Rapid conservation assessment of Boswellia sacra in Oman reveals complex threat and population patterns

Summary

Boswellia sacra is an iconic dryland tree in southern Arabia and Somalia. A cultural keystone species, it produces frankincense resin long used for its medicinal and aromatic qualities. Recent research has indicated population declines and unsustainable exploitation of multiple species of Boswellia, including the Somalian B. sacra populations. However, information on the Arabian populations is minimal and contradictory. Therefore, we conducted a broad-scale rapid assessment of the B. sacra populations in the Dhofar mountains of Oman to map the species’ range, identify major threats, and predict if the same pattern of population collapse seen in other species is occurring in Oman. Based on field surveys and distribution mapping, B. sacra likely occupies a range of at least 3465 km² in Oman. We observed regeneration across almost all populations, with 97 % of transects including at least 10 % small trees or saplings. However, population patterns were variable; both reverse-J shaped and bell-shaped population structures were observed in different locations. Threats identified varied geographically, and included overgrazing, resin overharvesting, mining, insect/pest attacks, and wind/flooding. Grazing pressure was prevalent across many populations, while harvesting pressure was concentrated in specific areas. We conclude that the data do not currently indicate significant or widespread declines in B. sacra in Oman, as seen in other species. Still, given the burgeoning threats, improved socio-ecological management systems are needed to maintain this status. Key priorities include research to elucidate drivers of population patterns, improved rangeland management, enhanced monitoring and management of resin tapping, and identification of potential additional reserves.