Assessment of the African baobab (Adansonia digitata L.) populations in Namibia : implications for conservation

Abstract

This study assessed the population structure of baobabs (Adansonia digitata) in Kunene, Omusati, Otjozondjupa and Zambezi Regions in northern Namibia. Data were collected from 240 trees in randomly selected baobab clusters. The stem girth at breast height (gbh, converted to stem diameter), height and crown diameter were recorded for each individual tree. Any sign of damage on the stem was recorded. Average stem densities were determined and compared between regions. Stem number per diameter classes were presented in histograms. The highest baobab density (6.7 stems per ha) was observed in Omusati Region and the lowest (0.2 stems per ha) was observed in Otjozondjupa Region. A J-shaped stem diameter distribution was observed in Zambezi Region and an inverse Jshaped distribution in Kunene Region. Bell-shaped distributions were observed in Otjozondjupa and Omusati Regions. The percentage of damaged stems in the sampled populations showed more damaged than undamaged baobabs in Kunene (63%), Omusati (83%) and Otjozondjupa (95%), but in Zambezi there were fewer damaged (46%) stems. Elephant damage accounted for 41% of the damaged stems whereas human damage was 59%. Selective protection of large baobabs by communities may attribute to the high densities and occurrence of trees in larger size classes in comparison to juveniles. Overall, the baobab population is currently considered as stable in Namibia. However, factors that negatively affect recruitment and establishment of baobab need to be monitored to ensure that a higher proportion of young trees survive. The study recommends protection and propagation of baobab seedlings in order to maintain viable populations of the species. Sustainable harvesting practices of baobab bark is also recommended.