Nutrient Supply, Dry-matter Production and Nutrient Uptake of Forest Tree Seedlings

The dry-matter production and nutrient uptake of forest-treeseedlings grown under controlled levels of nutrition in sub-irrigatedsand culture were investigated. Hardwood seedlings attainedgreater dry weight than conifer seedlings, and Pinus radiataa greater dry weight than P. contorta and P. nigra, but thesegreater dry weights were not related to greater leaf/weightratios, although seed size may have been an important influenceon final seedling dry weight. P. radiata was found to have alower requirement for P than P. contorta and P. nigra in oneexperiment. The demand (total nutrient uptake per unit of time) made bythree species for nutrients upon a site was shown to dependmore upon growth-rate per annum than on efficiency (quantityof nutrients required to produce a unit of dry matter). It isconcluded that the ability of tree species to grow satisfactorilyon soils of low nutrient status depends largely on their abilityfor relatively slow growth. On the other hand, species showinggood response to favourable sites may also make satisfactorygrowth on poor sites.