Elton da Silva Leite

Carrying out an assertive planning in logistics and forest harvesting is essential to reduce the operational costs, as well as guaranteeing a constant supply of wood for the manufacturing unit, without compromising the integrity of the fleet of machinery in the field. This study addressed the analysis of the productive capacity of two important wood harvesting machines, the Feller-Buncher, and the Harvester, with an objective to propose a technical modeling to optimize the logistics associated with these machines. Eight machines were analyzed in planted forests with different productivity (0.08 to 0.58 m³/tree). Machinery productivity was also evaluated for each forest condition. Regression analysis, means tests, and statistical inferences were carried out to present the results. The relationship between machinery productivity and forest productivity obtained through regression analysis was explained with up to 97% accuracy. The productivity curves indicated stabilization with the increase of the mean individual volume per tree (MIV). The forest being harvesting machines evaluated showed a reduction in cost per cubic meter harvested, as forest productivity increased. The productive capacity of the harvester dedicated exclusively to processing, although superior, presents a disadvantage in practical terms, mainly due to the requirement for a new machine in the felling process, therefore increasing the production cost.

The objective of this study was to evaluate the influence of the mean individual volume per tree (MIV) on the productivity of forwarder machines and the production cost in eucalyptus plantations located in southern Bahia, Brazil. MIV positively influenced the productivity and production costs, promoting a more attractive cost in the latter when the individual volume per tree increased. The machine’s productivity for MIV of 0.13 m³ was 42.06 cubic meters per effective working hour (m³Ewh⁻¹), while the productivity for the MIV of 0.58 m³ reached 60.97 m³Ewh⁻¹, corresponding to an increase of 42.59% between the minimum and maximum MIV classes. The extracted cost (m³) decreased by 30.12% from USD 2.49 to 1.74, respectively, when comparing the minimum and maximum MIV classes. The coefficient of determination obtained in the forwarder productivity modeling was significant (R² = 92%), indicating the machine’s productivity can be explained by the mean individual volume per tree. The highest forwarder yields in the highest average volume per tree (MIV) classes provided better energy efficiency indices for the machine; that is to say, when the forwarder became more productive, the ratio between fuel consumption per cubic meter of timber harvested decreased, providing better performance for the respective index. There was a difference in extraction costs of USD 147.83 per hectare between the lowest and highest productivity forests (MIV varying from 0.15 to 0.58). The mechanical availability and mean operational efficiency of all forwarders evaluated were above 80%, which contributed to effective machine productivity performance. Maintenance and repairs represented the largest portion of operational costs (33.59%), followed by labor (22.49%), depreciation (14.33%), and fuel (10.11%).

The objective of this study was to assess the performance of a feller buncher as a function of forest yields. The feller buncher productivity and production costs were evaluated in a eucalyptus forest with different mean tree volume (MTV) classes. The technical analysis included time and motion study, productivity, mechanical availability, and operational efficiency. The economic analysis was based on fixed and variable costs, which resulted in the feller buncher's total operating cost. Production costs were calculated by the ratio of operating costs to wood volume harvested per working hour, which varied according to the forest yield levels (low, medium, and high) determined based on MTV classes. The results showed a total operating cost of US$157.76 h-1 for the feller buncher, 83.52% attributed to variable costs. The highest operational performance and, consequently, lower production cost were found for the highest MTV, with a tendency for productivity stabilization as the forest yield increases. The time and motion study of the feller buncher operating cycle for the three forest yield levels showed a statistically significant difference by Tukey’s test (5% significance). A significant difference was found in the tree felling and bunching phase among the three forest yield levels, as the feller buncher operating time in low-yield forests was 46.59% greater than that in high-yield forests.

