EFFECT OF POSITION OF TAPPING, TREE STEM DIAMETER AND TAPPING TOOLS ON FRANKINCENSE YIELD OF BOSWELLIA PAPYRIFERA IN SOUTH KORDOFAN STATE, SUDAN

Abstract

ABSTRACT Boswellia papyrifera (Del.) Hochst is an important multipurpose tree in the savanna belt of South Kordofan. The tree produces frankincense—locally known as Luban—which is used as incense and as a raw material in the food, perfume and pharmaceutical industries. In Sudan frankincense is used in homes to produces a nice smell from its smoke. The economic important of frankincense gum is well recognized by Sudanese merchants in the local market and for export. Resin productions in South Kordofan represent the main source of income during hard times. Recently, the production has declined as a result of the increase in human and animal populations, drought and desertification, seasonal fire and poor natural regeneration of the trees. Despite its importance little information on how to improve resin production is available. Therefore, two experiments were conducted in a natural stand of Boswellia papyrifera at Um Abdalla forest reserve during October in the 2002 growing season. The objectives were to determine the effect of position of tapping, intensity of tapping (number of tapping incisions) and tree stem diameter (DBH) on resin yield, and to find an improved procedure and suitable tool for tapping the tree. The design of both experiments was a two factor, randomized complete block design. The resin of each tree was collected after four weeks, dried in the shade for 2 weeks and then weighed. In the first experiment the two variables (treatments) were tree stem diameter (DBH) (3 size classes—10–15 cm, 16–20 cm and >20 cm) and intensity of tapping stem (number of tapping incisions) which was tested at two levels namely tapping two opposite sides (North and South), and tapping four sides. In the second experiment position of tapping was tested in three levels (50cm, 100cm and 150cm) relative to stem base. The second experiment looked at 2 tapping tools (Mengaf which was used for tapping Boswellia papyrifera and Sonki which was used for tapping Acacia Senegal). The result showed that tree stem diameter (dbh) had a very significant (P < 0.01) on frankincense yield, that obtained from 10–15 cm and 16–20 cm stem diameter being 60% and almost 38% lower than that of stems over 20 cm stem diameter. There were no significant differences between the yields when tapping on two or four sides. The interaction effect between tree size and tapping intensity was not significant. Position of tapping also had a significant (P ≤ 0.05) effect on resin yield. The yield was increased with increase in the level of tapping. The yield from the lowest (50 cm) was 40% lower than the yield obtained from the highest level of tapping (150cm). The tapping tools used had a significant (P ≤ 0.01) effect on resin yield. Tapping by the Mengaf tool gave a total yield nearly twice that for the Sonki tool. The interaction effect between position of tapping and tapping tools was not significantly different. The results suggest that yields of over 800 g per tree may be expected from trees over 20 em dbh using the mangaf tool and tapping over l m from the ground level and tapping on 4 sides; more intensive tapping is thought to be excessive and may cause the death of the tree.