LITTERFALL, LITTER AND ASSOCIATED CHEMISTRY IN A DRY SCLEROPHYLL EUCALYPT FOREST AND A PINE PLANTATION IN SOUTH-EASTERN AUSTRALIA - 2 - NUTRIENT RECYCLING BY LITTER, THROUGHFALL AND STEMFLOW

This paper concerns recycling of the major nutrients (N, P, Ca, Mg, Na and K) by litterfall, throughfall and stemflow in a dry sclerophyll e ucalypt forest and a nearby Pinus radiata plantation of similar tree d ensity and basal area. With the exception of Mg, the concentration of these nutrients in eucalypt leaf-fall were substantially higher than i n pine needlefall. The eucalypt nutrient input was greater owing to la rger mass of litterfall, as well as higher concentrations. There were inverse relationships between N and P concentrations and amount of lea f-fall for the eucalypts and needlefall for the pines. Mg was positive ly correlated with eucalypt leaf-fall. For the other components and el ements the relationships were random. The proportion of particular nut rients recycled by litterfall, and throughfall and stemflow, varied fo r both forests. For Ca, only 6 and 12%, for eucalypts and pines respec tively, was recycled by throughfall and stemflow, compared with 52 and 68% of potassium. The amount of nitrogen recycled differed between th e forests, in a way that was consistent with the eucalypts being nativ e to a nitrogen-poor environment. Amounts of floor-litter collected in the eucalypt forest from two fairly distinct layers, the loose and co hesive litter, were similar. The concentrations of Mg and Na were simi lar in both layers, but the other elements varied substantially. The N concentration of the cohesive litter was more than double that of the loose layer, whereas its P concentration was only 10% of the loose la yer value, Selected chemical analyses on the total tree biomass of the eucalypt forest showed that the concentration of elements increased i n the order; wood, twigs, fine twigs and leaf, and from large diameter wood to fine twigs. However, the concentration in fine twig and leaf components varied between the elements. For Ca, P and K, the fine twig values were greater than the leaf values, but the reverse applied to the other elements. The concentrations of almost all elements in all c omponents were substantially higher in Eucalyptus mannifera than in E. rossii, E. macrorhyncha and E. melliodora. The nutrient content of th e floor-litter was compared with the twig, fine twig and leaf componen ts of the live biomass, i.e. the components most likely to become read ily decomposable floor-litter. For all elements except N, the amount i n floor-litter was similar to the amount in the biomass components. Th is was because the concentration of N in the floor-litter was much gre ater than in these components of the biomass. (C) 1998 John Wiley & So ns, Ltd.