Native to Indonesia and Malaysia where it is threatened due to logging for its highly prized wood.
bulok, tubu and tumuh
A Bornean species recorded from Indonesia (Kalimantan Timur) and Malaysia (Sabah, Sarawak) where it is known from seven localities. In addition to those mapped in Flora Malesiana (de Laubenfels, 1988) there are two in Kalimantan Timur. Of the three dots on the map in that publication for central Sarawak, only one could be confirmed with a herbarium collection: Julan ["Usan Apau"] coll. G.H. Pickles 3929 at Leiden (det. D.J. de Laubenfels).
Logging has had a negative impact on the number of mature individuals because it occurs at a rate well beyond natural regrowth. Uncut stands are still being targeted where not inside a protected area.
Habitat and Ecology
Agathis orbicula occurs at lower altitudes than A. lenticula in evergreen tropical rainforest and high kerangas. Recorded from 450 up to 1,050 m a.s.l.
Agathis orbicula is a timber tree producing valuable wood. Loggers rarely if ever distinguish this species from other Agathis species (e.g. A. borneensis) that occur in the same general area.
Logging of Agathis in Borneo involves all species of lowland to lower montane forest habitats. Of the seven localities (dots on the map) documented by herbarium collections of A. orbicula, only two appear to be within protected areas. From these circumstances a continuing decline of mature trees in the population is inferred. Based on calculations using the herbarium-based localities the area of occupancy (AOO) on a 5km wide grid (IUCN recommendation is 2 km) is 175km² which is well below the threshold of 500km² for Endangered. The previous IUCN assessment (1998) arrived at Vulnerable because a higher threshold for the AOO was used due to uncertainty about the distribution of the species. The distribution remains poorly known and can only become known better if more herbarium specimens that include mature pollen cones (for determination) are made and sent to institutional herbaria. Field determination is possible, but requires awareness of the distinctive characters.
Exploitation of all tall trees of Agathis in Borneo has been intensive and is still ongoing. As a consequence, we can infer a decline even though this species is not distinguished by foresters or loggers from the more widespread species A. borneensis.
Two localities on the map based on herbarium collections appear to be in protected areas: Maligan in Sabah and Usun Apau in Sarawak.