Site productivity of Gmelina arborea plantation forest in tropical region
2005
Agus, C.
Sustainable Forest Management (SFM) of short-rotation tropical plantations may be determine by the balance between tree growth, nutrient uptake and soil fertility. We compared soil fertility and nutrient cycling across a range of site quality within six-year-into poor, moderate and good productivity classes based on height growth. The mean stand height showed approximately 40 m ha. The ratios of biomass and nutrient amounts of aboveground biomass on the poor, moderate and good sites were 1: 2: 3. The littlefall of yemane plantations in the moderate and good sites was approximately 8 and 12 Mg ha yr, respectively, distributed almost evenly throughout all months during the year. The nutrient availability on the three sites was small. The good site provided greater amount of available-P, exchangeable-Ca and Mg, T-P, T-Ca and T-Mg which could be circulated in the ecosystem than that of the moderate and poor sites. Nitrogen and phosphorus were the nutrients limiting yemane growth and regeneration. Alternatively, site productivity could be maintained by managing closed nutrient cycling or by practicing mineral and biological fertilization. Yemane plantation forest was supported more by nutrient cycling rate than by amount of nutrient availability in the soil. The good site had better productivity and more rapid nutrient circulation than that of the poor and moderate sites.
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