Field litterbag studies were conducted during the dry season between years 2000 and 2001 in typical semi-arid and arid agroecozones of West Africa to measure the dynamics of culturable bacterial and fungal communities in the topsoils. Five different agroforestry leaf litters namely Dactyladenia, Pterocarpus, Alchonea, Senna, and Gliricidia species were decomposed, and their effects on soil microflora were studied. Bacterial densities in all the studied plots of the two agroecozones varied from the order of 108 to 1010 cfu/g, while fungal densities ranged in the order of 103 and 104 cfu/g. Ecological zones impacted significantly (P < 0.05) on bacterial proliferation, but not on fungal growth. Sampling period significantly (P < 0.05) affected microbial density and the semi-arid agroecozone was more supportive of microbial proliferation than the arid zone. A total of nine predominant fungal species belonging to the genera Aspergillus, Scopulariopsis, Alternaria, Penicillium, Micromonospora, Trichophyton and Neurospora were observed in both the semi-arid and arid agroecozones, although their distributions under both agroecozones did not follow any definite pattern.