Effects of Natural Forest, Plantation Forest and Grazing Land on Soil Microbial Biomass and Soil Enzyme Activities in Ethiopian Highland

Microbial biomass and enzyme activities play a crucial role on availability and cycling of nutrients in soil ecosystems. The main objectives of the study were to determine the effect of natural forest, plantation forest and grazing land on soil microbial biomass carbon and nitrogen and soil enzyme activities in Gelawudios, Ethiopia. To determine soil microbial biomass C and N fumigation-extraction method was followed and for enzyme activities a fluorometric enzyme assay method based on methylumbelliferone-linked (MUF) was used. Microbial biomass carbon and nitrogen were highly influenced by the land use systems following the order: natural forest>plantation forest>grazing land. Under different tree species microbial biomass carbon was not statistically differing however, microbial biomass nitrogen showed significant difference among tree species. Enzyme activities of β- xylosidase and β-Glucosidase in soils of all tree species under natural forest except Apodytes dimidiata were much higher than the plantation forest and grazing land. In our study enzyme activities had closely positive correlated with soil organic C and also pH of the soil. Natural forest area had the limitation of N, plantation forest and grazing land had the limitation of P and C.

Keywords: Natural forest; Grazing land; Microbial biomass; Plantation; Enzyme activities