Characteristics of soil and productivity of Pinus radiata (D Don) in New South Wales .I. Relative importance of soil physical and chemical parameters

Abstract

The objectives of the study were to determine whether selected soil physical and chemical parameters could be used as predictors of site and the productivity of Pinus radiata (D. Don). The study was carried out in the Lithgow district of New South Wales. Sixty plots were located in first-rotation unthinned stands of P. radiata of age 11 years. None of the stands had received fertilizer. The stands were selected to cover a wide range of merchantable volume production (0-175 m3 ha-1), and were located on a range of geological types including siltstone, medium-grained quartz sandstone, conglomerate, and rhyolitic tuff and lava. Soil depth was positively correlated, and per cent sand negatively correlated with all stand production variables. No other soil physical-or chemical variables were correlated consistently with stand variables. Discriminant analysis was used to test for the ability of a selected subset of soil physical and chemical variables to discriminate (a) between three volume production classes, and (b) between three geological groups. Soil depth, per cent sand, and total nitrogen contributed to two functions which discriminated between volume production groups. Cation exchange capacity, Bray phosphorus, per cent sand, exchangeable sodium, and total nitrogen contributed to two functions which discriminated between geological groups. Thus soil physical parameters were predominant in discriminating between volume production groups, and soil chemical parameters were predominant in discriminating between geological groups.