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 tropicalangiosperm 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. Borneo is also the hotspot of Shorea diversity with 138 species, of which 91 are endemic to the island.
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. General flowering is thought to have evolved to satiate seed predators and/or to facilitate pollination. Both explanations apparently hold merit. Flowering is thought to be triggered by droughts that occur during transition periods from La Niña to El Niño. The magnitude of a flowering event is suggested to be dependent on the timing of the droughts associated with the El Niño southern oscillation cycle, with the largest events occurring after an interval of several years with no flowering. Shorea spp. 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.
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". 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; however, this appears to be either a trade name or a synonym. Borneo tallow nut oil is extracted from the egg-shaped, winged fruit of Shorea species.
Conservation status
Of the 148 species of Shorea currently listed on the IUCN Redlist, the most are listed as being critically endangered. 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. 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. The Shorea species page gives threat classifications.
