STATUS OF SOIL MICROBIAL POPULATION, ENZYMATIC ACTIVITY AND BIOMASS OF SELECTED NATURAL, SECONDARY AND REHABILITATED FORESTS

Substantial clearance of forests and conversion of forest into various land use types contribute to deterioration of soil fertility and associated nutrients loss. Six subplots (20x20 m) were established at each study plot and soil samples were collected at the depths of 0-15 cm (topsoil) and 15-30 cm (subsoil). Soil microbial population was determined using spread-plate technique. Fluorescein Diacetate hydrolysis was used to assess the amount of microbial enzymatic activity for each forest plot. Soil Microbial Biomass C (MBC) and N (MBN) were extracted using chloroform fumigation extraction technique and the amount of MBC was determined by dichromate digestion, while MBN via Kjeldahl digestion technique. Longer period of time after planting as in enrichment planting compared to mono planting of S. leprosula plantation showed that, restoring and recovery of the planted forest needed time. Deforestation activities decrease soil biological activities; however, proper forest management and rehabilitation activities are able to restore the condition of degraded forest land to its original state.