Estimation of nutrient export in eucalypts genotypes under different harvest intensities in Southern Brazil

Abstract

The study of the nutrients removed with forest harvesting is presented as an essential fator favoring the sustainable use of forest stands. The research was carried out in an experimental area in Horto Florestal Terra Dura in the municipality of Eldorado do Sul, RS, Brazil, where six Eucalyptus clones were planted. Based on the nutrient stock of each biomass component, the simulation of nutrient removal through biomass harvesting was calculated for three scenarios: (1) harvesting of stemwood, (2) harvesting of stemwood with stembark, and (3) harvesting of all aboveground biomass. In the first scenario, the highest amount of nutrients exported with biomass harvest occurred in the Eucalyptus hybrids E. urophylla x E. globulus (N, K, S, and Fe) and E. urophylla x E. grandis (Ca, B, Cu, and Zn). In the second scenario, the highest nutrient exportation occurred in E. benthamii (Provenance 1) (N, P, Ca, Mn, and B) and hybrid E. urophylla x E. globulus (K, S, and Fe). In the third scenario, the highest nutrient exportation occurred in E. benthamii (Provenance 1) (P, Ca, B, Mn, and Zn), E. grandis (Mg and Cu), and hybrid E. urophylla x E. globulus (N, K, S, and Fe). Harvesting of all aboveground biomass was the most aggressive scenario, showing the highest export of nutrients. However, for reducing the nutritional impact of biomass harvesting, the best scenario was the one in which only stemwood was harvested.