Diversity and structure of terrestrial small mammal communities in different vegetation types on the Accra Plains of Ghana


All correspondence to: J. Decher, Department of Biology, University of Vermont, Marsh Life Science Building, Burlington, Vermont 05405-0086, U.S.A.


Small mammal communities (shrews and rodents) were studied using mark-and-recapture techniques from November 1991 to June 1992 at six sites on the Accra Plains of Ghana. The sites were two traditionally protected ‘sacred groves’, two plots in the legally protected Shai Hills Resource Reserve, and two fire-protected sites: secondary forest and a Gmelina tree plantation. A total of 241 individuals representing four species of shrews and nine species of rodents was caught. Abundance, diversity, and composition of small mammals varied greatly between sites. Praomys tullbergi was the most abundant species in the sacred groves, whereas Mastomys erythroleucus dominated in the fire-protected site and in the plantation. The more open grassland areas in the Shai Hills were dominated by Lemniscomys striatus and Uranomys ruddi. Shrews were caught only in forests having dense leaf litter. Legally protected reserve sites had the highest diversity of small mammals but population densities were low. In contrast, the sacred groves had lower diversity levels but much higher population densities, resulting in 1.9 to 14.6 times the biomass of any of the other sites. The rodents Mus minutoides and Hylomyscus alleni and the shrews Crocidura buettikoferi and C. lamottei were found only in the sacred groves. Sacred groves play an important socio-cultural role. Their local ecological and economic importance as reservoirs for rare and useful plants is well known. This study shows that they are also important refuges for certain small mammal species and support characteristic mammal communities. An attempt to measure the impact of the invading exotic tree Azadirachta indica (neem tree) on small mammals was inconclusive, although trapping success was low in areas with dense stands of neem.