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The fight for the conservation of the Amazon region is anything but recent. Despite being one of the highest biodiversity assets in the world, it has undergone intense transformations of the landscape since the beginning of the anthropic “invasion” occupation. Changes in land use and occupation are observed for the municipality of Dom Eliseu, located in the zone characterized as the Arc of Deforestation. Given this premise, we designed this study to provide a quantitative understanding of forest fragmentation in the municipality of Dom Eliseu – PA. For this, cloud-free images from the TM (Landsat 5) and OLI (Landsat 8) sensors for 2008 and 2018 were used, respectively, for supervised classification of land use and land cover to identify the forest areas in the study area. The areas of each fragment were quantified and grouped into size classes, considering as very small ( 100 ha) fragments. The indexes used were area, edge, density and size, shape, and central. In total, 33,171 forest fragments were found in 2008, reduced to 32,385 in 2018, representing 42.71% of the forest cover area under study. Quantitative characterizations were made with groups of area indexes density and size, shape, and central area, the latter obtained for the distance of 100 m under edge effect. The area mapping infers that the forest fragments in the area are mainly found by very small fragments, smaller than 5 ha, indicating a high degree of forest fragmentation in this landscape during the two years under study.

Conservation of degraded forests is a challenging issue in the tropics, since the maintenance of environmental services and economic demands must be conciliated. Environmental services must be conserved while degraded tropical forests are demanded to be competitive against more financially profitable land uses as crop fields and pastures. The objective of this study was to evaluate productivity and financial profitability of enrichment planting in degraded forests. Seeds of Schizolobium parahyba var. amazonicum were planted in logging gaps of a 108-ha degraded forest in southeast Para (Brazil) in February 1995 (average = 91.7 seeds ha−1 and 15.3 seeds gap−1). After 13 years (2008), S. parahyba presented a volume increase of 3.1 m3 ha−1 yr−1 for individuals ⩾25 cm in DBH. More than 30% of the planted seeds were able to germinate, establish, and grow up to sizes ⩾25 cm in DBH. A cost-benefit analysis through Net Present Value (NPV) and a sensitivity analysis with different interest rates were performed to compare financial profitability of the treated and control area under roundwood and laminated plus sawnwood production. Enrichment planting using S. parahyba seeds presented higher NPVs in the treated than in control area for all simulations, except roundwood under interest rate of 9% per year.

Commercial height of the tree is a key variable for estimating the wood stock in tropical forests managed for timber production purposes. Most available measurement devices suffer limitations in this type of forest, promoting low precision measurements with high variation errors. The laser meter device appears as a viable alternative, as in addition to using trigonometric principles, it is not necessary that the device is close to the eyes of the meter to carry out the measurement. The device can be used to measure commercial height of trees on flat or sloping terrain, at different distances from the tree. However, there are no studies evaluating the precision of this device. The objective of this study was to determine the precision of the laser meter method for estimating the commercial height of trees, as compared to the actual measurement in a tropical forest in the Brazilian Amazon. Measurements were made on 300 trees with commercial height between 7 and 14 m. Actual commercial heights were measured with graduated ruler. Applied tests were paired t test, graphical analysis of residuals and calculations of bias statistics, mean absolute deviation, standard deviation of differences, and coefficient of determination (R 2). Paired t test indicated that the mean of the heights measured by the laser meter is statistically equal to that of the graduated ruler. Measurements with laser meter did not show bias and had mean error of 0.0745. The standard deviation of the differences indicated dispersion of errors of 0.97, equal to that shown in the graduated rule. Laser meter presents an alternative method for estimating the commercial height of trees in tropical forest in the Brazilian Amazon. There was no tendency to underestimate or overestimate the commercial heights of trees. Use of the laser meter is potentially of use for measuring the commercial height of trees in tropical forests., A new method and device to measure commercial height of trees in natural forests is proposed. The method has, besides practicality, good precision, and low cost, a great differential: The technician does not need to use the device close to the eyes. The technician observes the laser beam in the tree trunk and remains in the same position to realize the three measures necessary to obtain the commercial height. The device can be used to measure commercial height of trees on flat or sloping terrain from any distance from the tree.

O estado do Pará possui uma área extensa de florestas, ricas em espécies que apresentam valor comercial madeireiro e impulsionam de forma direta a economia da Amazônia. Na Microrregião de Paragominas-PA, a produção de compensados constitui uma importante alternativa econômica para o comércio local. Este trabalho teve como objetivo caracterizar a produção da madeira de Paricá proveniente de reflorestamento, como matéria-prima utilizada na produção de compensado, por empresas beneficiadoras sediadas na Microrregião de Paragominas-PA. Foi conduzido um estudo de caso de caráter exploratório e descritivo, para quantificação da produção, identificação da matéria prima utilizada, e análises da estrutura de mercado, do parque tecnológico e da mão de obra empregada. Os dados foram coletados por meio de entrevistas, observação pessoal, conversas informais, participação em reuniões e análise de documentos. Nos resultados, observou-se que as propriedades pesquisadas eram classificadas como de médio e grande porte. Numa mesma área, as espécies de paricá dividiam espaço com eucalipto e soja. As disposições mais utilizadas nas plantações foram: quadrada (3,5m x 3,5m e 3,2m x 3,2m) e retangular (3,0m x 3,5m), contendo respectivamente 816, 976 e 952 árvores por hectare. Contudo, fatores como economia, políticas públicas, insuficiência de embasamentos científicos e tecnologia influenciam na consolidação e no potencial de abastecimento do mercado de compensado regional.PALAVRAS-CHAVE: Florestas Plantadas, Madeira Nativa, Schizolobium parahyba var. amazonicum (Huber x Ducke) Barneby.