Foliar nutrient concentrations in mixed-species plantations of subtropical cabinet timber species and their potential as a management tool

Foliar concentrations of N, P, K, Mg and Ca are reported for 12 rainforest timber species in five mixed-species plantings in the northern rivers region of New South Wales, Australia. The results are compared with data taken from natural stands, and with published records. Leaves of Dysoxylum mollissimum contained high levels of nitrogen (up to 4%), higher than foliar levels in the leguminous Castanospermum australe. Elaeocarpus grandis and Grevillea robusta performed best of all the species, but their growth was greatly reduced at some sites. Flindersia schottiana and F. brayleyana were the most consistent across sites, most species exhibiting strong site-species interactions. Some of these growth differences can be related to nutrient stress. The use of foliage nutrient analysis as a tool for early-growth diagnosis and management for optimal growth is discussed in the light of these results.