ASSESSING ALTERNATIVES TO ESTIMATE THE STEM VOLUME OF A SEASONAL SEMI-DECIDUOUS FOREST

The objective of this study was to evaluate the use of linear and hybrid linear models, artificial neural networks (ANN) and support vector machine (SVM) in the estimation of the stem volume in a Seasonal Semi-deciduous Forest. Cubing data of 99 sample-trees of 15 species were used for this purpose. After analysis, we verified that the inclusion of the species as random effect did not contribute to increase the accuracy of the estimates in the structure of a hybrid model. Artificial neural networks and support vector machines, including species as input categorical variables, were the best alternatives to estimate the stem volume of trees of the Seasonal Semi-deciduous Forest. AbstractThe objective of this study was to evaluate the use of linear and hybrid linear models, artificial neural networks (ANN) and support vector machine (SVM) in the estimation of the stem volume in a Seasonal Semi-deciduous Forest. Cubing data of 99 sample-trees of 15 species were used for this purpose. After analysis, we verified that the inclusion of the species as random effect did not contribute to increase the accuracy of the estimates in the structure of a hybrid model. Artificial neural networks and support vector machines, including species as input categorical variables, were the best alternatives to estimate the stem volume of trees of the Seasonal Semi-deciduous Forest.Keywords: Stem volume; artificial neural networks; support vector machines; hybrid linear models; uneven-aged forest. ResumoAvaliando alternativas para estimar o volume do fuste de uma Floresta Estacional Semidecidual. O objetivo desse estudo foi   avaliar o uso de modelos lineares e lineares mistos, redes neurais   artificiais (RNA) e máquina de vetor de suporte (MVS) na estimação dos   volumes dos fustes de árvores em uma Floresta Estacional Semidecidual. Dados de cubagem de 99 árvores-amostra   de 15 espécies foram utilizados para esta finalidade. Após análises, verificou-se que   a inclusão das espécies como efeito aleatório não contribuiu para aumentar a   exatidão das estimativas na estrutura de um modelo misto. As redes neurais artificiais e   as máquinas de vetores de suporte, incluindo as espécies como variáveis   categóricas de entrada, foram as melhores alternativas para estimar o volume   dos fustes das árvores da Floresta Estacional Semidecidual.Palavras-chaves: Volume do   fuste; redes neurais artificiais; máquinas de vetor de suporte; modelos   lineares mistos; floresta inequiânea.

Individual tree growth models for eucalyptus in northern Brazil

The diameter and height growth model is one of three submodels used for simulating individual tree growth. In Brazil, there are few studies on the dimensional growth of individual trees be they native or exotic species, despite their potential. This study aimed to evaluate diameter and height growth models for individual trees for eucalyptus stands and to validate the best fitting model. Tree diameter and height data were obtained from 48 permanent plots of unthinned stands of Eucalyptus grandis × Eucalyptus urophylla hybrid located in northern Brazil. The evaluation of the diameter and height growth models was based on adjusted coefficient of determination, standard error of estimate as a percentage, trend, root mean square error and Akaike Information Criterion. Analysis also included distribution of residual percentage, statistical significance and signs of the coefficients. The Lundqvist-Korf model provided the most accurate estimates for diameter and height growth, in comparison with the other models, providing better statistical values, greater proximity to observed values and better distribution of residual percentages. The use of this type of model is feasible and can result in significant improvements in the accuracy of yield estimates

Curvas de índices de local em povoamentos de eucalipto obtidas por regressão quantílica

The objective of this work was to obtain site index curves in eucalyptus plantations by quantile regression, and to compare them to the obtained ones with the use of fitted regressions by the method of ordinary least squares. Quantile regression can be used to generate site index curves, especially in the presence of outliers. The method generates a bundle of curves better adjusted to the observed data, compared to the one generated with the estimates of ordinary least squares, either by the guide curve method (anamorphic curves) or by polymorphic curves (using different percentiles).O objetivo deste trabalho foi obter curvas de índice de local, em povoamentos de eucalipto, por meio de regressão quantílica, e compará‑las às obtidas com o uso de regressões ajustadas pelo método de mínimos quadrados ordinários. A regressão quantílica pode ser utilizada para a geração de curvas de índice de local, especialmente em presença de dados discrepantes. O método gera um feixe de curvas mais bem ajustadas aos dados observados, em comparação ao feixe gerado com as estimativas de mínimos quadrados ordinários, seja pelo método da curva‑guia (curvas anamórficas), seja pela geração de curvas polimórficas (com o uso de diferentes percentis)

