Availability of nitrogen and phosphorus in forest soils in northeastern Tasmania

Summary Rates of N mineralization and of N uptake were measured in situ in three eucalypt forests and a cool-temperate rainforest, and were correlated with productivity. All of the soils had a high capacity for immobilization, and nitrification was insignificant. Changes in both organic and inorganic P fractions during in situ containment of soils were small. While the concentration of inorganic available P was not related to forest productivity, a measure of labile organic P was closely related both to productivity and to P in the microbial biomass. Estimates of inorganic- and organic-N availability were highly correlated with independent estimates of organic-P availability, and the results are discussed in relation to biological control of nutrient availability in the surface horizons of forest soils.