Thiago Taglialegna Salles

Modelo de Clutter na modelagem de crescimento e produção de eucalipto em sistemas de integração lavoura-pecuária-floresta

The objective of this work was to define the best form of use of the Clutter model, in order to estimate growth and yield of eucalyptus clones in crop-livestock-forest integration systems. Data were collected from integration systems located in the northwest region of the state of Minas Gerais, Brazil. The data were originated from 180 continuous inventory permanent plots of 30x40 m, with three ten-plant rows and stratified random sampling of one plot per 10 ha. The average number of trees per hectare was 242. Plants with ages from 20 to 95 months were evaluated. The best functional relationships were obtained using the original Clutter model, based on the significance and on the expected signs of its estimated parameters. The Clutter model should be adjusted on its unreduced form.

Exportação brasileira de papel e celulose: sua dinâmica pela equação gravitacional

RESUMO – O Brasil figura entre os principais produtores de celulose e papel e a industria brasileira e mundialmente competitiva no setor. Com interesses voltados para este cenario, aplicou-se neste estudo a equacao de gravidade, usada para explicar de maneira empirica fluxos de comercio entre paises, com objetivo de analisar a dinâmica da exportacao de papel e de celulose pelo Brasil no periodo de 1997 a 2005. O modelo gravitacional foi adaptado e suas variaveis explicativas foram: PIB do Brasil, PIB do pais importador, PIB per capita do pais importador e distância entre o importador e o Brasil. Os resultados mostraram que a distância influenciou negativamente as exportacoes de papel, mas ao contrario do esperado, seu coeficiente associado apresentou valor positivo para a exportacao de celulose. O PIB per capta dos paises importadores teve contribuicao positiva para as exportacoes de celulose e negativa para as de papel. Tanto o PIB do Brasil, quanto o PIB dos paises importadores tiveram seus coeficientes associados apresentando valor positivo, como esperado. Concluiu-se que o modelo obteve exito na predicao dos fluxos bilaterais do comercio das commodities em analise. As exportacoes, tanto de papel quanto de celulose, foram mais sensiveis a variacoes no PIB do Brasil do que a variacoes no PIB, PIB per capita e na distância dos paises importadores. A distância influencia negativamente as exportacoes de papel, mas nao as da celulose brasileira. Palavras-chave: Exportacao de papel e celulose, Modelo gravitacional e Brasil. BRAZILIAN EXPORTS OF WOOD PULP AND PAPER: ITS DYNAMICS BY THE GRAVITATIONAL EQUATION

Fatores Impactantes no Valor Bruto da Produção de Pimenta-do-reino (Piper nigrum L.) no Pará

The aim of this paper was to quantify and analyze the changes occurred, between the years 1998 to 2012, in the gross value of production of the black pepper in the State of Pará, as well as the changes in the factors of its variation: harvested area, crop yield and price. For the analysis, it was used the geometric rate of growth, the coefficient of variation and the “shift-share” model applied to the culture’s data. Overall, the gross value of production increased in the studied period, passing through an initial period of decline, with recovery of growth in 2006. The harvested area and the selling price increased between the period of 1998 to 2012, while the crop yield decreased. The price showed greater oscillation among the studied factors and had the highest impact in the gross value of production. The productivity proved to be more stable. Increases in harvested area and especially in productivity were considered of interest so the culture of black pepper can grow in market value.

COMPARISON OF PROCEDURES FOR IMMEDIATE CHEMICAL ANALYSIS OF CHARCOAL

The climate change, the quest for sustainability and the strong environmental pressures for alternatives to traditional fossil fuels have increased the interest in the search and use of renewable energy sources. Among them stands out the biomass of charcoal coming from renewable forests, widely used as a thermal reductant in the steel industry in the detriment of the use of mineral coal coke. This study aimed to compare different operating procedures of immediate chemical analysis of charcoal. Seven essays to immediate chemical analysis were compared, spread between procedures performed by Brazilian companies and laboratories, the test described by NBR 8112 and one realized with a thermogravimetric analyzer (TGA) using the parameters of the NBR 8112. There were significant differences in the volatiles matter content and consequently in the fixed carbon contents found. The differences between the procedures and the NBR 8112 were caused by an excess burning time, a mass sample above or below the standard or inappropriate container used for burning. It observed that the TGA appraisal of the volatiles content must be carried out with a burning time equal to 2 minutes to obtain results similar to those of the NBR 8112 norm. Moreover, the ash content values were statistically identical and the particles size did not influence the differences between means.

Análise econômica de sistemas agroflorestais via uso de equações diferenciais

RESUMO – A aplicacao de diferentes tecnicas de analise economica em sistemas agroflorestais e de grande importância para suporte as tomadas de decisoes. Assim, testou-se um modelo de equacao diferencial como metodologia de analise da viabilidade economica de um sistema agroflorestal (SAF), observando se havia influencia das receitas intermediarias de uma cultura agricola no periodo de rotacao da cultura arborea, em dois horizontes de planejamento: um unico corte e varios cortes, executando-se a reforma ou a substituicao apos o corte do alto fuste. Concluiu-se que, para horizonte de planejamento de um corte, variacoes na receita da cultura agricola nao afetarao a idade otima de corte. Entretanto, variacoes na receita agricola implicarao em variacoes inversamente proporcionais na idade otima de corte quando se planeja um horizonte com varios cortes das arvores, ou seja, devido ao lucro com o cultivo agricola, e economicamente viavel antecipar o corte da madeira e realizar a reforma do plantio. Palavras-chave: Economia florestal; Rotacao florestal; Agrossilvicultura. ECONOMIC ANALYSIS OF THE AGROFORESTRY SYSTEMS BY USING DIFFERENTIAL EQUATIONS