BELOW-AND ABOVEGROUND GROWTH OF EUCALYPTUS-NITENS IN A YOUNG PLANTATION - I - BIOMASS

The relative distribution of below-and above-ground biomass in an Euca lyptus nitens plantation was studied under a set of five fertilizer re gimes. In addition to a control (unfertilized) treatment, N and P fert ilizers were applied at a ratio of 2:1 with rates of N at 75, 150, 300 and 600 kg ha(-1) at 2 and 26 months after planting. There was a smal l response in stem diameter to fertilization by 34 months. Biomass of fine and medium roots was influenced by spatial variation in soil prop erties arising from cultivation as well as fertilization, but the effe cts of fertilization on root biomass was inconsistent. Biomass of coar se roots increased with the size of tree, and fertilizer treatments di d not influence the relationship between coarse-root weight and tree-s ize. There was a significant decrease in the amount of below-ground pr oduction per unit above-ground production of biomass with increasing r ates of fertilization. This change in distribution of biomass was main ly due to an increased contribution of coarse roots and a reduced cont ribution of branches to total biomass in fertilized trees, Thus, appli cation of fertilizers to ameliorate even a modest nutrient limitation in plantations can change relative distribution of biomass in below-an d above-ground components of trees. (C) 1998 Elsevier Science B.V.