Comparison of the ecology and distribution of the Poaceae flora on inselbergs embedded in savannah (Benin) or in rain forest (Western Central Africa)

Abstract

The ecology and distribution of Poaceae species found on 12 inselbergs embedded in savannah and woodland (Benin) and on 25 inselbergs enclosed in rain forest (CEG: Cameroon, Equatorial Guinea and Gabon) are described. A total of 77 species were observed, 46 in Benin and 36 in CEG. Five species were strictly saxicolous in Benin and three in CEG, but most species (83%) were also present in the vegetation surrounding the inselbergs (the matrix). In Benin, 46% of the species were present on half of the inselbergs, while only one species did so in CEG. This unequal distribution of the species amongst sites in CEG could originate from dispersal limitation due to the strong ecological contrast between the inselberg biotope and the rain forest. Ecological conditions on the inselbergs are more similar to that of a savannah and woodland matrix, which could explain the homogeneity of inselberg vegetation in Benin. In CEG, four species were mainly distributed outside the lowland rain forest region: two in savannah and woodland, and two in mountainous vegetation. The discontinuous distribution of these species with inselberg satellite populations in the lowland rainforest is probably related to Quaternary vegetation changes. Inselberg in both study area contribute significantly to the regional species diversity by the presence of strictly saxicolous species or of species from other phytochoria. The inselberg habitat should therefore be considered in conservation policies. © 2006 Royal Botanical Society of Belgium.SCOPUS: ar.jinfo:eu-repo/semantics/publishe