CULTURABLE MICROBIAL POPULATION DYNAMICS DURING DECOMPOSITION OF COLA NITIDA LEAF LITTERS IN A TROPICAL SOIL SETTING

The culturable aerobic heterotrophic bacterial and fungal distributions and population dynamics during decomposition of kolanut leaf litters were investigated between February 2002 and January 2003 using standard litterbag studies and microbial cultivation techniques in a confined and unconfined setting. Organic carbon and soil pH were also monitored in the experimental plot. Bacterial counts ranged between 6.0 × 10 5 and 8.1 × 10 7 cfu/g wet weight of litter or soil, while fungal counts were of the order of 10 3 – 10 4 cfu/g wet weight of litter or soil. Counts of bacteria and fungi were highest during the rainy season months and reduce on either sides of the rainy season divide. Bacteria diversity index ranged between 0.42 and 1.69, while fungal diversity index varied between 0.56 and 2.54, and a total of eighteen culturable bacterial and fourteen fungal strains were identified. The organic carbon contents of the leaf litters were consistently significantly (p < 0.05) higher than those of the soils in the experimental plot and ranged between 13.42 and 59% for the leaf litter and 4.02 – 14.76% for the soil samples. pH of the soil samples were observed to vary between 5.3 and 7.98. We conclude that decomposition of kolanut leaf litters in a confined or unconfined setting does not appear to significantly affect the stability of the culturable microbial milieu.