Effect of spacing and age on nitrogen and phosphorus distribution in biomass of Eucalyptus camaldulensis, Eucalyptus pellita and Eucalyptus urophylla plantations in southeastern Brazil

The nitrogen and phosphorus accumulation in different tree parts (including root systems) of Eucalyptus camaldulensis Dehnh., Eucalyptus urophylla Blake and Eucalyptus pellita F. Muell. planted at three spacings (3 m x 1.5 m, 3 m x 3 m and 4 m x 3 m) and at three ages (15, 31 and 41 months) were evaluated in the savanna region of central Minas Gerais state in southeastern Brazil. A series of equations were produced to estimate per-tree nitrogen and phosphorus from age, spacing, diameter and height, and per-hectare nitrogen and phosphorus using age, spacing and a tally of tree diameters and heights. The highest N and P concentrations were observed in foliage (15-23 g N kg(-1) and 0.8-1.1 g P kg(-1)) and the lowest N concentration in bolewood (2.4-4.1 g N kg(-1)), while the lowest P concentration was observed in the taproot (0.16-0.29 g P kg(-1)). Total biomass N at age 41 months was greatest in E. urophylla (378-457 kg N ha(-1)), lower in E. pellita (238-326 kg N ha(-1)) and lowest in E. camaldulensis stands (204-240 kg N ha(-1)), depending on spacing. Total biomass P at age 41 months was also greatest in E. urophylla (16.6-21.8 kg P ha(-1)), and about equal in E. pellita (10.4-12.8 P ha(-1)) and E. camaldulensis stands (10.4-12.2 kg P ha(-1)), depending on spacing. As age and spacing increased, individual stems increased in diameter and total N and P, but the relationship between total N and P pools and age and spacing was more variable. (C) 2000 Elsevier Science B.V. All rights reserved.