Harvesting and agro-ecological zones effects on sustainability of Boswellia sacra in Oman.

The frankincense tree (Boswellia sacra) is the most famous economic plant in Oman. Recently, tree populations have rapidly decreased because of incorrect tree-tapping practices. In Oman, the scientific knowledge of frankincense trees is still insufficient, especially in terms of tree yield at different agro-ecological zones, the effect of the resin extraction method and cutting frequency on yield, and plant regeneration. The present study was carried out in four different agro-ecological zones. A total of 180 healthy, non-harvested frankincense trees with four replications were studied. The maximum yield of olibanum from an individual tree was obtained at the fourth tapping pick. The average yields of resin in four locations were 650g, 620g, 360g, and 470g per tree per season in 10 picks. The study showed a positive correlation between olibanum yield and stem diameter, crown size, trunk size, and the number of tapping spots. Whereas, an inverse correlation was found with tree flowering and elevation. Sustainable harvesting of frankincense trees involved limiting cut depth in the phloem, ensuring not to reach hardwood, avoiding cutting in practical places in the tree bole, keeping a distance between cuts, using the traditional tapping method, and specifying periods of time in which tapping is prohibited.