Antônio Donizette de Oliveira

Continuidade espacial para características dendrométricas (numero de fustes e volume) em plantios de eucalyptus grandis

O objetivo deste estudo foi verificar a continuidade espacial do numero de fustes e do volume nas diferentes formas e intensidades amostrais de Eucalyptus grandis com idade entre 3 e 4 anos. A area de estudo abrangeu quatro talhoes, totalizando 104,71 ha, pertencentes a Ripasa S/A Celulose e Papel. Os dados para a realizacao do estudo de variabilidade espacial foram coletados em parcelas circulares e em parcelas em linhas distribuidas sistematicamente na area, nas intensidades de 1:4 (1 parcela a cada 4 ha), 1:7 e 1:10. Foi possivel verificar que, tanto em numero de fustes quanto em volume, os dados apresentaram distribuicao aproximadamente normal. Pela analise variografica, foi verificado que as caracteristicas numero de fustes e volume de madeira apresentaram-se estruturadas espacialmente. O modelo exponencial foi o que se ajustou melhor aos semivariogramas experimentais das caracteristicas nas diferentes formas de parcela e intensidade amostral. A continuidade espacial foi detectada em todas as intensidades amostrais e formas de parcelas avaliadas, quanto a numero de fustes. Portanto, o uso da estatistica espacial no processamento dessa variavel aumentara a precisao das estimativas. No caso de volume, na intensidade amostral 1:10 nao foi possivel detectar continuidade espacial. Em tal condicao, deve-se utilizar a estatistica classica para processamento do inventario florestal.

Análise multivariada da vegetação como ferramenta para avaliar a reabilitação de dunas litorâneas mineradas em Mataraca, Paraíba, Brasil

The mining of coastal sand dunes in Mataraca, Paraiba, Brazil, to extract titanium-derived minerals requires the removal of the original vegetation and produces huge tailing dunes formed essentially of sterile quartzic sand. These dunes are blown by strong winds throughout the year and may be moved away from the coastline causing serious environmental impacts. Since 1987, the mining company Millennium Inorganic Chemicals from Brazil carries out an Environmental Rehabilitation Program aimed to fix these dunes and reclaim the ecosystem. The objective of this study was to assess the influence of the following factors on vegetation recovery: irrigation, rehabilitation age, soil coating with sugar cane bagasse, and soil coating with forest topsoil (obtained from pre-mining removal). The vegetation was surveyed using the point sampling method with 1,094 sample points distributed systematically in 13 strata defined by different combinations of factors. A total of 3153 individual plants belonging to 24 families and 84 species were recorded and their cover values in each stratum were used in a canonical correspondence analysis. Rehabilitation age was the factor most strongly correlated with the species abundance distribution, followed by addition of forest topsoil, while irrigation and sugar bagasse had no significant influence on vegetation progress.

Volume equations for the savannah (cerrado), in Minas Gerais state

In this work, the physiognomy Savannah (Cerrado), present in three regions of the Sao Francisco River Basin, in Minas Gerais State, was studied with the following objectives: to adjust and to select equations to estimate total volume and stem volume; to test the similarity among volumetric models; to show the behavior of the volume in the stem and branches of the tree, and to evaluate the bark percentage in each diametric class. For this, the rigorous scaling using the method of Huber was accomplished, in which the data base was composed by 497 trees, distributed in six diameter classes, inside the three study areas. The bark thickness at the heights of 0%, 25%, 50%, 75% and 100% of the commercial height was measured. The accuracy of the models was evaluated by the determination coefficient, standard error of estimate and graphic analysis of the residuals. To test model identity, the method used was the one developed by Graybill (1976). The models selected for all the tested variables were the ones of Schumacher and Hall and of Spurr, transformed in logarithm. According to the identity test of models, for all the tested variables, similarity exists among the areas 2 and 3. Regarding to the behavior of volume, it was observed that the smallest diametric classes possess larger stem volume than the branches and that there is also a tendency of decreasing the bark percentage with the increase of the diametric class for the three studied areas.In this work, the physiognomy Savannah (Cerrado), present in three regions of the Sao Francisco River Basin, in Minas Gerais State, was studied with the following objectives: to adjust and to select equations to estimate total volume and stem volume; to test the similarity among volumetric models; to show the behavior of the volume in the stem and branches of the tree, and to evaluate the bark percentage in each diametric class. For this, the rigorous scaling using the method of Huber was accomplished, in which the data base was composed by 497 trees, distributed in six diameter classes, inside the three study areas. The bark thickness at the heights of 0%, 25%, 50%, 75% and 100% of the commercial height was measured. The accuracy of the models was evaluated by the determination coefficient, standard error of estimate and graphic analysis of the residuals. To test model identity, the method used was the one developed by Graybill (1976). The models selected for all the tested variables were the ones of Schumacher and Hall and of Spurr, transformed in logarithm. According to the identity test of models, for all the tested variables, similarity exists among the areas 2 and 3. Regarding to the behavior of volume, it was observed that the smallest diametric classes possess larger stem volume than the branches and that there is also a tendency of decreasing the bark percentage with the increase of the diametric class for the three studied areas.

