RESUMOObjetivou-se, neste estudo, caracterizar a extração e analisar a viabilidade financeira do extrativismo da castanha-do-pará em três municípios da mesorregião Baixo Amazonas, Estado do Pará. Foram realizadas entrevistas com 40 extrativistas e nove atravessadores, selecionados em amostragem não probabilística e intencional. A viabilidade econômica foi estimada por meio de custo de extração, receita líquida (RL), remuneração da mão de obra familiar (RMOF) e renda do trabalho familiar (RTF). A RTF foi de R$ 2.419,56 (Almeirim), R$ 983,22 (Óbidos) e R$ 831,03 (Oriximiná). A RMOF da extração foi de R$ 24,69, R$ 23,98 e R$ 26,47, respectivamente, próxima ao custo de oportunidade evidenciado na região de estudo. A extração da castanhado-pará apresentou-se financeiramente viável para os extrativistas, com a remuneração da mão de obra familiar igual ou superior ao custo de oportunidade da região, sendo mais uma fonte de renda para os comunitários da Amazônia, além de promover a conservação da floresta. Palavras-chave:Bertholletia excelsa, mão de obra familiar, produto florestal não madeireiro. Potential of Brazil nut Extraction to Generate Income in the Communities of the Lower Amazon Mesoregion, Brazil ABSTRACTThe objective of this study was to characterize the extraction and analyze the financial viability of Brazil nut extraction in three municipalities in the Lower Amazon Mesoregion, state of Para, Brazil. Interviews were conducted with 40 workers and 9 dealers selected by intentional nonprobabilistic sampling. Economic viability was estimated by extraction cost, net revenue (NR), family labor remuneration (FLR), and family labor income (FLI). The following amounts of FLI were recorded: R$ 2,419.56 (Almeirim), R$ 983.22 (Obidos) and R$ 831.03 (Oriximiná). The FLR amounts for extraction were R$ 24.69, R$ 23.98, and R$ 26.47, respectively for the municipalities above mentioned, which were close to the opportunity cost for the study region. The extraction of Brazil nuts appears to be financially viable for extraction workers, with family labor remuneration equals or greater than the opportunity cost of the region. Besides promoting the conservation of the forest, this activity is also an extra source of income for the Amazonian community.

O objetivo deste estudo foi determinar, através de métodos de avaliação econômica, a idade econômica de corte de plantações de eucalipto submetidas a desbaste. Para tanto, foram utilizados dados de um experimento de desbastes estabelecido na região nordeste da Bahia. Foram consideradas as variações de intensidades de desbaste (0, 20, 40 e 60% de retirada em área basal) para projeções realizadas em diferentes classes de local. O método de avaliação econômica utilizado foi o valor anual equivalente. Na análise de sensibilidade foram levadas em conta taxas de desconto de 6, 9 e 12%. Os resultados evidenciaram que a rotação econômica propicia maior lucratividade quando se realiza desbaste.

SUMMARYThe aim of this study was to describe the floristic, structure and spatial pattern of species occurring in a natural fragment of the floodplain forest in the lower Tapajós River, Pará. Three hundred and eight contiguous sampling unities of 100 m² were installed, comprising a sampling area of 3.08 ha. In each plot, all individuals with DBH (diameter at breast height of 1.30 cm) equal to or higher than 10 cm were measured, identified, and referenced in Cartesian coordinates (X, Y). The analyses of the diversity and spatial pattern were performed using the Shannon-Weaver index and the Ripley's K function, respectively. There were 1,022 individuals surveyed, including 64 tree species and 33 families. The diversity recorded was 3.03; the total density was determined to be 331.8 individuals ha -1 and basal area of 16.10 m 2 ha -1 . The species of high ecological value were Campsiandra laurifolia, Hevea brasiliensis, Glicoxylon pedicellatum, Tetragastris altissima, Vantanea parviflora and Mabea caudata. The diametric distribution of the community and species, except for Hevea brasiliensis, behaved as expected for uneven-aged forests, and presented an exponential distribution with an inverted J form. The community spatial pattern showed variations depending on the considered distance, however there was a predominance of aggregated distribution. The spatial patterns detected on the species were: I -partially aggregated and random for Vantanea parviflora species, II -completely aggregated to the Hevea brasiliensis and Glicoxylon pedicellatum species, and IIIpredominantly aggregated to Campsiandra laurifolia, Tetragastris altissima and Mabea caudata.

