Stem profile modeling is crucial in the forestry sector, particularly for commercially valuable species like teak (Tectona grandis Linn F.), whose value depends on its stem dimensions, heartwood proportion, and age. We proposed a nonlinear mixed-effect model to describe the evolution of the stem and heartwood profiles of clonal teak trees with ages between 4 and 12 years in the Brazilian Amazon. Tapering models were used to estimate the bark, bark-free, and heartwood diameters. Dummy variables were included in each tapering model to estimate each type of diameter and enable compatibility. We used mixed models with age as a random effect in order to improve the accuracy. The Demaerschalk model provided the most accurate and compatible estimates for all three types of stem diameter. Also, age as a random effect significantly improved the model’s accuracy by 7.2%. We observed a progressive increase in the heartwood proportion (14% to 34%) with advancing age, while the proportions of bark (23% to 20%) and sapwood (63% to 45%) showed inverse behavior. The growth rate of the heartwood differed from that of the bark volume, emphasizing the importance of considering the age of heartwood maximization when determining the cutting cycle of the species.

Brazil has a vast reserve of natural forests that belong to the state; hence, the state is responsible for supplying native wood to the market. However, the management in public forests has only begun recently; thus, much research is needed to know about its profitability. This study analyzed the financial feasibility of public forest management by addressing the following aspects: state concession, federal concession, and community forest management. We used the Net Present Value, Annual Equivalent Value, and Average Cost of Production methods to assess financial feasibility and applied the Monte Carlo simulation to estimate the probability of occurrence of NPV values. Community forest management showed profitability and a low occurrence of positive NPV values. The initial subsidies and the absence of royalty payments contributed to their good financial performance. The state and federal forest concessions showed financial unfeasibility and a low probability of profitability, which were justified by a low harvested volume of forest management, a high number of hollow individuals with small dimensions, poor volume estimates, and a high occurrence of species with low commercial values. Financial viability is a critical aspect of public forest management, and the achievement of good results depends on the consideration of several factors and aspects of public forests. Characteristics such as species composition, the distance between the managed areas, and the place of consumption must be considered. Areas that are not financially viable in the current period can be considered for future management and maintenance.

Neste estudo é testada a viabilidade econômica de doze alternativas de espaçamentos com Eucalyptus grandis para lenha. A produção de madeira foi avaliada aos oito anos e os preços das atividades obtidos com coeficientes da região. Nas receitas foi considerado o preço da madeira com casca em pé no mercado. A avaliação deu-se por cinco critérios: VPL, B/C, TIR, VET e CMPr. Considerando a taxa de desconto, todos os projetos mostraram-se viáveis economicamente. A maior produção ocorreu nos plantios mais densos, contudo, não foram os melhores pelos critérios econômicos, devido à maior imobilização de capital para implantação. O espaçamento de 5,0 m²/planta apresentou os melhores resultados em todos os critérios, sendo a melhor alternativa de investimento para uso energético. Seguido pelo espaçamento de 7,5 m²/planta, que se mostrou promissor, pois possibilita manejar a floresta visando obter multiprodutos. As alternativas com espaço inferior a 3,75 m²/planta não são recomendadas.

The Cerrado has high plant and vertebrate diversity and is an important biome for conserving species and provisioning ecosystem services. Volume equations in this biome are scarce because of their size and physiognomic diversity. This study was conducted to develop specific volumetric models for the phytophysiognomies Gallery Forest, Dry Forest, Forest Savannah, and Savannah Woodland, a generic model and a model for Cerrado forest formation. Twelve 10 m × 10 m (100 m²) (National Forest Inventory) plots were used for each phytophysiognomy at different sites (regions) of the Federal District (FD) where trees had a diameter at breast height (DBH; 1.30 m) ≥5 cm in forest formations and a diameter at base height (Db; 0.30 m) ≥5 cm in savanna formations. Their diameters and heights were measured, they were cut and cubed, and the volume of each tree was obtained according to the Smalian methodology. Linear and nonlinear models were adjusted. Criteria for the selection of models were determined using correlation coefficients, the standard error of the estimates, and a graphical analysis of the residues. They were later validated by the chi-square test. The resultant models indicated that fit by specific phytophysiognomy was ideal; however, the generic and forest formation models exhibited similar performance to specific models and could be used in extensive areas of the Cerrado, where they represent a high potential for generalization. To further increase our understanding, similar research is recommended for the development of specific and generic models of the total volume in Cerrado areas.

O trabalho teve como objetivo geral avaliar a demanda de madeira para as serrarias no Vale do Rio Pardo e, ainda, analisar a viabilidade financeira de implantar uma base florestal que supra a capacidade ociosa de processamento dessa região. O estudo foi desenvolvido na área central do Rio Grande do Sul, abrangendo 13 municípios que compõem a Bacia Hidrográfica do Rio Pardo. Para a obtenção dos dados foram realizadas entrevistas semiestruturadas com proprietários de serrarias da região. Essas foram avaliadas quanto ao seu consumo e capacidade instalada, que, respectivamente, foram de 7.005 m³.mês-1 e 12.330 m³.mês-1, apresentando uma capacidade ociosa na ordem de 63.900 m³.ano-1. O abastecimento de 30.336 m³.ano-1 ocorre através de fornecedores de fora da região. Com isso, verificou-se a necessidade de 1.836 ha para suprir a demanda anual destas serrarias. A substituição da importação de matéria-prima e o incremento da capacidade ociosa seriam responsáveis por gerar 55 empregos nas atividades de produção florestal e 471 empregos na indústria. Conforme análise financeira pelo Método de Monte Carlo, a receita anual gerada pelo empreendimento seria na ordem de R$ 1.756.347,00, correspondente a uma área de colheita estimada em 122,40 ha, distribuída nos municípios da região.

In the Neotropical Savanna domain, few equations are available for estimating biomass stocks in Cerrado sensu stricto (CSS), despite the importance of such tools for estimating carbon stocks, understanding ecosystem functioning, and supporting conservation actions. We conducted forest inventories in 40 temporary 1000 m² plots in southeastern Brazil to estimate total and compartmental biomass stocks and to model biomass using structural and edaphic predictors. Total biomass (TB) included aboveground woody biomass (AGWB), necromass, litter, and belowground biomass (BGB). AGWB was estimated for trees with basal diameter ≥ 5 cm using a previously fitted regional equation. Root biomass was sampled using a 1 m³ trench excavated at a single point adjacent to each plot. Necromass was quantified using the line-intersect method along a 50 m transect, considering debris with diameter ≥ 3 cm. Litter was sampled using a 0.25 m² frame placed at the center of each plot. Biomass was modeled on an area basis using a hierarchical approach for TB, total tree biomass (TTB = AGWB + BGB), and AGWB. Mean stocks (Mg ha⁻¹ ± s.d.) were 45.24 ± 17.32 (TB), 20.47 ± 11.26 (AGWB), 18.47 ± 10.88 (BGB), 5.49 ± 4.18 (litter), and 0.81 ± 1.62 (necromass). Models selected using the Akaike Information Criterion (AIC) and validated by repeated k-fold cross-validation achieved rŷy = 0.76, 0.72, and 0.94 and RMSE = 24.40%, 27.06%, and 18.10% for TB, TTB, and AGWB. As the equations were calibrated for CSS under the environmental conditions of the Brazilian semiarid region, their transferability to other Cerrado regions should be considered with caution. The inclusion of soil variables (e.g., Al, Mg, and sand) improved predictions, reducing relative costs and taxonomic dependence, while incorporating nutritional adaptations to the acidic soils characteristic of the biome.