Modelo para prognose do crescimento e da produção e análise econômica de regimes de manejo para Pinus taeda L.

This study aimed to develop a prognosis system for growth and yield of Pinus taeda L. to simulate and evaluate several management regimes for the production of multiple use clearwood to analyze the economic feasibility for several sites, spacings, and wood discount rates and prices, based on owned and rented land plantations. The developed model was based on the compatibility of stand basal area model and diametric class model. The Weibull distribution was chosen to allow the prognosis for several strata and stand ages. A thinning simulator is then applied to obtain the desired remaining stand. A new prognosis is then made and a new thinning simulation applied. This procedure is repeated up to Pinus sp. the final cutting, using the SPPinus (Prognosis Yield System for Pinus sp.). For the economic analysis, two scenarios were compared, using various numbers, periods and thinning intensities, based on different initial planting intensities and various yield levels. A sensitivity analysis of the economic performance was conducted for each management regime, considering three discount rate levels, two wood price levels and the option of owing or renting land. It was concluded that: the model proposed did not present bias in volume and growth estimates; the management regime with a pre-commercial followed by two commercial thinnings should be adopted; renting land for Pinus sp. plantation is economically feasible but owing land is more profitable; the initial spacing should be of 833 trees/ha; and pruning improves wood quality that increases wood price, that will eventually enhance the economic feasibility of management regimes.

Carbon and biomass stocks in a fragment of cerradão in Minas Gerais state, Brazil

This study aimed at quantifying carbon (C) and biomass stocks in shoot portion, leaf litter, roots and soil within a fragment of dense savanna cerradao, 158.5 ha in area, located in Minas Gerais state. Measures were quantified using dendrometric parameters obtained during the forest inventory and collection of leaf litter, root and soil samples. Furrows were dug in the soil each 100 cm long, 50 cm wide and 100 cm deep in order to collect root samples at depths of 0-30 cm, 30-50 cm and 50-100 cm, and soil samples from the layers 0-10 cm, 10-20 cm, 20-40 cm, 40-60 cm and 60-100 cm, as well as any leaf litter from the surrounding surface. Analyses were performed in the Organic Matter Study Laboratory (DCS/UFLA) to determine C contents in the above matrices, using an Elementar analyzer model Vario TOC Cube. Higher C contents and stocks and lower density were noted in topmost soil layers. In cerradao, shoot portion was found to be the matrix contributing the most to biomass production, followed by roots and leaf litter. Carbon stock in the fragment was 139.7 Mg ha-1. Soil was the matrix contributing the most to stocked C (64.8%), followed by the shoot portion (26.3%), roots (5.2%) and leaf litter (3.7%).

Tamanho e forma de parcelas experimentais para Eremanthus erythropappus

O tamanho adequado e a forma das parcelas experimentais para candeia e uma alternativa para garantir interpretacoes corretas e conclusoes bem fundamentadas sobre o cultivo dessa especie. Assim, neste trabalho, objetivou-se definir o tamanho otimo, tamanhos convenientes e forma adequada de parcelas experimentais para Eremanthus erythropappus, para avaliacao das principais caracteristicas dendrometricas em plantios experimentais. Para isso, foi utilizado um ensaio de uniformidade contendo 400 plantas, as quais tiveram a circunferencia, a altura e o volume determinados. Foram simuladas 31 combinacoes de tamanho/forma de parcelas experimentais. Para a determinacao do tamanho otimo, foram utilizados tres metodos de curvatura e um metodo baseado no modelo linear segmentado com plato. A forma adequada foi determinada a partir do criterio de informacao relativa e coeficiente de variacao. O tamanho conveniente foi estimado pelo de metodo Hatheway. Os resultados e as conclusoes obtidas foram as de que o tamanho de parcelas experimentais para candeia, de modo a permitir analise das principais caracteristicas dendrometricas, deve ser de 60 plantas uteis, sendo a conformacao retangular 2×30 (linhas × plantas) a forma mais adequada. O tamanho conveniente e muito flexivel e permite adequacao do tamanho da parcela experimental com as condicoes, caracteristicas e limitacoes do experimento.

Técnicas geoestatísticas e interpoladores espaciais na estratificação de povoamentos de Eucalyptus sp.

