ABOVEGROUND BIOMASS PRODUCTION AND NUTRIENT ACCUMULATION IN A FIVE YEAR OLD EUCALYPTUS GRANDIS AND E. UROPHYLLA PLANTATION

Abstract

Nutrient concentrations in biomass components may vary with the component considered, plantation age and genetic material and its measurement is important to understand forestry nutrient management. Due to it, aboveground biomass production and nutrient accumulation and its potential removal through thinning in two species of Eucalyptus with five-year-old were evaluated in the southern of Brazil. Treatments were arranged in a randomized block design with three replications in a 2 x 4 factorial scheme, being 2 species (E. grandis and E. urophylla) and four diametric classes (C1: 3.0 - 8.8; C2: 8.9 - 14.7; C3: 14.8 - 20.6; C4: 20.7 -26.5 cm). Average annual accumulation of dry matter in both species was of 16.9 Mg ha-1. Biomass was mainly allocated in the stem (wood and bark). Trees’ canopy (branches and leaves) represent the smallest fractions, with only 14,3% of the total biomass. E. grandis showed highest values \u200b\u200bof wood and leaf compartments. The highest content of N and K were found on the leaves, with N levels of 33.2 and 30.5 g.Kg-1 respectively to E. grandis and E. urophylla. Trees bark represent an important Ca and Mg reserve to the development of the plant, with values \u200b\u200bof 18.02 and 3.24 g.kg-1 respectively. The mean concentration of Ca, N, K, Mg and P in the total biomass of the two species was of 528, 305, 200, 128 and 30 kg ha-1.