Population structure and conservation of Cola nitida and Garcinia kola in a West African rainforest area

Abstract

Native multi-purpose tree species in West Africa, Cola nitida and Garcinia kola have the potential to advance agroforestry practices in the sub-region. There is limited information on the ecology of both species which are currently characterised by low yield (fruit). This study investigated the influences of vegetation type on the population structure and floral association of both species in Nigeria. Data were collected using a purposive sampling design. Dendrometric variables of all the subject trees were measured, and all plant species associated with the subject tree species were enumerated across their places of natural occurrence. A 3-parameter Weibull Distribution Function was used to describe both species' diameter and height structures. Data were analysed using descriptive and inferential statistics. A total of 84 and 71 plant species were found accompanying G. kola and C. nitida, respectively, in both zones. The height and stem diameter distribution of the two species showed a bell-shape population structure, suggesting an unstable demographic pattern. The diameter distribution is skewed to the right, indicating the predominance of adult individuals. The height–diameter relationships show a monotonic increment. Both species coexist freely with other species and can be used in agroforestry practices.