Australian Forestry Journal - Abstract

Reference:

2009 Vol72(2) Page 99

Title:

Effect of phosphorus and potassium fertiliser on stem form, basic wood density and stem nutrient content of Pinus patula at various stem heights

Author(s):

J.W. Crous, A.R. Morris and M.C. Scholes

summary:

The effect of silvicultural treatments on volume production, tree form, basic timber density and stem nutrient content with changes in tree height were investigated by destructively sampling 32 Pinus patula trees in a fertiliser × weed control trial at rotation age (15 y). Sixteen trees, covering the range of stem diameters, were selected from both the control (no fertiliser applied) and Split 80/80 (20 kg ha–1 of P and of K applied at planting as a spot application, followed by a broadcast application of 60 kg ha–1of P and of K, after pruning at age 5 y) treatments. At 15 y of age the split application of 80/80 PK fertiliser increased the timber production by 32% (89.5 m3 ha–1) compared with the control. Fertiliser decreased basic wood density by 7% at ground level and by 5% over the entire stem. The nutrient concentration of N, P and K in the stemwood and stembark increased with an increase in stem height. The changes in nutrient content and basic wood density with tree height clearly indicate the need to sample at more than one height to obtain an accurate average or total value for each tree. The increased concentration of P in the wood, in addition to increased timber production, will result in a greater export of nutrients in harvested timber from compartments that receive fertiliser compared with those that do not. Keywords: plantations; yields; nutrition; fertilizers; stem form; wood density; concentration; bark; wood; Pinus patula