Nutrient cycling and nitrogen mineralization in eucalypt forests of south-eastern Australia

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Nutrient pools in litter and soil and the major nutrient transfers and additions in rainfall, throughfall and litterfall were measured in eight mature, undisturbed eucalypt forests covering a range of species, climate, productivity and soil type. Litterfall is the major pathway for the return of N, P, Ca and usually Mg, to the soil. The forests covered almost the range of litterfall reported for eucalypt forests and, in conjunction with published data, litterfall was strongly related to climatic variables. Extractable P in the soil and P concentrations in litter and litterfall were significantly higher in two sub-alpine forests (Eucalyptus pauciflora andE. delegatensis) than in all other forests. In general, nutrient turnover, particularly N turnover, was related to the rate of organic matter turnover. Rates of organic matter turnover in these forests and in other studies of eucalypts were correlated with climatic conditions using the simple climatic scalar developed by Vitousek. Nitrogen turnover, especially that proportion cycling via leaf litterfall is primarily a function of organic matter turnover, but litter quality appears also to have an influence.