SUMMARYThe aim of this study was to analyze the spatial pattern and sampling methods for Bertholletia excelsa. The inventory of exploration, by mapping Cartesian coordinates of all trees with dbh ≥ 20 cm, was carried out in an area of 1,000.31 ha. For the definition of the diametric structure, multivariate techniques were used: cluster and discriminant analysis. To analyze the spatial patterns, individuals were grouped into three levels: population, young individuals and adults; being the random deviation defined by the Ripley's K function. The forest inventories were simulated with a simple random sampling, systematic and adaptive, taking into account plots of 2,500 m², with a sampling intensity of 15 % and an error range of 10 %. Comparisons between sampling methods were performed for the accuracy and precision. Four hundred and forty six trees were registered, of which 59 were young individuals and 387 were adults. A low number of trees in the early stages and a high number of individuals in the intermediate classes characterize the diametric structure. The spatial pattern of the adult population was aggregated, while the young individuals were randomly distributed. Systematic sampling is the best procedure to estimate the total number of individuals of B. excelsa; however, there is a need to investigate the effect of aggregation and size of the largest plots of 0.25 hectares on the estimates of adaptive cluster sampling.

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Objetivou-se ajustar modelos volumétricos e classificar o potencial volumétrico de madeira de Lecythis lurida (Miers) Mori na Floresta Nacional do Tapajós. Os dados são oriundos de duas Unidades de Produção Anual (UPAs) da área de manejo florestal da Cooperativa Mista da FLONA do Tapajós (COOMFLONA). Foram ajustados modelos volumétricos e escolhido o melhor com base no R²aj., Syx%, significância dos parâmetros e análise gráfica de resíduos. Para a classificação do potencial volumétrico pela estratificação volumétrica, usou-se a distância euclidiana simples como medida de dissimilaridade e o método Ward como algoritmo de agrupamento. A análise discriminante foi aplicada para verificar a veracidade da distinção e da classificação das Unidades de Trabalho (UTs) em classes homogêneas de estoque volumétrico. Os modelos de dupla entrada foram estatisticamente superiores aos de simples entrada, sendo o de Schumacher-Hall o melhor modelo, com R²aj. de 81,62% e Syx% de 16,91%. A análise discriminante indicou que a classificação das UTs nas classes de estoque volumétrico foi 100% correta em que a análise multivariada possibilitou a estratificação da área de exploração em três classes de produtividade para L. lurida, contribuindo para melhor planejamento das atividades florestais que envolvam esta espécie.Palavras-chave: manejo florestal comunitário, estoque produtivo, análise multivariada. FITTING AND CLASSIFICATION OF VOLUMETRIC POTENTIAL FOR Lecythis lurida (MIERS) MORI, TAPAJÓS NATIONAL FOREST ABSTRACT:It was aimed to fit volumetric models and classify the volumetric potential of Lecythis lurida (Miers) Mori in Tapajós National Forest. The data come from two Annual Production Units (UPAs) of the forest management area of Mixed Cooperative of FLONA Tapajós (COOMFLONA). Volumetric models were fitted and the best one was chosen based on R²aj., Syx%, significance of the parameters and graphical analysis of residues. For the classification volumetric potential, the simple Euclidean distance was used as a measure of dissimilarity and the Ward method as clustering algorithm. The discriminant analysis was applied  to verify veracity of the distinction and classification of  Work Units (UTs) in homogeneous classes of volumetric stock. The double-entry models were statistically superior to the single-entry, with the Schumacher-Hall model resulting as the best, with R²aj. of 81.62% and Syx% of 16.91%. The discriminant analysis indicated that the classification of UTs in the volumetric stock classes was 100% correct, in which the multivariate analysis allowed the stratification of the exploitation area in three classes of productive capacity for L. lurida, contributing to the better planning the forest activities involving this species.Keywords: Community forest management, productive stock, multivariate analysis.