The objectives of this study were to verify the possibility of application of the spatial dependence structure for stratus definition in forest stands and to compare, based on the sampling error, Random Sampling Design (ACS) and Stratified Sampling Design (ACE), being the stratification realized by the spatial interpolators Inverse of Square of Distance (IQD) and Kriging. The data was provided from conventional inventories conducted in the years of 2006 and 2007, in clonal eucalypt stands on projects located in Curvelo, Joao Pinheiro and Montes Claros Counties, in Minas Gerais state. The results showed that, of the 50 projects, 64 % presented medium or high spatial dependence degree, evidencing that geo-statistical methods reduce the error without increasing the costs in the inventory. The stratification based on IQD which was used in the projects with low spatial dependence degree (DE) contributed for a mean reduction of 68.4 % in the sampling error. The use of the kriging in the projects with medium or high DE, contributed for a mean reduction of 47.0 % and 65.7 % in the sampling error, respectively. Even in the projects where the spatial dependence structure was detected, the stratification based on IQD generates improvement of the estimates in the ACE compared to the ACS.

Economic feasibility and rotation age for stands of candeia (Eremanthus erythropappus)

Cultivation of nonnative candeia is an alternative way of obtaining raw material to meet the market demands for essential oils and fence posts. A successful stand is conditional on careful planning intended to optimize activities and make the project economically feasible. The objective of this study was to analyze the economic feasibility and to determine the economic rotation age for stands of candeia (Eremanthus erythropappus) using different interrow spacing arrangements, as well as to analyze the sensitivity of both economic indicators for candeia and economic rotation to variations in cash flow variables. Equivalent Annual Value (VAE) was the method used for the economic analyses. A simulation was carried out to detect VAE sensitivity to changes in variables related to cash flow. It was concluded that candeia cultivation can be profitable when spacing arrangements are 1.5 x 2.0 m or more. Arrangements denser than that are economically unfeasible for the ages being analyzed. Among the analyzed spacing arrangements, 1.5 x 3.0 m was found to be the most profitable and less risky. The economic rotation age for candeia is 15 years using 1.5 x 1.5 m spacing; 13 years using 1.5 x 2.0m and 1.5 x 2.5 m spacing; and 12 years using 1.5 x 3.0 m spacing. Proportional variations in timber price, volume output and interest rate implied inversely proportional variations in economic rotation for the spacing arrangements being studied. Conversely, proportional variations in seedling price implied directly proportional variations in rotation. Changes in land price did not affect economic rotation for any of the spacing arrangements.

ECONOMIC VIABILITY AND ROTATION OF FORESTRY PLANTATIONS OF CANDEIA (Eremanthus erythropappus), UNDER CONDITIONS OF RISK

The general objective of this paper was studying the economic feasibility and determining the economic rotation of candeia planting at various spacings under risky conditions. The study was conducted from an experimental planting of candeia consisting of four spacings (1.5 x 1.5 m, 1.5 x 2.0 m, 1.5 x 2.5 m and 1.5 x 3.0 m) for which the cash flows related to the different cutting ages were obtained. For the risk analysis the Monte Carlo method was used, its having the Equivalent Annual Value (EAV) as the output variable (output) and as input variables (sources of uncertainty) the probability distributions concerning the price of the seedlings, land and wood, the harvest cost, interest rates and timber production. The simulation constituted in the doing of 50,000 iterations from where the information necessary to the analyses was extracted. It was concluded that the 1.5 x 3.0 m spacing was the most economically viable and presented a lower risk level than the other spacings. The economic rotation was 12, 13, 13 and 15 years for the spacings 1.5 x 3.0 m, 1.5 x 2.5 m, 1.5 x 2.0m and 1.5 x 1.5m, respectively. Information obtained about the economic risks involved in planting candle serve as a tool to aid in making decisions regarding new plantings of this species and also as a basis for future experiments with the same, seeking to improve its culture.

Dominant height projection model with the addition of environmental variables

This study investigated the behavior of climatic variables inserted as inclination modifiers of the Chapman-Richards model for estimating dominant height. Thus, 1507 data pairs from a Continuous Forestry Inventory of clonal eucalyptus stands were used. The stands are located in the States of Espirito Santo and southern Bahia. The climatic variables were inserted in the dominant height model because the model is a key variable in the whole prognosis system. The models were adjusted using 1360 data pairs, where the rest of the data was reserved for model validation. The climatic variables were selected by using the Backward model construction method. The climatic variables indicated by the Backward method and inserted in the model were: mean monthly precipitation and solar radiation. The inclusion of climatic variables in the model resulted in a precision gain of 19.8% for dominant height projection values when compared with the conventional model. The advantage of the method used in this study is the actualization of inventory data contemplating climatic history and productivity estimates in areas without prior plantation.