Growth following fertilisation of thinnedPinus radiatastands near Canberra in south-eastern Australia

Abstract

Summary The results of three field trials which were established in 1976 to determine the feasibility of increasing wood production of Pinus radiata by fertilisation of thinned stands are described after four years of growth following the fertilisation treatments. The stands of about 20 years of age were producing an average of 14 m3 ha−1 stem-wood per year. The extra volume of wood growth resulting from fertilisation averaged 4.2 m3 ha−1 a1 for all sites, and 5.9 m3 ha−1 a−1 for the two most responsive sites, the latter being 37% over that obtained from unfertilised stands. Fifty per cent of the extra volume was added to the largest one-third of trees in the stands. A dominant tree of diameter (bhob) 27.0 cm in 1976 became 30.7 cm in 1980 if unfertilised and 32.8 cm if fertilised, an increase of 2.1 cm. The responses obtained were inversely proportional to both the relative growth rates of unfertilised stands following thinning, and to the nitrogen concentration in the foliage of unfertilised trees measu...