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It is well recognized that commercial beef cattle production systems have a major impact on climate change, mainly due to the emission of enteric methane (CH4). The objective of this research was to evaluate if integrating animal + pasture + timber production in silvopastoral systems (SPS) would help neutralize the impact of enteric CH4 emission by facilitating carbon storage as soil organic carbon (SOC). This paper reports a study conducted in Brazil with a herd of 150 cows in 100 ha of Urochloa brizantha with Eucalyptus urograndis, on four tree configurations: SPS 1-clone GG-100 at 2 × 3 × 15 m spacing; SPS 2-clone i-144 at 2 × 3 × 15 m; SPS 3-clone GG-100 at 3 × 15 m; and SPS 4-clone i-144 at 3 × 15 m. Based on data collected through eight consecutive years, the gas balance was estimated. For all SPS treatments average, the carbon dioxide equivalent (CO2e) of additional C stock exceeded the emissions. Considering only C sequestration from trees, the average CO2e sequestration was − 26.27 Mg·CO2e ha−1, while the average emissions of CO2 e was 23.54 Mg·CO2e ha−1 for enteric CH4 + pasture + tree, giving a net balance of − 2.73 Mg·CO2e ha−1. The “loss” of CO2e analyzed was compensated by the soil C sequestration in long-lived SOC pools, enhancing the resilience of farming systems by increasing soil organic matter and soil fertility capacity, mitigating greenhouse gas emissions, therefore, providing benefits in livestock production and for environmental remediation.

Agroforestry systems with eucalyptus prevail in Central and Southeast Brazil, and little information is available about systems using native trees. The aim of the present study was to evaluate the development of seven native tree species grown under two agroforestry systems. The experiment was conducted starting in 2007 in 12-hectare area in the municipality of São Carlos, São Paulo state, Brazil. The tree species planted in the two systems (a silvopastoral system and an agrisilvicultural system) were: 'capixingui' (Croton floribundus) and 'mutambo' (Guazuma ulmifolia) (tutors), 'jequitibá-branco' (Cariniana estrellensis), 'canafistula' (Peltophorum dubium) and 'ipê felpudo' (Zeyheria tuberculosa) (timber trees), and 'angico-branco' (Anadenanthera colubrina) and 'pau-jacaré' (Piptadenia gonoacantha) (N-fixing trees). Data were collected for 48 months. The results show differences among tree development, which was evaluated as growth in height and diameter, as well as sensitivity to insect and disease damage. The overall results show that the agrisilvicultural system allowed better tree development. The species with best performance in the two systems were capixingui, mutambo and canafístula. Ipê-felpudo and jequitibá-branco showed the worst results. The high variability among individuals of the same species indicates the possibility of high production advances with selective breeding of these species.

The objective of this study was to select allometric models to estimate total and pooled aboveground biomass of 4.5-year-old capixingui trees established in an agrisilvicultural system. Aboveground biomass distribution of capixingui was also evaluated. Single- (diameter at breast height [DBH] or crown diameter or stem diameter as the independent variable) and double-entry (DBH or crown diameter or stem diameter and total height as independent variables) models were studied. The estimated total biomass was 17.3 t.ha-1, corresponding to 86.6 kg per tree. All models showed a good fit to the data (R2ad > 0.85) for bole, branches, and total biomass. DBH-based models presented the best residual distribution. Model lnW = b0 + b1* lnDBH can be recommended for aboveground biomass estimation. Lower coefficients were obtained for leaves (R2ad > 82%). Biomass distribution followed the order: bole>branches>leaves. Bole biomass percentage decreased with increasing DBH of the trees, whereas branch biomass increased. RESUMO O objetivo deste estudo foi selecionar equações alométricas para predição da biomassa aérea total e nos compartimentos aéreos de capixingui com 4,5 anos estabelecidas em um sistema silviagrícola. Foram tomadas medidas dendrométricas e utilizou-se o método destrutivo para a estimação da biomassa, com a separação dos componentes em tronco, galhos e folhas. Foram ajustados e comparados quatro modelos alométricos, sendo dois de simples entrada e dois de dupla entrada. Como variáveis preditoras foram considerados o diâmetro à altura do peito (DAP), diâmetro de colo (D colo), diâmetro de copa (Dc) e altura total (H). A biomassa total estimada foi de 17,3 t.ha-1, equivalente a 86,6 kg por árvore. Todos os modelos apresentaram ajustes satisfatórios (R2aj>0,85) para tronco, galhos e biomassa total. As equações para biomassa total que tiveram como variávelpreditora o DAP apresentaram as melhores distribuições de resíduos. O modelo lnW=b0+b1*lnDAP pode ser recomendado para estimativa de biomassa aérea. Para folhas, os coeficientes foram menores (R2aj>82%). A distribuição da biomassa nos componentes seguiu a ordem: tronco>galhos>folhas. A percentagem de biomassa no tronco decresceu com o aumento do DAP das árvores enquanto que a biomassa nos galhos aumentou.

