synonym[9][10].

[edit] Conservation status

One hundred and forty eight species of Shorea are currently listed on the IUCN Redlist. The majority of which are listed as being critically endangered[11]. There are some concerns regarding the IUCN's listing of Dipterocarps, as the criteria used to assess the level of threat are based mainly on animal population characteristics. This is thought to overstate the threat assessment, when applied to long-lived habitat-specific organism such as tree[2]. Furthermore one species reportedly extinct, on the IUCN Red list, Shorea cuspidata is reported to be common in the Bako National Park and also present in the Lambir National Park[2]. Threat assessment for each species can be accessed via the Shorea species page.

Conservation Status of Shorea spp.
IUCN red list category Number of species
Extinct 1
Critically Endangered 102
Endangered 34
Vulnerable 3
Least concern 6
Data deficient 2
Not evaluated ~48

[edit] References

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  1. ^ Borneo. Eastern Native Tree Society. Retrieved on 2008-01-29.
  2. ^ a b c Ashton, P.S. Dipterocarpaceae. In Tree Flora of Sabah and Sarawak, Volume 5, 2004. Soepadmo, E., Saw, L.G. and Chung, R.C.K. eds. Government of Malaysia, Kuala Lumpur, Malaysia. ISBN 983-2181-59-3
  3. ^ a b Sakai, Shoko; Kuniyasu Momose, Takakazu Yumoto, Teruyoshi Nagamitsu, Hidetoshi Nagamasu, Abang A. Hamid and Tohru Nakashizuka (1999). "Plant reproductive phenology over four years including an episode of general flowering in a lowland dipterocarp forest,Sarawak, Malaysia". American Journal of Botany 86: 1414-1436. 
  4. ^ Curren, Lisa M.; M. Leighton (2000). "Vertebrate responses to spatiotemporal variation in seed production of mast-fruiting Dipterocarpaceae". Ecological Monographs 70 (1): 101–128. 
  5. ^ Maycock, Colin R.; Richard N. Thewlis, Jaboury Ghazoul, Reuben Nilus and David F.R.P Burslem (2005). "Reproduction of dipterocarps during low intensity masting events in a Bornean rain forest". Journal of Vegetation Science: 635–646. 
  6. ^ a b Sakai, Shoko; Rhett D. Harrison, Kuniyasu Momose, Koichiro Kuraji, Hidetoshi Nagamasu, Tetsuzo Yasunari, Lucy Chong and Tohru Nakashizuka (2006). "Irregular droughts trigger mass flowering in aseasonal tropical forests in asia". American Journal of Botany 93: 1134-1139. 
  7. ^ LaFrankie, James V. Jr.; H. T. Chan (Jun 1991). "Confirmation of Sequential Flowering in Shorea (Dipterocarpaceae)". Biotropica 23 (2): 200-203. doi:10.2307/2388308. 
  8. ^ Dammar. Encyclopædia Britannica. Retrieved on 2007-11-14.
  9. ^ Dipterocarpaceae Data Base - Taxonomic Information. Royal Botanical Gardens, Edinburgh. Retrieved on 2007-11-14.
  10. ^ Electronic Plant Information Centre. Royal Botanical Gardens, Kew. Retrieved on 2007-11-14.
  11. ^ >The IUCN Red list of Threatened Species - Shorea search results. IUCN Redlist. Retrieved on 2007-11-12.