Definitions

Shorea

Shorea

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, and in that park at least 5 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. Borneo is also the hotspot of Shorea diversity with 138 species, of which 91 are endemic to the island.

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. It is thought that general flowering evolved to satiate seed predators and/or to facilitate pollinaton. It appears that both of these explanations hold merit. Flowering is thought to be triggered by droughts that occur during transition periods from La Niña to El Niño. 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.

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.

Economic uses

Many economically important timber trees belong to Shorea. They are sold under various trade names including "Meranti", "Lauan" (or "Luan"), "Seraya", "Balau", and "Bangkirai". (For a list of species associated with each name, see the article on Dipterocarp timber classification.) 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, however, this appears to be either a trade name or a synonym.

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. 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. 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. 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

References

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