Neste trabalho estudou-se a viabilidade econômica de um plantio de teca (Tectona grandis L.f.) submetido a desbastes. Foram utilizados os seguintes critérios de análise econômica de projetos: valor presente líquido, benefício (custo) periódico equivalente, taxa interna de retorno e valor esperado da terra. A taxa de desconto utilizada foi de 10% a.a. Os indicadores demonstraram a viabilidade econômica do plantio da teca, conforme as condições estabelecidas na análise. O plantio será inviável se houver redução maior que 25% nas receitas ou aumento superior a 35% nos custos, sendo, portanto, mais sensível às variações na redução de receitas que às variações no aumento de custos. This work evaluated the economic viability of a teak plantation (Tectona grandis L.f. ) submitted to thinning. The following economic criteria of project analysis were applied: Net Present Value, Equivalent Annual Benefit (Cost), Internal Return Rate and Land Expected Value. The discount rate applied was 10% a year. The indicators showed the economic viability of the teak plantation, under the conditions established in the analysis. The plantation will not be viable by reducing 25% of the revenues or increasing 35% of the costs, being more sensitive to the variations in income decrease than to variations in cost increase.

O objetivo deste trabalho foi avaliar a viabilidade econômica de um sistema agrossilvipastoril, desenvolvido para áreas montanhosas da Zona da Mata mineira, Brasil, bem como comparar diferentes alternativas de comercialização da madeira (Eucalyptus grandis and Acacia mangium) do segundo desbaste. Os dados foram obtidos em um sistema agrossilvipastoril com dez anos de idade, implantado em área de quatro hectares, no Campo Experimental de Coronel Pacheco, pertencente à Embrapa Gado de Leite. Como critérios de avaliação para a análise de viabilidade econômica, foram utilizados os métodos do valor presente líquido e o da taxa interna de retorno, ambos calculados para a taxa de juros de 6%. Apesar da pouca diferença, a agregação de valor ao produto florestal aumentou a atratividade do sistema. Considerada isoladamente, a atividade agrícola se mostrou inviável, enquanto a silvicultura e a atividade pecuária foram independentemente viáveis. O sistema estudado parece ser igualmente tolerante a variações nos preços do produto florestal e do produto pecuário, assim como fortemente tolerante a variações nos custos de produção. The objective of this work was to evaluate the economic viability of an agrosilvipastoral system developed for Zona da Mata mountainous areas in Minas Gerais state, Brazil, as well as to compare different options for wood (Eucalyptus grandis and Acacia mangium) commercialization of the second thinning. The data were obtained from a 10 year-old agrosilvipastoral system established in four hectares at Embrapa Gado de Leite station in Coronel Pacheco, MG, Brazil. As evaluation criteria for the economic viability analysis, the adopted methods were the net present value (NPV) and the internal rate of return (IRR), both calculated at 6% interest rate. Despite the small difference, adding value to forest products increased the attractiveness of the proposed system. Considered separately, the agricultural activity was impracticable, whereas the forestry and livestock activities were independently viable. The studied system seems to be equally tolerant to price variations for forest and livestock products, as well as strongly tolerant to variations in production costs.

