Renato Vinícius Oliveira Castro

Individual Growth Model for Eucalyptus Stands in Brazil Using Artificial Neural Network

This work aimed to model the growth and yield of Eucalyptus stands located in northern Brazil, at the individual tree level, by using artificial neural networks (ANNs). Data from permanent plots were used for training the neural networks to predict tree height and diameter as well as mortality probability. Once trained, the networks were evaluated using an independent data set. The first group was composed of 33 plots (11 in each productive capacity class) and was used for artificial neural network training. In five measurements, this group totaled 8,735 cases (measurements of individual trees), as each plot had 53 trees on average throughout this evaluation. The second group was composed of 30 plots (10 in each productive capacity class) and was used for model validation. This group totaled 7,756 cases. Were tested different network architectures Multilayer Perceptron (MLP). Results revealed an underestimation bias for number of surviving trees. However, estimates of diameter, height, and volume per hectare were found to be accurate. This indicates that artificial neural networks are a viable alternative to the traditional growth and yield modeling approach in the forestry sector.

Potencial energético da madeira de Eucalyptus sp. em função da idade e de diferentes materiais genéticos

The present study aimed to determine the influence of age and different genetic material of Eucalyptus sp. in wood energy production. Therefore, we evaluated three Eucalyptus sp. clones from Gerdau S/A, at four different ages: 3, 4, 5 and 7 years. Five discs were removed from each tree (0%, 25%, 50%, 75%, 100% of the trunk commercial height), and the wood basic density and calorific value were determined. Based on these values we estimated the energy m-3 amount. We observed an effect of age and genetic material for the wood density and the calorific value. Moreover, the amount of energy m-3 increased with increasing age, and the three genetic materials evaluated were significantly different between them. The GG 680 clone showed better performance for this variable, presenting at seven years 2,943 kW.h.m -³ . Note that the selection of the best genetic material must consider the wood technological characteristics, as well as their productivity and effectiveness of technical production.

Crescimento de eucalipto sob efeito de desfolhamento artificial

The objective of this work was to evaluate the effects of total defoliation at planting initial stages, and along the first year of cultivation, on Eucalyptus grandis growth, from planting to plantation cut. Five treatments were tested: without defoliation; one defoliation, at 56 th day after planting (DAP); two defoliations, at 56 th and 143 th DAP; two defoliations, at 56 th and 267 th DAP; and three defoliations, at 56 th , 143 th and 278 th DAP. Trunk diameter at 1.30-m height and the total height of 60 trees were measured from the 21 st to the 92 th cultivation months. The average growth of each treatment was described by nonlinear models and compared by identity tests in order to estimate the tendencies between control and the other treatments in each variable. Defoliation significantly reduces diameter of the trunk and height growth rates, and expressively decreases the income at the plantation cut. However, greater losses were verified after consecutive defoliation, along the first cultivation year. Maintaining areas that suffered severe defoliations at initial planting stages can become economically unfeasible.

Análise econômica de um sistema agrossilvipastoril de área montanhosa na Zona da Mata mineira

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.

Germinação de sementes de Melanoxylon brauna schott em diferentes temperaturas

The objective of this study was to investigate the effect of temperature on the germination of Melanoxylonbrauna seeds and identify cardinal temperatures for germination, as well as to evaluate the efficiency of the electrical conductivity test to determine the cardinal temperatures. Therefore, three testswere performed. In the first test, the determination of imbibition curves was performed at each temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45oC), the seeds were weighed every two hours for a period of 12 hours and after every 12 hours until the root protrusion of 50% of the seeds, or 120 hours when there was no germination. In the second test, to identify the cardinal temperatures, seeds were kept under each temperature for a period of 10 days in DBO under constant light. In the third test, an electrical conductivity test was performed with the seeds incubated for 24, 48 and 72 hours of imbibition in each of the temperatures, and then were placed inerlenmeyer flasks with 75 mL of deionized water at 25oC for 24 hours for subsequent reading of the electrical conductivity. It is more judicious to recommend temperature ranges for germination than punctual temperatures. The cardinal temperatures (theoretical) for the characteristic germination rates are: 12.3oC - minimum - 30.0oC optimal (theoretical) and 42.7oC maximun. The temperature ranges considering all the variables investigated were: 12.1 to 12.6oC (minimum); 30.0-35.8oC (optimum) and 42.4-43.0oC (maximum). The specie has a wide range of germination with respect to temperature, and germination was observed in the temperature range from 12.0 to 42.0oC. The electrical conductivity test was efficient to evaluate the effect of temperature onseeds and according to this test the optimal temperature is 27.0oC.

Parâmetros cinéticos de adesivos produzidos a partir de taninos de Anadenanthera peregrina e Eucalyptus grandis

Due to the petroleum crisis in the Seventies, research had the objective of replace part or the entire conventional adhesive, based on petroleum. One way of replacement was the use of natural sources, as the tannins from some species of tree. However, the tannins present some use limitations, which can be overcome by sulfitation and acid hydrolysis. Therefore, the purpose of this study was evaluate the effect of tannina cid hydrolysis and sulfitation, extracted from the bark of Eucalyptus grandis and Anadenanthera peregrina in the kinetic parameters of tannin adhesives using the technique of differential scanning calorimetry (DSC). The tannins were hydrolyzed with acetic acid or hydrochloric acid 10N, using three pH values and three reaction times. The sulfitation was performed in a 5% sodium sulfite solution, in three reaction times. The activation energy, enthalpy and cure temperature of the adhesive were reduced by hydrolysis and sulfitation of tannins, but showed broadband polymerization. The tannins reaction time had no effect on the kinetic parameters.