Estruturação topológica de grandes bases de dados de bacias hidrográficas

O presente trabalho teve como objetivo avaliar o método para delimitação da bacia de contribuição à montante de um ponto selecionado sobre o hidrografia e a obtenção das respectivas características morfométricas, a partir de bases de dados estruturadas topologicamente. Para tanto, utilizou-se o aplicativo Hidrodata 2.0, desenvolvido para o ArcINFO workstation, comparando os seus resultados com os do processo convencional. Os resultados comprovaram que o tempo de processamento demandado para delimitação de bacias e extração de suas características morfométricas a partir de uma base de dados estruturada topologicamente se manteve baixo e constante. Concluiu-se que o método apresentado poderá ser aplicado em qualquer bacia hidrográfica, independentemente do seu tamanho, mesmo com o uso de computadores de configuração mais modesta.The present work aims to present and to evaluate a method for topologically structuring large databases, implemented as a set of AML routines for ArcINFO workstation named Hidrodata. The results proved that the processing time for delineating drainage areas and extracting their morphometric characteristics was kept low and constant. The use of a topologically structured database resulted in a lower demand of processing capacity. It was concluded that the presented approach can be applied for any watershed, independently of its size, even with the use of less-sophisticated computers

Comparison of different approaches to diameter distribution modeling

O objetivo deste estudo foi avaliar a eficiência da função de distribuição de probabilidade Weibull truncada à direita em relação ao procedimento de passo invariante baseado na relação de percentis da distribuição diamétrica. Verificou-se que o modelo de passo invariante apresenta ajustes e predições mais precisas quando comparado com o procedimento tradicional, sendo mais eficiente.Palavras-chave:Passo invariante; função Weibull; avaliação de modelo. AbstractComparison of different approaches to diameter distribution modeling. This study evaluated the efficiency of the Weibull probability distribution function truncated to the right in comparison with the step-invariant procedure to characterize the percentiles of the diameter distribution. The results indicated that the step-invariant procedure provides more accurate adjustments and predictions and is more efficient than the traditional procedure.Keywords: Step invariant; Weibull function; model evaluation.This study evaluated the efficiency of the Weibull probability distribution function truncated to the right in comparison with the step-invariant procedure to characterize the percentiles of the diameter distribution. The results indicated that the step-invariant procedure provides more accurate adjustments and predictions and is more efficient than the traditional procedure

USE OF QUANTILE REGRESSION AND RANSAC ALGORITHM IN FITTING VOLUME EQUATIONS UNDER THE INFLUENCE OF DISCREPANT DATA

The objective of this study was to evaluate three estimation methods to fit volume equations in the presence of influential or leverage data. To do so, data from the forest inventory carried out by the Centro Tecnológico de Minas Gerais Foundation were used to fit the Schumacher and Hall (1933) model in its nonlinear form for Cerradão forest, considering the quantile regression (QR), the RANSAC algorithm and the nonlinear Ordinary Least Squares (OLS) method. The correlation coefficient ( ) between the observed and estimated volumes, root-mean-square error (RMSE), as well as graphical analysis of the dispersion and distribution of the residuals were used as criteria to evaluate the performance of the methods. After the analysis, the nonlinear least squares method presented a slightly better result in terms of the goodness-of-fit statistics, however it altered the expected trend of the fitted curve due to the presence of influential data, which did not happen with the QR and the RANSAC algorithm, as these were more robust in the presence of discrepant data

OPTIMIZATION AND ECONOMIC ANALYSIS OF MULTIPRODUCTS OBTAINED FROM WOOD OF EUCALYPTUS STANDS UNDER DIFFERENT PRODUCTIVE CAPACITY CLASSES AND ROTATION AGES

The present study aimed to analyze the yield and economic viability of the destination, for lumber and energy, of the wood from non-thinned stands of the hybrid Eucalyptus urophylla x Eucalyptus grandis under different productive capacity class and whose production was projected by individual tree growth model to different ages. The simulation of the growth of individual trees was performed by applying the height and diameter growth, and mortality sub-models for three productive capacity classes: high, medium and low. The Kozak model was adjusted to study the stem taper and, in addition, used to optimize patterns for sawing logs and to produce lumber. The economic viability of the projects was evaluated by Net Present Value, Equivalent Periodic Benefit and risk analysis using the Monte Carlo method. It was observed that in areas with less productive capacity the volume of wood destined for energy was greater than 80% and, in areas with greater productive capacity the volume of lumber was greater than 26%. Economic indicators showed that the lumber production was viable at any of the studied rotation age. The risk analysis using the Monte Carlo method did not indicate the possibility of the project being unfeasible under the conditions analyzed. The quantity of different types of products obtained and the wood yield depends on the productive capacity class and age of the stand. The destination of the wood for multiproducts is the most viable option, regardless of the productive capacity class

Growth and yield of commercial plantations of eucalyptus estimated by two categories of models

