Published online by Cambridge University Press: 10 July 2009
Production and nutrient content of small litterfall were studied for one year in four plantations of Agathis dammara ranging in age from 7 to 35 years old, in a 12-year-old stand of Pinus merkusii and in an approximately three-year-old shrub community dominated by Eupatorium species. The dense Pinus plantation produced considerably more litter (10 t/ha/yr, with 5.5 t/ha as needles) than any of the Agathis stands (2.6–6.2 t/ha/yr; 2.3–3.5 t/ha as leaves) or nearby Lower Montane Rain Forest (6.8 t/ha/yr; 5.4 t/ha as leaves). Litterfall in the Agathis forests increased with stand age. The shrubs produced sizeable amounts of litter (3.4 t/ha/yr). The various species responded differently to a drought occurring during the study period.
Pine litter generally exhibited low nutrient concentrations (on average 9.2, 1.9, 2.5, 0.4 and 6.0 mg/g of calcium, magnesium, potassium, phosphorus and nitrogen respectively in needle litter), whilst concentrations in shrub litter were generally high (37.8, 4.9, 1.4, 1.05 and 21.5 mg/g for the same elements); Agathis litter usually showed nutrient concentrations that were intermediate between those for pine or shrub litterfall with only minor differences between stands. Comparison of the present findings with observations at other tropical sites suggests that nutrient content of litterfall in plantation forests may approach that of natural forests when the former become about 20 years old. Pine plantations may constitute an exception in this regard.