Investigating the role of historically isolated gallery forests outside the Congolese forest block as a refuge for African forest shrews
Résumé
Conditions that prevailed in rainforest faunal refuges during glacial periods of the Pleistocene, particularly their size, position and habitat characteristics, remain little investigated. After the peak of the last interglacial period of the Holocene (7000 years B.P.), the Guineo-Congolese rainforest has been reduced in size and isolated gallery forests emerged in the peripheral Northern Congo forest-savanna mosaic, mainly because of the reduction in rainfall. In the north of the Central African Republic, 400 km north of the present rainforest zone, up to the Sudano-Sahelian savannas, such gallery forests harbour several forest species of plants, birds and mammals related to West and/or East Congo faunal regions. This suggests that since the catastrophic destruction of central African rainforests, that culminated about 2500 years ago, these galleries could have mimicked the conditions that occurred in the Pleistocene refuges. We tested whether these natural gallery forests, outside the Congolese rainforest, could act as refuges for small forest mammals such as shrews. Composition and structure of shrew communities were studied in three main regions belonging to three river basins and two distinct phytoregions. They were compared to two other shrew communities located within the main Congolese rainforest, also in C.A.R.. None of the typical rainforest shrew species was collected within the studied isolated gallery forests. Thus, climatic and habitat characteristics within these gallery forests were presumably not suitable for these forest patches to act as climatic refuges for the forest shrew fauna.