O sistema integrado de produção: aspectos ecológicos e econômicos

Abstract

Products derived from cultivated trees are experiencing growing demand from society, which has required the productive sectors to pay attention to environmental and climate issues, and has also motivated investment and development in the basic forestry sector. In this context, the forest biomass segment is emerging as a major player in meeting energy needs, being recognized as an important renewable source and has shown interest in research and technologies capable of making production economically viable and more environmentally sustainable through studies on biomass quantification, carbon stock, CO2 equivalent stock, nutritional factors, best plantation management practices, mainly related to the harvesting system and economic feasibility studies. The objectives of this study were to quantify biomass, carbon and nutrient stocks, define nutritional export scenarios at the time of harvest, analyze the economic advantages for the producer of adopting one of the proposed scenarios and analyze the economic viability of planting five eucalyptus clones at five years of age in IPF systems in the municipality of Morrinhos - Goiás. In the study area, a livestock-forest integration system was implemented in 2018, located in the Technological Reference Unit - URT, on the campus of the Federal Institute of Goiás with 10 hectares of extension, the area is a clonal test developed by Embrapa forests, where the forest inventory was carried out in April 2023, from the same, a ranking was carried out selecting the 5 best clones from the best to the worst, the criterion used in the ranking was greater volume of wood in the stem. Five trees were selected from each clone and then felled for analysis. The clones selected were AS-028 (E. urophylla x E. grandis), GG-2808 (E. urophylla x E. grandis), AS-006 (E. urophylla - hybrid), GG-1069 (E. urophylla x E. grandis), and GG-1980 (E. urophylla x E. grandis). After selection, a rigorous cubing of the stem was carried out according to the Smalian method, followed by the collection of wood disks from all the trees in the longitudinal positions: 0, DBH, 25%, 50%, 75% and 100% of commercial height. To estimate biomass, the basic wood density of each clone was determined. To calculate the biomass of the other components, a compartmentalization model obtained from a bibliographic survey of biomass for clones at a similar age was used. The results obtained for the average accumulated biomass for the five clones studied ranged from 104,050.00 to 139,067.00 kg/ha. To obtain the carbon stock and carbon equivalent values according to the IPCC, it was necessary to multiply the biomass value obtained by the factors 0.5 and 3.67 respectively. The results obtained for the carbon stock for the five clones studied were between 52,025.00 and 69,533.70 kg/ha, while the results obtained for the CO2 equivalent stock for the five clones studied were between 190,931.75 and 255,188.67 kg/ha. To obtain the nutrient content and stock values for each clone, samples made up of branches, leaves, bark and wood from each clone studied were sent to the analysis laboratory. Nutrient contents were found in greater concentration in the leaf compartment, while the lowest concentration was found in the wood of all the clones. Nutrient stocks were higher in the wood compartment due to its high biomass for all five clones. Three nutrient export scenarios were proposed based on the harvesting system (CN1, CN2 and CN3), where CN1 represents the removal of all aboveground biomass (wood, twigs, leaves and bark), CN2 represents the removal of wood and bark, with twigs and leaves remaining in the harvesting area, and CN3 represents the removal of only wood, with twigs, leaves and bark remaining in the area. With the results of the volume of waste left on site and the nutrient stock, the expected savings in fertilizers for each scenario were calculated. The savings generated based on the scenarios were estimated at between R$ 2,055.69 and R$ 3,487.44 for scenario 2 and between R$ 2,896.67 and R$ 4,314.00 for scenario 3. For the planting feasibility analysis, each clone was treated as a project, all the amounts invested and revenues were collected and tabulated, resulting in the cash flow for each project, a Minimum Attractiveness Rate (MAR) of 6% was set, based on the cash flow the Present Value of Benefits PV(B), Present Value of Costs PV(C), Net Present Value (NPV), Annualized Net Present Value (ANNV), Internal Rate of Return (IRR) were calculated. The results obtained for all the projects based on the classic methodology (MC) were that all the projects are considered attractive (or recommendable)