Evaluación productiva y ambiental de un sistema silvopastoril de Eucalyptus grandis con destino a madera sólida

In a pastoral-driven nation such as Uruguay, the interrogation of greenhouse gas emissions emanating from the livestock sector has instigated profound consternation. In this context, it is crucial to assess the carbon balance and financial viability of a system that integrates forestry and agricultural production, such as silvopastoral systems. Through a case study in the central-southern region of the country, the carbon quantity in an 11-year-old Eucalyptus grandis plantation was determined. The plantation had a teorical planting density of 625 trees/ha and underwent various silvicultural treatments to achieve a final population of 154 trees/ha pruned up to 6 m in height. Eleven permanent plots were established in two strata (Silvo Norte and Silvo Sur), where two inventories were conducted. For each tree, height and diameter at breast height were measured, and subsequently, basal area and individual volume were calculated to obtain these parameters per hectare. Samples were taken from three trees in each plot, representing three diameter classes, processed in the laboratory for wood density and carbon content using spectrophotometry. The results reveal a superior performance of Silvo Norte compared to Silvo Sur, with an average carbon percentage in the stem and bark of 40,67%, over a volume of 100,5 m³/ha (9,28 m³/ha/year). This translates to an annualized capture until 2023 of 12,2 tons/ha/year of CO₂ equivalent. Contrasting this capture with livestock emissions calculated from IPCC equations (Hongmin et al., 2006) estimates a carbon balance of -5,49 tons CO₂e/ha/year in the entirety of the silvopastoral system. These results validate the carbon sequestration potential in an integrated livestock and forestry system. This enhances the reliability of a potential carbon credit system. Regarding the financial analysis, the system yielded a Net Present Value of 210.415 U$D, considering a 7% opportunity cost, proving to be economically viable. Additionally, the calculated Internal Rate of Return was 9,07%. An analysis of the impact of carbon credit sales on the project's viability was also conducted, improving the values mentioned above. The obtained results demonstrate the environmental sustainability and economic viability of the system.