Regeneration and resin yield of boswellia papyrifera (Del.) hochst. In the Blue Nile State

The frankincense tree, Boswellia papyrifera, is an important resource in the dry lands of the Blue Nile State. However, its populations are declining due to many biological and environmental factors. Addition, there was very few regeneration of the species in its natural habitat. The aim of this study was to make available silvicultural and management tools for better understanding of using it for optimum and sustainable resin production. These will consider: the natural regeneration of B. papyrifera and the recruitment of the species via artificial regeneration namely seedlings and branch cuttings as well as the effect of time of tapping, direction and elevation (altitude) on resin yield. Soil samples were collected and carried out from B. papyrifera site in the dry season. Eight sample plots 2x2 m were randomly selected and arranged in eight replications, and irrigated regularly every 2 days to enhance seed germination. In the field natural regeneration survey was carried out by counting the young seedlings grown in the field for two periods before and after the rains. Five transect (blocks) were selected randomly in the three levels of the hills (foot, slope and top). Seed germination test was carried out to determine the viability of B. papyrifera seeds. In the first test seeds were sown immediately after seeds collection and the other one in the second season (seed were stored in bags for one year at room temperature) and also to assess the effect of seeds treatments on germination. Later, the seeds were sown in two types of soil, mixed soil (1 sand: 2 silt), and in soil collected from the site where B. papyrifera trees are growing to assess the growing rate on both soils. Branch cutting of one meter long and 4-7 cm in diameter were taken at three different dates namely: first of April, mid of April, and first of May. Tapping of B. papyrifera was done on trees selected randomly on each altitude or elevation (foot and up hill). Four tapping dates: 15/9, 15/10, 15/11, and 15/12 were applied. Three directions of tapping, (East-west; North- South and tapping in all direction (control) were tested. The results showed that B. papyrifera produced plenty of seeds that are stored in soil seed bank for natural regeneration. However, the young seedlings were almost absent after the dry season for many factors. A significant difference between seeds germination immediately after seeds collection and those seeds stored at room temperature and tested after one year from seed collection and, this means that B. papyrifera seeds have a very short life span, and there is no significant difference between treated and untreated seeds. Also a significant difference was reported between the mean numbers of seedlings grown at the foot the hill and the slope as compared to those grown on top of the mountain. No significant difference between the numbers of branch cuttings survived due to planting date and/or branch diameter, but the large size cuttings are better. Tapping date and direction showed significant (P 0.0001) differences between means of resin yield per tree. Tapping towards the sun light gave better results. The study showed that tree altitude had no effect on resin yield per tree