Nutrient Cycling in a Eucalyptus obliqua (L'hérit.) Forest. I. Litter Production and Nutrient Return

Total litter fall in mature Eucalyptus obliqua forest is typical for warm temperate forest, in the range 3.6-5.5 t ha-1 yr-1. Fifty per cent of the litter fall occurs in the summer months, and the seasonal rate of litter fall is dependent primarily on temperature. The concentration of nutrients in litter fall varies significantly throughout the year. Prior to litter fall, about 70% of the phosphorus is withdrawn from that portion of the biomass which is to fall as litter and the amount of phosphorus cycled in the litter is therefore very small. At the other extreme, calcium is immobilized in large quantities immediately prior to litter fall. The internal, or 'biochemical', cycling of phosphorus is probably of major significance in the functioning of eucalypt forests on Australian soils characterized by a low phosphorus content.