Article révisé par les pairs
| Résumé : | The ecology and distribution of thirty-seven Melastomataceae species found on 29 inselbergs in the rain forest of Equatorial Guinea, Gabon, and Cameroon are described. The relative contributions of climatic determinism, and stochastic and historical processes to the present distribution of the species amongst the study sites are investigated. Inselbergs are rock outcrops enduring very harsh edaphic and microclimatic conditions, forming "xeric islands" in the rain forest, where natural grasslands develop. For each Melastomataceae species, the habitats where they were collected on the inselbergs and in other biotopes were listed, and their phytogeographical distribution was established. Three species are restricted to rock outcrops. Most species are distributed inside the Guineo-Congolian Region. Three species have disjunct distributions on rain forest inselbergs and have their main distribution area outside the forested zone. The distribution of the species amongst the inselbergs is correlated to the altitude and the annual rainfall of the sites, and to inselberg geographical location. This correlation of the species distribution with the geographical location of the inselberg is attributed to the spatial autocorrelation of environmental variables and to the combined effects of the history of past vegetation changes due to climatic fluctuations and dispersal limitation. |
