The influence of logging and animal grazing on the litter layer and water infiltration rate of soils in plantation forests

Investigations to show the extent of soil disturbance caused by logging and animal grazing were carried out in one of the forest plantations in Tanzania. Water infiltration capacity and ground litter thickness were used as a measure to determine the extent of soil disturbance. Data on infiltration rate and litter depth on stands under different management practices were collected, analysed and compared with data from the nearby undisturbed natural forests. The study found that logging and animal grazing reduced water infiltration rate in the soil and deposition of ground litter. Depending on the management practice or the condition of the stand, the rate of water infiltration was reduced from 36 to 96% when compared to water infiltration rate experienced in the nearby natural forest. While in undisturbed natural forest the mean litter depth was 11.1 cm, on clearfelled and grazed stands, the litter depth was only 0.9 cm. The effects of low water infiltration rates and low litter deposition are discussed and measures aimed at increasing water infiltration rate and litter deposition are suggested.