Embora avanços tecnológicos tenham ocorrido no setor florestal brasileiro, ainda não há uma padronização quanto à quantidade de água a aplicar nas diferentes etapas de desenvolvimento das plantas, e de doses de condicionadores de umidade do solo, visando a redução do déficit hídrico em solos sob cultivo do Eucalyptus urograndis. Diante disso, objetivou-se avaliar o uso do hidrogel em Eucalyptus urograndis associado a níveis de umidade do Latossolo Amarelo distrocoeso. O estudo foi conduzido em casa de vegetação da Universidade Federal do Recôncavo da Bahia. Os tratamentos foram constituídos por quatro níveis de umidade no solo (50, 75, 100 e 125%), a partir da água disponível no solo, e quatro doses de hidrogel (0; 1,5; 3,0 e 4,5 g L-1), em delineamento inteiramente casualizado em esquema fatorial 4 x 4, com 16 tratamentos e 4 repetições. As variáveis avaliadas foram: altura (H), diâmetro do caule (DC), índices de clorofila A, B e total, massa seca do caule (MSC), massa seca de folhas (MSF), massa seca da parte aérea (MSPA), massa seca de raízes (MSR), massa seca parte aérea/massa seca raiz (MSPA/MSR), massa seca total (MST) e altura/diâmetro (H/DC). O uso de hidrogel aumenta a disponibilidade de água em Latossolo Amarelo distrocoeso e reduz o efeito do déficit hídrico na cultura. A dose de 3,0 g L-1 de hidrogel proporciona melhor crescimento e produção de fitomassa do Eucalyptus urograndis, quando o nível de umidade inicial do solo está em torno da capacidade de vaso.

This research sought to identify the ideal timeframe for replacing a Harvester, used in forest harvesting, employing a comparative evaluation of different economic methods. A John Deere 1270D harvester, equipped with a 270-model head was utilized in this study. The machine’s cost per hour worked was calculated by adding fixed costs with variable costs. The methods used to determine the machine’s optimal replacement time were: the Total Average Cost (TAC) and the Equivalent Annual Cost (EAC), which consider discrete functions, and the Terminal Cycle and Constant Chain Replacement, which consider continuous functions. The four methods differed in their indication of the optimal replacement time for the harvester. Although the TAC is a simple and well-known method, it did not yield an adequate result (2 years). This is because replacing a forest machine usually occurs over a longer period of use, with current preventive and predictive maintenance routines. This discrepancy arises from the high acquisition and operational costs, as well as the method’s failure to account for the variation of capital over time (interest rate) and the revenues or production of the harvester, which significantly affects the analysis. Utilizing the discount rate, the EAC proved to be more efficient than the TAC, yielding a result that is more aligned with the reality of the forest sector (6 years). Furthermore, it is the most widespread method in machine and equipment replacement studies due to its simplicity, ease of application, and efficiency. The Chain Replacement method provided an optimal replacement time between 7 and 8 years, also consistent with the reality of companies in the forest sector engaged in forest harvesting for an extended period. Therefore, this method can be considered in decision-making as it takes into account the cost and revenue variables of the machine. Determining the useful life of a machine used in forest harvesting from an economic perspective, or the period in which it performs its activities with the lowest operational cost, is directly related to its lowest production cost. In the present study, the most suitable methods to determine the optimal replacement time for the harvester were the EAC and the Chain Replacement method.

Ergonomic analysis of pruning trees in conflict with power lines. Pruning trees in conflict with power lines is associated with several ergonomic risks due to postural issues and exposure to environmental conditions, such as noise and vibration in work activities. Additionally, there are life-threatening risks from falls or contact with power lines. The objective of this work was to apply the Ergonomic Workplace Analysis (EWA) method and assess the exposure of workers involved in pruning of trees conflicting with power lines to noise and vibration. The survey was conducted considering outsourced employees that provide services to an electric utility company in the state of Bahia, Brazil. The results obtained through EWA showed a regular risk rate, with concerning aspects, such as verbal communication (dialogue among workers regarding technical/operational issues), irregular posture of back, arms, and shoulders, high attention demand, and activity limitations. Quantitative analysis showed 84.9 dB (A-weighted) for noise and 2.440 m s^-2 for vibration, both close to the action level. The pole saw vibration reached 3.703 m s^-2, exceeding the tolerance limit. The importance of breaks, at-work exercises, and training is emphasized as ergonomic measures. A rotation system should be implemented in tree pruning activities to reduce exposure to vibration.

