RELICT FOREST IN THE BANFORA CLIFF: A UNIQUE FOREST COMMUNITY IN THE NEIGHBOURHOOD OF BOBO-DIOULASSO, BURKINA FASO

The Banfora cliff are home to a wealth of flora and fauna. Endemic species are found in its forests, as well as species of outstanding interest such as Albizia dinklagei, Acridocarpus chevalieri or Warneckea fascicularis, which are found nowhere else in Burkina-Faso. This is also the case with some insect species, such as Dicronorhina kouensis or Stephanorhina guttata. However, these forests are under threat, especially around Bobo-Dioulasso where the native fauna has already become partly extinct. Comparisons were made between the Banfora cliff sites and between these and other forest sites in the Bobo-Dioulasso region. Biological diversity is very high among these forests, and the dispersion of species suggests that they are remnants of much larger forest areas. The forest vegetation on the cliffs appears to be of three types: dense dry forest, characterised by Guibourtia copallifera, which may represent the original old-growth forest stock before it was invaded by savannah vegetation; dense humid forest, represented by most of the riparian species, which probably evolved along the river network from the humid forest mass; and relict old-growth mountain flora that depends on the sandstone cliff environment, with Warneckea fascicularis, to which rock species could be attached, as the sole representative. The rodent community in the Banfora cliff forest sites is a mixture of typically forest-dwelling species (particularly Praomys rostratus) in the least disturbed zones and highly anthropophilous species (like Rattus rattus) in the sites most severely degraded by human activities. Most insect species probably originated in the humid forests of Cote d'Ivoire, with some influence from Mali, like Coeliades aeschylus, or Togo, like Dicronorhina kouensis, both of which tend to be found in the Guinean savannah zone close to gallery forests. As these species are neither found in the South, nor respectively in the East and the West of Burkina Faso, the Banfora cliffs may be a meeting point for different types of fauna, hence its outstanding biodiversity interest.