Division of Forest Research, CSIRO, Private Bag, P.O., Wembley, W.A. 6014, Australia

With increasing age of the stands, the concentration and amounts of Ca, K, Mg, Na and Cl in throughfall increased. The amounts of Mg, Na and Cl in stemflow from the overstorey were also greatest in the older stands. Although concentrations of nutrients in stemflow from the tree stratum were higher than from the understorey, the quantities of nutrients transported to the forest floor in stemflow from the understorey were greater because of its greater volume.

Rainfall is the major source of Na (64–91%) and Cl (51–79%) and it also contributes significantly to Mg (19–50%) accessions. Of the nutrient pathways between canopy and forest floor, litterfall accounts for the largest proportion of N (89–93%), Ca (80–87%) and P (67–79%) recycled in the karri forest. About equal amounts of K are transferred in litterfall, throughfall and stemflow with approximately 80% of stemflow K originating from the understorey strata.