Nutrients and biomass in <em>Eucalyptus urophylla x Eucalyptus globulus</em> stand in Eldorado do Sul - RS

Abstract

Nutrients and biomass estimation in eucalyptus stands are important for to obtain techniques and practices definition to keep the soil productive capacity. With this, the study had objective estimated aboveground biomass and nutrients contend within in Eucalyptus urophylla x Eucalyptus globulus 10 years-old stand, located in Eldorado do Sul - RS. Allocated four experimental plots (35 m x 20 m) where the forestry inventory was conducted and the definition of diametric classes stand (five classes). In each diametric class were harvested three trees for biomass and nutrients quantification. Understory biomass and nutrients was quantified in five plots of 25 m² each. Eucalyptus biomass was estimated using regression equations by Stepwise procedure. Equations obtained with regression analysis showed good prediction of the variables due to the high determination coefficient and low standard error estimates. Eucalyptus biomass was allocated predominantly to stem (Wood + bark) with 93.7%. These same components, also had the largest nutrients stock. Understory biomass comprises a small aboveground fraction (1.4%), but had 7.0 and 8.6% of nitrogen and sulfur from the total stock . Biomass components had different chemical composition, being generally higher in leaves and bark and smaller in wood and branches biomass.