O sensoriamento remoto, por meio das técnicas de razão de bandas para o monitoramento nutricional de plantios clonais de eucalipto, é fundamental para garantir a sanidade, produtividade e reduzir custos de empreendimentos florestais. Objetivou-se aplicar índices de vegetação a partir de imagens de satélite de alta resolução na diagnose nutricional de macronutrientes em plantios de híbridos clonais de Eucalyptus urophylla S. T. Blake. O estudo foi realizado em 62 áreas de seis municípios do estado da Bahia sob cultivo de plantios homogêneos de eucalipto, com idades entre 1,3 e 1,8 anos. O delineamento foi inteiramente casualizado com seis tratamentos constituídos pelo regime pluviométrico (1000 a 1300 mm ano^-1 e 1300 a 1600 mm ano^-1) e tipos de solo (classe e textura). A diagnose nutricional de nitrogênio (N), fósforo (P), potássio (K), cálcio (Ca), magnésio (Mg) e enxofre (S) foi realizada a partir da análise foliar e da determinação dos índices de vegetação: índice de vegetação por diferença normalizada (NDVI), índice de diferença normalizada da água (NDWI) e índice de vegetação ajustado ao solo (SAVI). As áreas avaliadas possuem alto vigor (NDVI > 0,70) e os maiores valores foram observados nas regiões chuvosas (1300 a 1600 mm ano^-1) (médio de 0,78). O índice NDWI apresenta maior correlação para os teores médios de Ca e Mg. Os índices NDVI, NDWI e SAVI apresentam forte correlação entre si (-0,97 a 1,00) e podem auxiliar no mapeamento do vigor e consequentemente na produtividade de eucalipto.

