Factors affecting survival of seedling of Afzelia africana, a threatened tropical timber species in West Africa

Abstract

4 Understanding abiotic and biotic factors afecting the survival of seedlings of threatened species such as Afzelia africana is fundamental for restoration and sustainable management purposes. This study used seedling individual-level morphological data and plot-level data to assess the efect of abiotic (season, elevation, soil type and terrain slope) and biotic (seedling initial density, basal diameter, height and number of leaves, insect and fungal infection, insect herbivory, mammal herbivory, vegetation type, adult conspecifc density and diameter, and heterospecifc density and diameter) factors on the survival probability (at individual level) and survival rate (at plot level) of seedlings of A. africana in the Pendjari Biosphere Reserve. Generalized Linear Mixed Models (GLMMs) were used for data analyses. At individual level, we found that the survival probability of A. africana seedlings increased with initial height, but decreased from wet to dry season. At plot level, the survival rate of A. africana seedlings also decreased from the wet season (0.72±0.05) to the dry season (0.18±0.04) and was inversely proportional to seedling basal diameter (P=0.024) and density of conspecifc adults (P=0.016). There were also positive efects of seedling initial height (P=0.026) and mean diameter of conspecifc adults (P=0.037) on survival rate. Among abiotic factors, only terrain slope showed signifcant and negative efect (P=0.028) on the survival rate, suggesting higher survival rate on fat terrain. Our fndings suggest that sustainably managing seedlings of A. africana would require accounting for conspecifc neighboring efect, terrain slope and season-specifc actions. Practical aspects of these factors were further discussed.