NUTRIENT BALANCE IN FORESTS OF NORTHERN TASMANIA .1. ATMOSPHERIC INPUTS AND WITHIN-STAND CYCLES

Eucalypt forest soils in northeastern Tasmania are ammonifying and contain low concentrations of extractable P. inorganic N and exchangeable cations, irrespective of underlying geology. Litterfall was proportional to productivity and could be described by a climatic index. Nutrient return in litterfall was unaffected by soil type and was the dominant transfer of N, P and Ca. Significant amounts of N (up to 8 kg ha-1 year-1) and other nutrients were added to the forests in rain. Although rainwater quality varied with distance from the coast, total nutrient input was dominated by rainwater quantity. Nutrient cycles and inputs were comparable with those found in other Australian forests of similar productivity. Soil in a cool-temperate rainforest was more organic than eucalypt forest soils and contained higher concentrations of extractable P, inorganic N and other nutrients. Litterfall in the rain-forest was rich in P, relative to the eucalypt forests, but poor in Mg. Nutrient absorption by the rain-forest root mat was more effective than that in eucalypt forests.