Size-class distribution of Anogeissus leiocarpus (Combretaceae) along forest–savanna ecotones in northern Ivory Coast

Abstract

Along eight forest–savanna transects at seven semi-deciduous forest islands in the southern Comoé National Park data on spatial distribution of tree-size classes and environmental parameters (fuel load, shading by upper tree layers, and soil depth) were collected. For dominant tree species, a sequential series was observed from the forest border into the forest interior. At the forest border, Anogeissus leiocarpus was the most abundant tree with juveniles (<1 cm dbh) reaching highest density values (mean of 502 individuals ha⁻¹) at the outer periphery of the forests. Regression analysis of juveniles of dominant tree species and environmental parameters resulted in a separation of forest and savanna species. Forest tree species regenerated well at forest sites, but also in the shade of A. leiocarpus stands. We conclude that (1) the studied forest islands advance against savanna by sequential succession, and (2) A. leiocarpus has a high potential to regenerate at savanna–forest boundaries under moderate fire impact and on rather shallow soils. The potential of A. leiocarpus to act as an important pioneer in the replacement of savanna by forest due to its effective regeneration at savanna sites and subsequent modification of site conditions, especially fire intensity by shading out savanna grasses, is discussed.