Análise fitossociológica e do estoque de carbono no estrato arbóreo de um fragmento de Floresta Estacional Semidecidual

Os estudos direcionados para quantificacao de estoques de carbono fixado por florestas naturais estao em ampla evidencia, assim como a discussao sobre a efetividade da recuperacao de areas degradadas como estrategia para reduzir os niveis de CO2 atmosferico. Neste sentido, tiveram-se dois objetivos neste artigo: i) quantificar o estoque de carbono presente na biomassa da parte aerea de um fragmento de Floresta Estacional Semidecidual Montana, pertencente ao Bioma Mata Atlântica no estado de Minas Gerais e ii) incorporar a variavel estoque de carbono na estrutura horizontal da analise fitossociologica e comparar os resultados aos obtidos pela metodologia padrao, sem utilizar essa variavel no calculo do valor de importâncias das especies. Os resultados indicam que o estoque de carbono encontrado equivale a fragmentos em estagio medio de sucessao, e que a utilizacao da variavel carbono influencia sobremaneira o valor de importância das especies. Esta metodologia serve como suporte para a escolha de especies arboreas de maior potencial para sequestrar carbono e pode subsidiar programas de restauracao de remanescentes florestais do Bioma de Mata Atlântica.

UTILIZAÇÃO DE RESÍDUOS DE COCO ( Cocos nucifera ) CARBONIZADO PARA A PRODUÇÃO DE BRIQUETES

The present work has the objective to produce briquettes by using fine charcoal from coconut wastes as raw material and evaluate the briquette quality. Coconut piths were collected at the city of Touros, in Rio Grande do Norte state. After a 2- month air drying, coconut pith was carbonized and hereafter ground in a hammer mill. The resulting charcoal powder was sieved and the fraction less than 40 mesh was used to produce briquettes according to an entirely randomized designed experiment involving 12 treatments and 3 replications. Starch and clay were employed as binders. The treatments were divided into 3 groups, each group corresponding to a proportion of clay, respectively 12, 15 and 18%, based on the total dry weight of the briquette. Within each group, the proportions of starch were 6, 8, 10 and 12%. The carbon powder was mixed with finely ground clay was added and then the pre-gelatinized starch in water at 80°C. The mass for each treatment was mixed until homogeneous, separating quantities of 17grams of mass for each repetition. The briquettes were produced in a laboratory press (pressure of1500psi and pressing time of 4 minutes).The briquettes were dried in an oven at 60°C until constant weight. After drying, the properties of briquettes were evaluated: bulk density, high calorific value, immediate chemical composition (moisture content, fixed carbon, volatile matter and ash) and compressive strength. Best treatments for trading products were 12/12 e 12/15.

Charcoal briquettes produced with recycled coconut pith

The present work has the objective to produce briquettes by using fine charcoal from coconut wastes as raw material and evaluate the briquette quality. Coconut piths were collected at the city of Touros, in Rio Grande do Norte state. After a 2month air drying, coconut pith was carbonized and hereafter ground in a hammer mill. The resulting charcoal powder was sieved and the fraction less than 40 mesh was used to produce briquettes according to an entirely randomized designed experiment involving 12 treatments and 3 replications. Starch and clay were employed as binders. The treatments were divided into 3 groups, each group corresponding to a proportion of clay, respectively 12, 15 and 18%, based on the total dry weight of the briquette. Within each group, the proportions of starch were 6, 8, 10 and 12%. The carbon powder was mixed with finely ground clay was added and then the pre-gelatinized starch in water at 80°C. The mass for each treatment was mixed until homogeneous, separating quantities of 17grams of mass for each repetition. The briquettes were produced in a laboratory press (pressure of1500psi and pressing time of 4 minutes). The briquettes were dried in an oven at 60°C until constant weight. After drying, the properties of briquettes 1 Engenheiro Florestal, Dr., Professor da Unidade de Ciências Agrárias, Escola Agrícola De Jundiaí,Universidade Federal do Rio Grande do Norte, RN 160 Km 3, s/n, CEP 59280-000, Macaíba (RN), Brasil. aspimenta@ufrnet.br /meire_caico@yahoo.com.br 2 Engenheira Florestal, Dra., Professora do Departamento de Engenharia Florestal, Universidade Federal de Viçosa, Av. P. H.Rolfs, s/n, Campus Universitário, CEP 36571-000, Viçosa (MG), Brasil. cassiacarneiro1@gmail.com 3 Engenheiro Florestal, Dr., Professor da Engenharia Florestal, Universidade Nacional de Brasília, Asa Norte, Caixa Postal 04357, Campus Universitário, CEP 70910-900, Brasília (DF), Brasil. renatovocastro@unb.br Recebido para publicação em 8/11/2012 e aceito em 27/06/2013

Cobertura retrátil no crescimento de mudas clonais de eucalipto

O sucesso na implantacao de povoamentos florestais depende, em grande parte, do desempenho das mudas em resposta as variacoes no ambiente do viveiro. Objetivou-se, neste trabalho, avaliar o crescimento e a qualidade de mudas clonais de eucalipto em resposta a utilizacao de cobertura retratil nos canteiros de crescimento. O experimento foi conduzido no periodo de abril a julho de 2008, constituindo-se de um delineamento inteiramente casualizado em esquema fatorial 2 x 6, em dois ambientes (com cobertura retratil e sem cobertura retratil) e seis diferentes materiais geneticos. Foram avaliadas as caracteristicas altura da parte aerea, diâmetro do colo e pesos de materia seca de raizes, parte aerea e total das mudas. Os resultados indicaram que a utilizacao de cobertura retratil influenciou positivamente no crescimento de mudas clonais de eucalipto, as quais exibiram maiores medias de altura e incremento em biomassa de raizes e total para a maioria dos clones testados, o que contribuiu para o desenvolvimento das plantas, que apresentaram qualidade satisfatoria aos 55 dias.