Microbial activity is highly relevant for nutrient cycling and soil fertility in forest plantations. Due to the long growth cycles, continuous litter production and dead roots contribute to storage and increase of soil organic matter. Changes in soil and litter microbial biomass and activity under 1, 3, 5 and 13-year-old eucalypt plantations were evaluated. Soil and climate conditions were the same at the sites. Microbial biomass C and N were higher in litter than in soil. Then, litter could be an important sink of microbial C and N in eucalypt plantation. No increase or drop in microbial biomass and activity was observed as plantations grew older, probably because the soil and litter samples were from reformed plantations. Litter quality had a direct influence on litter microbial activity and microbial biomass C and N. Organic carbon and N content were the most reliable indicators to show changes in the soil under eucalypt plantations, while in the litter it were the microbial attributes and cellulose, lignin, and N content.
organic matter; nutrient cycling; forest soils
