Brachystegia woodland of Arabuko Sokoke forest: Structure and regeneration dynamics with special emphasis on Brachystegia spiciformis

Abstract

Brachystegia woodland is a prominent vegetation type in the Arabuko Sokoke forest. This vegetation type is dominated by Brachystegia spiciformis, a species with high potential for timber and other uses. A study was initiated to assess the current status of the woodland and specifically to determine natural regeneration dynamics of the dominant Brachystegia spiciformis. Canopy analysis together with assessment of height and diameter distribution shows that the structure of the forest is tightly influenced by the distribution of B. spiciformis trees in the various size categories and canopy strata. However, this influence is not extended to in situ natural regeneration. Unlike other forest types, latent regeneration of the dominant B. spiciformis is extremely low. It appears that specific environmental factors are decisive in triggering gerimination. It is postulated that the critical factor governing germination is light. The canopy density controls this light factor such that a certain density level of the over-storey inhibits germination and regeneration of B. spiciformis . .The implication is that some canopy opening and disturbance may encourage regeneration of B. spiciformis.