The objective of this study was to estimate the biomass, nutrient stocks, and simulate the export of nutrients, in different genotypes of Eucalyptus. The experiment was conducted in São Gabriel, RS, Brazil, in 43-month-old stands. The selected trees were fractionated into leaves, branches, stembark and stemwood. An estimate of nutrient exports by biomass was calculated for three scenarios. The amount of total biomass ranged from 33.68 to 84.00 Mg ha -1 , with the highest production being E. uroglobulus, and E. dunnii the lowest. The tree canopy accumulated between 47% and 65% of the total macronutrients and 46% to 67% of the total micronutrients (E. benthamii (P2) and E. urograndis). The highest amount of nutrients exported with biomass harvesting, for the first and second scenario (harvesting the stemwood and harvesting the stemwood with stembark), occurred in E. uroglobulus (N, K, and S), E. urograndis (P, Mg, and Cu) and E. saligna (Fe, Zn, and B). For the third scenario (stem and canopy), the highest nutrient exportation occurred in E. urograndis, except for S, where the highest removal occurred in E. uroglobulus. The harvesting of only the stemwood resulted in the removal of the least nutrients from the system, independent of the genotypes.Produção de biomassa e conteúdo de nutrientes em diferentes genótipos de Eucalyptus no Pampa gaúcho RESUMO: O objetivo deste trabalho foi estimar a biomassa, o estoque de nutrientes e simular a exportação de nutrientes em diferentes genótipos de Eucalyptus. O experimento foi conduzido em São Gabriel, RS, em povoamentos com 43 meses de idade. As árvores selecionadas foram fracionadas em folhas, galhos, casca do fuste e madeira do fuste. A estimativa da exportação de nutrientes por biomassa foi calculada para três cenários. A quantidade de biomassa total variou de 33,68 a 84,00 Mg ha -1 , destacando-se o E. uroglobulus com a maior produção e o E. dunnii com a menor. A copa das árvores acumulou entre 47% e 65% do total de macronutrientes e 46% a 67% do total de micronutrientes (E. benthamii (P2) e E. urograndis). Para o primeiro e segundo cenário (colheita da madeira do fuste e colheita da madeira do fuste com casca), a maior quantidade de nutrientes exportados ocorreu no E. uroglobulus (N, K e S), E. urograndis (P, Mg e Cu) e E. saligna (Fe, Zn e B). Para o terceiro cenário (fuste e copa), a maior exportação de nutrientes ocorreu no E. urograndis, com exceção de S, onde a maior remoção ocorreu no E. uroglobulus. A colheita apenas da madeira do fuste apresentou a menor remoção de nutrientes do sistema, independente do genótipo.Palavras-chave: clones de Eucalyptus; nutrição de florestas; silvicultura; sustentabilidade Biomass production and nutrient content in different Eucalyptus genotypes in Pampa Gaúcho, Brazil Rev. Bras.

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.