Productivity of first and second rotation stands of radiata pine on sandy soils. I. Site factors affecting early growth

Summary Two approaches have been used in a long term study of the productivity of first and second rotation crops of Pinus radiata on sandy soils in south-west Victoria. These approaches have involved (i) long-term comparisons of growth of the second rotation with that of the first rotation on the same site, and (ii) an examination of tree growth on matched first and second rotation sites in relation to physiological, edaphic and environmental factors. This paper presents results of the second part of the study obtained during the first year after planting. The establishment practices used for planting the matched first and second rotation sites included treatments designed to resemble as closely as possible the cultural treatments in use one tree generation ago. First year growth on unburnt second rotation sites was markedly better than that on first rotation sites which, in common with past practice, were burnt following hand clearing of the native eucalypt forest. The better early growth on unburnt second rotation sites was strongly related to higher nitrogen uptake and more favourable leaf water potentials. The significance of these results in relation to maintenance of site productivity is briefly discussed.