Shorea
Temporal range: Early Eocene–present
Shorea roxburghii.jpg
Shorea roxburghii
Scientific classification e
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malvales
Family: Dipterocarpaceae
Subfamily: Dipterocarpoideae
Genus: Shorea
Roxb. ex C.F.Gaertn.
Sections

See List of Shorea species for complete taxonomy to species level.

Synonyms
  • Anthoshorea
    Pierre
  • Caryolobis
    Gaertn.
  • Doona
    Thwaites
  • Isoptera
    Scheff. ex Burck
  • Pachychlamys
    Dyer ex Ridley
  • Parahopea
    F.Heim
  • Pentacme
    A.DC.
  • Richetia
    F.Heim
  • Saul
    Roxb. ex Wight & Arn.

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. The timber of trees of the genus is sold under the common names lauan, luan, lawaan, meranti, seraya, balau, bangkirai, and Philippine mahogany.[1]

Taxonomy

Shorea fossils (linked with the modern sal, S. robusta, which is still a dominant tree species in Indian forests) are known from as early as the Eocene of Gujarat, India. They are identifiable by the amber fossils formed by their dammar resin.[2] Other fossils include a Miocene-aged fossilized fruit from the same region; this fruit most closely resembles the extant S. macroptera of the Malay Peninsula.[3]

Description

Shorea spp. 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 an 88.3-m-tall Shorea faguetiana in the Tawau Hills National Park, in Sabah on the island of Borneo, and in that park at least five other species of the genus have been measured to be over 80 m tall: S. argentifolia, S. gibbosa, S. johorensis, S. smithiana, and S. superba.[4] Borneo is also the hotspot of Shorea diversity with 138 species, of which 91 are endemic to the island.[5]

Species

Main article: List of Shorea species

Reproductive biology

The majority of Shorea spp. are general flowering species, which is an event that occurs at irregular intervals of 3–10 yr, in which nearly all dipterocarp species together with species of other families bloom heavily.[6] General flowering is thought to have evolved to satiate seed predators[7] and/or to facilitate pollination.[6] Both explanations apparently hold merit.[8] Flowering is thought to be triggered by droughts that occur during transition periods from La Niña to El Niño.[9] The magnitude of a flowering event is suggested to be 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.[9]

Shorea spp. are insect pollinated. A variety of insects have been identified as pollinators, 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.[10]

Seed predation and mortality have an impact on the reproduction process of dipterocarps such as Shorea. In Singapore, crab-eating macaque and moth larvae are known seed predators.[11]

Uses

Many economically important timber trees belong to Shorea. They are sold under various trade names including "lauan", "lawaan", "meranti", "seraya", "balau", "bangkirai", and "Philippine mahogany". (For a list of species associated with each name, see the article on Dipterocarp timber classification.) The "Philippine mahogany" sold in North America is not a true mahogany at all, but a mixture of woods from the genus Shorea.

Other products from Shorea spp. include dammar and illepe. Dammar is a resin collected from a variety of species. It varies in colour among the different taxonomic groups. Shorea wiesneri is listed in many websites as an important source of dammar;[12] however, this appears to be either a trade name or a synonym.[13][14]

Borneo tallow nut oil is extracted from the egg-shaped, winged fruit of Shorea species.[15]

Conservation status

Of the 148 species of Shorea currently listed on the IUCN Redlist, most are listed as being critically endangered.[16] Some concerns exist 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 organisms such as trees.[5] The Shorea species page gives threat classifications.

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

See also

References

  1. ^ Lauan - The Wood Database
  2. ^ Sahni, A.; Patnaik, R. (2022-06-01). "An Eocene Greenhouse Forested India: Were Biotic Radiations Triggered by Early Palaeogene Thermal Events?". Journal of the Geological Society of India. 98 (6): 753–759. doi:10.1007/s12594-022-2064-4. ISSN 0974-6889. S2CID 249536528.
  3. ^ SHUKLA, ANUMEHA; GULERIA, J. S.; MEHROTRA, R. C. (2012-02-01). "A fruit wing of Shorea Roxb. from the Early Miocene sediments of Kachchh, Gujarat and its bearing on palaeoclimatic interpretation". Journal of Earth System Science. 121 (1): 195–201. doi:10.1007/s12040-012-0142-5. ISSN 0973-774X.
  4. ^ "Borneo". Eastern Native Tree Society. Retrieved 2008-06-21.
  5. ^ a b 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
  6. ^ a b Sakai, Shoko; K Momose; T Yumoto; T Nagamitsu; H Nagamasu; A A Hamid; T 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 (10): 1414–36. doi:10.2307/2656924. JSTOR 2656924. PMID 10523283. Retrieved 2007-11-13.
  7. ^ Curran, Lisa M.; M. Leighton (2000). "Vertebrate responses to spatiotemporal variation in seed production of mast-fruiting Dipterocarpaceae". Ecological Monographs. 70 (1): 101–128. doi:10.1890/0012-9615(2000)070[0101:VRTSVI]2.0.CO;2. hdl:2027.42/116363.
  8. ^ Maycock, Colin R.; R. N. Thewlis; J. Ghazoul; R. Nilus; David F. R. P. Burslem (2005). "Reproduction of dipterocarps during low intensity masting events in a Bornean rain forest". Journal of Vegetation Science. 16 (6): 635–46. doi:10.1658/1100-9233(2005)016[0635:RODDLI]2.0.CO;2.
  9. ^ a b Sakai, Shoko; Rhett D. Harrison; Kuniyasu Momose; Koichiro Kuraji; Hidetoshi Nagamasu; Tetsuzo Yasunari; Lucy Chong; Tohru Nakashizuka (2006). "Irregular droughts trigger mass flowering in aseasonal tropical forests in Asia". American Journal of Botany. 93 (8): 1134–39. doi:10.3732/ajb.93.8.1134. PMID 21642179. Retrieved 2007-11-13.
  10. ^ LaFrankie, James V. Jr.; H. T. Chan (June 1991). "Confirmation of Sequential Flowering in Shorea (Dipterocarpaceae)". Biotropica. 23 (2): 200–203. doi:10.2307/2388308. JSTOR 2388308.
  11. ^ Chong, Kwek Yan; Chong, Rie; Tan, Lorraine W.A.; Yee, Alex T.K.; Chua, Marcus A.H.; Wong, Khoon Meng; Tan, Hugh T.W. (1 November 2016). "Seed production and survival of four dipterocarp species in degraded forests in Singapore". Plant Ecology & Diversity. 9 (5–6): 483–490. doi:10.1080/17550874.2016.1266404. S2CID 89849984.
  12. ^ "Dammar". Encyclopædia Britannica. Retrieved 2007-11-14.
  13. ^ "Dipterocarpaceae Data Base—Taxonomic Information". Royal Botanical Gardens, Edinburgh. Retrieved 2007-11-14.
  14. ^ "Electronic Plant Information Centre". Royal Botanical Gardens, Kew. Retrieved 2007-11-14.
  15. ^ "Minor oil crops - Individual monographs (Balanites-Borneo tallow nut-Brazil nut-Caryocar spp)". www.fao.org. FAO. Retrieved 15 April 2017.
  16. ^ "IUCN Red List of Threatened Species, Shorea search results". IUCN. 2012. Retrieved 3 January 2013.