Effect of position of tapping, tree stem diameter and tapping tools on frankincense yield of Boswellia papyrifera in South Kordofan state, Sudan.

摘要

Two experiments were conducted in a natural stand of Boswellia papyrifera at Um Abdalla forest reserve, Sudan, during October in the 2002 growing season to determine the effect of position of tapping, intensity of tapping (number of tapping incisions) and tree stem diameter on resin yield, and to determine an improved procedure and suitable tool for tapping the tree. In the first experiment, the two variables (treatments) were tree stem diameter (10-15, 16-20 and >20 cm DBH) and intensity of tapping stem, which was tested at two levels namely tapping two opposite sides (north and south) and tapping four sides. In the second experiment, the position of tapping was tested in three levels (50, 100 and 150 cm) relative to stem base. The second experiment looked at two tapping tools (Mengaf which was used for tapping B. papyrifera and Sonki which was used for tapping Acacia senegal). Results showed that tree stem diameter had a very significant effect on frankincence yield, those obtained from 10-15 and 16-20 cm stem diameter were 60 and almost 38% lower that those 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 insignificant. The position of tapping also had a significant effect on resin yield. The yield increased with the increase in the level of tapping. The yield from the smallest diameter was 40% lower than the yield obtained from the highest level of tapping. The tapping tools used had a significant effect on resin yield. Tapping by the Mengaf tool yielded nearly twice than that of Sonki. The interaction effect between position of tapping and tapping tools was insignificantly different. The results suggest that yields of over 800 g per tree may be expected from trees over 20 cm dbh using the Mengaf tool and tapping over 1 m from the ground level and tapping on 4 sides.