Dois experimentos foram conduzidos com o objetivo de avaliar a tolerância de plantas mogno-africano (Khaya ivorensis) e cedro-australiano (Toona ciliata var. australis) a herbicidas. O delineamento experimental foi inteiramente casualizado, com quatro repetições. Tratamentos: i) testemunha sem aplicação, ii) imazapyr (25 g i.a. ha-1), iii) oxyfluorfen (360 g i.a. ha-1), iv) oxyfluorfen (720 g i.a. ha-1), v) isoxaflutole (75 g i.a. ha-1), vi) isoxaflutole (112,5 g i.a. ha-1), vii) chlorimuron-ethyl (7,5 g i.a. ha-1) + 0,05% v/v de óleo mineral, viii) chlorimuron-ethyl (12,5 g i.a. ha-1) + 0,05% v/v de óleo mineral, ix) imazethapyr (100 g i.a. ha-1) e x) nicosulfuron (40 g i.a. ha-1). Para o mogno africano, os herbicidas imazapyr (25 g i.a. ha-1), oxyfluorfen (360 g i.a. ha-1) e chlorimuron-ethyl (7,5 e 12,5 g i.a. ha-1) proporcionaram sintomas leves de fitotoxicidade. O oxyfluorfen (720 g i.a. ha-1), o imazethapyr e o nicosulfuron foram moderadamente fitotóxicos e o isoxaflutole (75 e 112,5 g i.a. ha-1) foi o herbicida mais fitotóxico. Para o cedro australiano, o herbicida imazapyr (25 g i.a. ha-1) proporcionou os menores níveis de injúria. O oxyfluorfen, o isoxaflutole, o chlorimuron-ethyl, o imazethapyr e o nicosulfuron proporcionaram altos níveis de fitotoxicidade.Palavras-chave: Mogno africano; cedro australiano; plantas daninhas; seletividade. AbstractTolerance of Khaya ivorensis and Toona ciliata to herbicides. We conducted two experiments to evaluate the plant tolerance of African mahogany (Khaya ivorensis) and Australian cedar (Toona ciliata var. australis) to herbicides. The experimental arrangement was a completely randomized design, with four replications. The treatments were as follows: i) untreated control, ii) imazapyr (25 g ai ha-1), iii) oxyfluorfen (360 g ai ha-1), iv) oxyfluorfen (720 g ai ha-1), v) isoxaflutole (75g ai ha-1), vi) isoxaflutole (112.5 g ai ha-1), vii) chlorimuron-ethyl (7.5 g ai ha-1) + 0.05% v / v mineral oil, viii) chlorimuron-ethyl (12.5 g ai ha-1) + 0.05% v / v mineral oil, ix) imazethapyr (100 g ai ha-1), and x) nicosulfuron (40 g ai ha-1). For the African mahogany, imazapyr (25 g ai ha-1), oxyfluorfen (360 g ai ha-1) and chlorimuron-ethyl (7.5 and 12.5 g ai ha-1), showed mild symptoms of phytotoxicity. The oxyfluorfen (720 g ai ha-1), imazethapyr and nicosulfuron were moderately phytotoxics, and isoxaflutole (75 and 112.5 g ai ha-1) was the most phytotoxic herbicide. For Australian cedar, imazapyr (25 g ai ha-1) caused low levels of injury. Oxyfluorfen, isoxaflutole, chlorimuron-ethyl, imazethapyr and nicosulfuron were the most phytotoxic herbicides. Keywords: African mahogany; Australian cedar; weeds; selectivity.

O objetivo deste trabalho foi selecionar modelos alométricos para estimativa de altura, volume e afilamento do tronco de duas espécies florestais estabelecidas em um sistema silvipastoril com 10 anos de idade. Para a variável volume, foram testados modelos de simples e dupla entrada e para o afilamento do tronco foram testados modelos segmentados e não segmentados. Para estimativa da altura das árvores de eucalipto, foi selecionado o modelo semilogarítmico e para a acácia o modelo de melhor desempenho foi o exponencial. Entre os modelos volumétricos, aqueles de dupla entrada apresentaram melhores ajustes, sendo que o modelo de Schumacher & Hall se destacou com estatísticas ligeiramente superiores aos demais. Para o afilamento de tronco, os modelos segmentados apresentaram melhor desempenho. Para árvores de eucalipto, o modelo de Max & Burkhart se mostrou mais adequado, e para acácia, o modelo de Parresol foi o que apresentou o melhor ajuste. De forma geral, os modelos se ajustaram melhor aos dados das árvores de eucalipto.Palavras-chave: Agrossilvicultura; modelagem; programa ABC. AbstractHeight, volume and taper equations for eucalipt and acacia mangium established in a silvopastoral system. The objective of this work was to select allometric models for height, volume and taper estimation of two forestry species established in a ten years old silvopastoral system. Single (breast height diameter as the independent variable) and double entry (breast height diameter and total height as independent variables) models were evaluated for the volume estimation. We evaluated segmented and non-segmented models for the taper equations. The semilogaritmic model and the exponential model fitted better for the estimation of eucalyptus and acacia trees height, respectively. In general, the double entry volumetric models presented the best adjustments and Schumacher & Hall`s model presented slightly higher statistics among the models. In the case of taper models, we observed that the segmented models fitted better to the data for both species. Max & Burkhar´s model and the Parresol´s model were selected for eucalyptus trees and acacia trees, respectively. In general, all tested models fitted better to eucalyptus trees.Keywords: Agroforestry; Modeling; Eucalyptus; Acacia.