Impact of thinning of Acacia mangium plantation on soil chemical properties

This study was conducted to determine soil organic carbon, nitrogen, available phosphorus and pH at 3 soil depths under different ages and cycle of Acacia mangium after thinning of planted forest as well as to determine their variability in a tropical forest. Composite soil samples were collected at depths of 0 - 5, 5 - 10 and 10 - 30 cm in each plot and were analyzed for organic C, total N, available P and pH. Composite surface litters were analyzed for total C, N, P, Ca, Mg and K. Soil C and N were significantly higher at 0 - 10 cm depth in the 2nd cycle of A. mangium which were 0 - 3 months older than the natural forest. Available phosphorus decreased in the 1st rotation of Acacia mangium of more than 20-year-old stands and in plots which underwent thinning. Soil C, N, P decreased with increasing soil depth. Calcium in leaf litter of more than 20-year-old stands was significantly lower than in the other study plots. N, P and K concentrations were higher in leaf litter of thinned plots and in more than 20-year-old stands