Local management practices influence the viability of the baobab (Adansonia digitata Linn.) in different land use types, Cinzana, Mali

摘要

In west Africa, the alarming rate of land use intensification and the assumed deterioration of parkland species calls for assessments of locally valued non-timber forest product (NTFP) yielding populations. This study focused on the baobab tree, Adansonia digitata Linn., in Cinzana, Mali. Here by conducting biological inventories in different land use types and interviews we addressed the following central questions. (1) How does the harvesting of baobab NTFPs in different land use types (fallow, cropland, and village (habitation) areas) affect the viability of its population? (2) By which ways do humans, other than by harvesting, affect the viability of the population? The viability of a population is, in this study, treated as a characteristic that is determined by the mature population size and its regeneration potential (recruit population). Baobab products in Cinzana are used on a regular basis and valued in a cultural context, like in many parts of west Africa. For the local society, the sustained viability of the baobab populations is therefore essential. Fruit harvesting has an impact on dispersal and establishment, while leaf harvesting causes mutilation that reduces the number of fruits on each tree. Mutilation was more severe in cropland than in fallows, and cropland individuals were most prone to damages from plowing and livestock. The baobab populations were, however, more dense and comprised more recruits, in cropland and village areas compared to fallows, and seedlings were in fact not found in fallow. These differences are explained by management practices related to the land use type. In addition to the differences in baobab density and population structure between cropland and fallows, the weak correlation between density of recruits and mature individuals testifies to the importance of the specific ecological role that humans play in baobab dispersal and establishment. Clearly, harvesting is not the only way by which humans influence the viability of baobab populations. Some practices are beneficial, either intentional (e.g. seedling protection, transplanting) or unintentional (e.g. dispersal of seeds in garbage), while others are detrimental (e.g. livestock browsing, plowing). At present local management practices contribute to sustain the viability of the species. The results point to the fact that the baobab population is not declining but in need of management that secures the maintenance of a genetically diverse population