O objetivo deste trabalho foi avaliar e comparar duas categorias de modelos de crescimento e produção em plantios comerciais de eucalipto. Para isso, foram ajustados um modelo de crescimento e produção para povoamento e outro para árvore individual, por meio de equações simultâneas e redes neurais artificiais, respectivamente. O volume de madeira por área foi estimado em diferentes idades e classes de produtividade. Foram avaliados dados de 63 parcelas permanentes de plantios clonais, não desbastados, do híbrido Eucalyptus grandis x E. urophylla, com os dados de 33 parcelas utilizados para o ajuste do modelo e o treinamento das redes neurais, e os das 30 parcelas restantes, para a validação dos modelos. As duas categorias de modelos ajustaram-se bem aos dados observados. No entanto, na validação dos modelos com dados independentes, o volume de madeira por área foi mais bem estimado com o modelo para árvore individual.The objective of this work was to evaluate and compare two categories of growth and yield models of commercial plantations of eucalyptus. For that, a whole stand model, and an individual tree growth model were adjusted through simultaneous equations and artificial neural networks, respectively. Wood volume per area was estimated for tree different ages and productivity classes. Data of 63 permanent plots of unthinned clonal hybrid Eucalyptus grandis x E. urophylla were evaluated, from which those referring to 33 plots were used for model fitting and neural network training, and those referring to the other 30 plots were used for model validation. The two categories of models adjusted well to the observed data. However, for the validation of the models with independent data, the wood volume per area was better estimated with the individual tree growth model

Influência de estimativas de produção de madeira em processos de regulação florestal utilizando programação linear.

The main objective of this work was to evaluate the consequences of the use of yield and growth estimates from different prediction yield and growth models in a Linear Programming model applied to forest regulation. Thus, using data of continuous forest inventory, the yield estimation in future volume was obtained using a yield model based on age, another one based on age and site index, and a third model that used age and site index besides density, which was represented by the basal area per hectare. Also a model based on data of continuous forest inventory which uses data of volume on a period of time to make linear projections of yield for the next period was tested. Next, a simplified forest regulation problem was proposed and solved by the model I by means of Linear Programming, using data from the four volume prediction models. At the end, the conclusion was: a) that models of forest regulation, supplied with estimates from different yield models, when solved by Linear Programming, result in different ways of treating the forests; b) that the matrix of technological coefficients, supplied with different yield data and for a same objective function affects in a significant way the decision making process.Este trabalho teve como principal objetivo avaliar as conseqüências do uso de estimativas de produção oriundas de diferentes modelos de crescimento e produção em um modelo de Programação Linear aplicado à regulação florestal. Assim, utilizando dados de um inventário florestal contínuo, obtiveram-se diferentes estimativas da produção futura em volume, pelo ajuste de um modelo de produção em função da idade, outro em função da idade e do índice de local e por um terceiro modelo que incluiu, além da idade e do índice de local, a densidade, representada pela área basal por hectare. Testou-se também um modelo baseado nos dados de inventário florestal contínuo que utiliza os dados de volume de um período para fazer projeções lineares da produção para o período seguinte. Em seguida, um problema de regulação florestal simplificado foi idealizado e resolvido pelo modelo I por meio de Programação Linear, utilizando dados oriundos dos quatro modelos de predição do volume. Ao final, concluiu-se: a) que modelos de regulação florestal, alimentados por estimativas provenientes de diferentes modelos de produção, quando resolvidos por Programação Linear, resultam em diferentes maneiras de se conduzir a floresta; b) que a matriz de coeficientes tecnológicos, alimentada por diferentes dados de produção e para uma mesma função objetivo, afeta, de maneira significativa, o processo de tomada de decisão

Floristic changes in a tropical semideciduous forest in Viçosa, MG, between 1994 and 2008

 Este estudo teve como objetivo avaliar mudanças na composição florística de uma Floresta Estacional Semidecidual, através do monitoramento de 10 parcelas permanentes instaladas na Mata da Silvicultura, Viçosa, Minas Gerais. Foram identificados e medidos todos os indivíduos com DAP ≥5 cm, nos anos de 1994, 1997, 2000, 2004 e 2008. Os resultados encontrados mostraram que a área em estudo encontra-se em estágio médio de sucessão, apresentando dominância de espécies secundárias iniciais e tardias. Verificou-se, também, que em função do avanço sucessional da floresta, ocorreram mudanças na composição florística da área ao longo do período monitorado.Palavras-chave: Dinâmica florestal; diversidade; sucessão florestal. AbstractFloristic changes in a tropical semideciduous forest in Viçosa, MG, between 1994 and 2008. This research aimed to evaluate changes in floristic composition of a tropical semideciduous forest, by monitoring 10 permanent plots established in the “Mata da Silvicultura”, Viçosa, Minas Gerais. All individuals with DBH ≥ 5 cm were identified and measured in the years 1994, 1997, 2000, 2004 and 2008. The results revealed that the focused area lies in the intermediate stage of succession, presenting dominance of early and late secondary species. It was also verified that, depending on the progress of the forest succession, changes have occurred in the composition of flora in the area by the monitored period.Keywords: Forest dynamic; diversity; forest succession.AbstractThis research aimed to evaluate changes in floristic composition of a tropical semideciduous forest, by monitoring 10 permanent plots established in the “Mata da Silvicultura”, Viçosa, Minas Gerais. All individuals with DBH ≥ 5 cm were identified and measured in the years 1994, 1997, 2000, 2004 and 2008. The results revealed that the focused area lies in the intermediate stage of succession, presenting dominance of early and late secondary species. It was also verified that, depending on the progress of the forest succession, changes have occurred in the composition of flora in the area by the monitored period.Keywords: Forest dynamic; diversity; forest succession