Litter Fall and Decomposition in Stands of Mature <i>Pinus radiata</i>

SYNOPSIS Rates of litter fall in mature stands of Pinus radiata D. Don have been monitored at the Jonkershoek Forestry Research Station since 1976. Decomposition trials were laid out in June 1977. Litter fall has been collected on six sites in the Bosboukloof experimental catchment, subdivided into its constituent components, and each component examined for production and annual variation. Total annual litter fall for Bosboukloof is estimated at 3 721 kg/ha. Of this, needle fall constitutes 2 645 kg/ha or 71%. Seasonality of some components is very marked but difficult to express quantitatively. An harmonic analysis on needle fall is included. Rates of litter decomposition have been monitored by means of needle samples in glass-fibre and shade-cloth mesh bags, and branches and cones pegged out in the field. The mass loss for needles after two years was between 40 and 50%, that for branches 10%, and that for cones 3,5%. The mass of accumulated litter on the forest floor has also been sampled to obtain an estimate of turnover. The few chemical analyses which have been done indicate N, Ca, and Mg to be the most abundant elements in needle fall with a return to the forest floor of 17, 12 and 7 kg/ha respectively over one year. No significant seasonal variation in the nutrient content of returning needles was found. A further paper will be required to detail the results of nutrient analyses once these are complete.

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