BALANÇO DE ÁGUA EM SOLOS COESOS DE TABULEIROS COSTEIROS SOB EUCALIPTO, PASTAGEM E MATA NATIVA   EMANUELA BARBOSA SANTOS¹; LUCIANO DA SILVA SOUZA²; FELIPE GOMES FREDERICO DA SILVEIRA³; ELTON DA SILVA LEITE⁴ E EVELLYN FREIRE DA SILVA^{5   1}Engenheira Agrônoma e Doutoranda em Ciência do Solo, Departamento de Ciências do Solo, Universidade Federal do Ceará, Avenida Mister Hull, 2977, Pici, 60356-000, Fortaleza, Ceará, Brasil. E-mail: emanuelabarbbosa@gmail.com ²Engenheiro Agrônomo, Doutor em Ciência do Solo, Professor Adjunto do Centro de Ciências Agrárias, Ambientais e Biológicas da Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, 710, Centro,44.380-000, Cruz das Almas, Bahia, Brasil. E-mail: lsouza@ufrb.edu.br ³Engenheiro Agrônomo, Doutor em Produção Vegetal, Professor do Polo de Engenharia da Faculdade de Ciências e Empreendedorismo, Praça Dr. Renato Machado, 10, Centro, 44430-158, Santo Antônio de Jesus, Bahia, Brasil. E-mail: felipe.silveira@facemp.edu.br ⁴Engenheiro Florestal, Doutor em Engenharia Agrícola, Professor Associado do Centro de Ciências Agrárias, Ambientais e Biológicas da Universidade Federal do Recôncavo da Bahia, Rua Rui Barbosa, 710, Centro,44.380-000, Cruz das Almas, Bahia, Brasil. E-mail: elton@ufrb.edu.br ⁵Engenheira Agrônoma e Doutoranda em Engenharia de Sistemas Agrícolas, Departamento de Engenharia de Biossistemas, Escola Superior de Agricultura Luiz de Queiroz/USP, Avenida Pádua Dias, 11, São Dimas, 13418-900, Piracicaba, São Paulo, Brasil. E-mail: evellynagro@gmail.com     1 RESUMO   A complexidade físico-climática dos Tabuleiros Costeiros exige conhecimento sobre o regime hídrico do solo e a disponibilidade de água para as plantas de maneira crucial para o desenvolvimento sustentável nessa região do Nordeste Brasileiro. Com isso, objetivou-se com esse trabalho avaliar o regime hídrico de solos com horizonte de caráter coeso de Tabuleiros Costeiros sob eucalipto, pastagem e mata nativa, por meio do estudo do balanço de água no solo. Os solos sob mata nativa e pastagem foram classificados como ARGISSOLO AMARELO e sob eucalipto como LATOSSOLO AMARELO. As medidas foram realizadas no Município de Cruz das Almas, Bahia, durante dez meses, incluindo períodos chuvosos e secos. Foram instaladas seis sondas de TDR no solo nas profundidades de 0,10 a 1,10 m, em cada área, com medições semanais. Encontrou-se nas áreas ocupadas por pastagem e eucalipto uma maior demanda evapotranspirativa em comparação com a mata nativa, indicando que a conversão do uso da terra tem impacto direto no balanço hídrico. A evapotranspiração (ET) seguiu as variações da precipitação pluvial, sendo que a redução da ET coincidiu com o período de maior déficit hídrico no solo entre as épocas avaliadas. Palavras-chave: armazenagem de água, dinâmica de água, evapotranspiração. SANTOS, E.B; SOUZA, L. S; SILVEIRA, F. G. F; LEITE, E. S; SILVA, E.F. WATER BALANCE IN COHESIVE SOILS OF COASTAL TABLE LANDS UNDER EUCALYPTUS, PASTURE AND NATIVE FOREST 2 ABSTRACT   The physical-climatic complexity of the Coastal Table Lands requires knowledge about the soil water regime and the availability of water for plants, crucially for sustainable development in this region of Northeastern Brazil. The objective of this work was to evaluate the water regime of cohesive soils of this ecosystem under eucalyptus, pasture and native forest, through the study of soil water balance. Soils under native forest and pasture were classified as Oxisol and under eucalyptus as Ultisol. The measures were carried out in the Municipality of Cruz das Almas, Bahia, Brazil, in ten months, including rainy and dry periods. Six TDR probes were installed in the soil at depths of 0.10 to 1.10 m, in each area, with weekly measurements. It was concluded that the soil water balance showed that pasture and eucalyptus showed higher evapotranspirative demand compared to native forest, allowing to infer that more attention is needed in relation to water resources in areas where those crops are present. The evapotranspiration (ET) followed the rainfall variations, and the ET reduction coincided with the greatest water deficit in the soil between the evaluated periods. Keywords: evapotranspiration, water dynamics, water storage.

Modeling is an important tool to estimate forest production in planted areas. Although this issue has been studied worldwide, knowledge regarding volume measurement in specific locations such as Northeast Brazil is still scarce. The present study aimed to evaluated the effectiveness of artificial neural networks (ANNs) and regression analysis in estimating the timber volume of homogeneous stands of Anadantera macrocarpa, Genipa americana, and Mimosa casalpinifolia, in order to better predict the growth and production of these species. Both methods were suitable for estimating the individual volume in 7-year-old stands with different spacing. The Spurr regression model showed better statistical results and dispersion of unbiased errors for Anadantera macrocarpa and Genipa americana, whereas the Shumacher-Hall model provided more accurate volume estimates for Mimosa caesalpinifolia. The ANNs calibrated with two neurons in the middle layer exhibited the best fit for all three species. As such, artificial neural networks can be recommended to estimate the individual volumes of the species analyzed in the study area.