Pasture implantation fragments and reduces the Amazonian forest area. The objective was to quantify landscape changes in 1985, 2000 and 2015 in northern Mato Grosso, Brazil. The study was carried out in three scenes obtained by the LANDSAT satellite of a microbasin (2742.33 ha) in the municipality of Alta Floresta. Forest, water bodies, pasture and exposed soil were the thematic classes determined to e mapping the land use evolution. The edge, density and shape indexes of the fragments were measured. Normalized vegetation difference (NDVI) values were high in 1985. Land use and occupation over 15 years (1985–2000) reduced forest cover by 69.8%, but it increased by 1.7% over the next 15 years (2000–2015). The number of exposed soil patches increased between the periods, but the total area and number of the patches of the forest fragments decreased. The high values of NDVI in 1985 showed vegetated areas with high density. Reducing forest cover decreases the size of the fragments, increases the isolation and the number of soil patches exposed. The mapping of land use showed a reduction of the Amazon forest in the microbasin in the north of Mato Grosso, in the years 2000 and 2015 compared to 1985.

Changing hydrological processes and soil characteristics are of major environmental concern in surface mining. Runoff may be the best factor for determining the efficiency of rehabilitation after this type of mining, and needs more in-depth studies, but the environmental factors require more attention in order to control that runoff.The objective of this study was to compare the runoff during post-mining rehabilitation after the extraction of bauxite with that before mining, and to identify the factors that most affect it. Runoff from before the mining operations and during the rehabilitation after those operations were collected in seven plots in the area of a bauxite mine in southeastern Minas Gerais State, Brazil. The physical-environmental and anthropic factors interfering with the runoff were characterized for both periods, and their results were submitted to principal component analysis to define the parameters, which most demand attention in the mining rehabilitation stage. This study provides the first records of runoff in the field in areas rehabilitated after surface mining in Brazil, where the runoff decreased (1.75-times or 42.79%) from 0.76 to 0.30% of the precipitation during rehabilitation, compared to the reference area.The total porosity, density, and resistance of the soil, associated with the maintenance of slope, surface roughness, and vegetation cover, are the factors demanding more attention during the rehabilitation stage of surface mining in order to minimize runoff.

Research highlights: We used Dijkstra Algorithm (DA) to define optimal allocation of yards in order to minimize total skid-trail’s distance in the Amazon Forest. DA minimized trails’ distances and associated transportation costs, leading to an even smaller value when the current planning was disregarded and suggesting the reduction of deleterious environmental externalities. Background and objectives: We sought to answer if it is possible to optimize distances and intrinsic costs in the management of Amazonian forests using DA. The objective was to minimize skid trails distances by best allocating yards using DA and to compare four scenarios of forest harvest planning in the Brazilian Amazon. Materials and methods: Tree census data from Gênesis-Salém Farm, state of Pará, Brazil, were used. The yards and roads located by Grupo Arboris (scenario 1) were compared to three alternative scenarios in terms of total skid distance, trails and road densities, and skidding costs for three successive harvests, seeking to minimize total skid-trails’ distance. Alternative scenarios were to keep the number of yards within work units (WU) and place them in the edge of existing roads (scenario 2); keep the number of yards within each WU (scenario 3); and place 23 yards, disregarding the current planning (scenario 4). Results: Total skid-trail’s distance, number of trees above optimal extraction distance and densities of skid trails and roads were smaller in scenarios 2, 3, and 4, compared to the current yard allocation (scenario 1). Scenario 4, with fewer restrictions, reduced skid-trails’ distances by 23%. Harvest costs decreased from scenario 1 to 4 in all three harvest cycles. Conclusions: DA allowed optimized distribution of yards and skid trails and generated efficient results for harvest planning. This reinforces the importance of optimized planning, which establishes satisfactory results in the effort to reduce costs and environmental impact keeping high efficiency.

RESUMO O gênero Senna Mill. possui distribuição Pantropical e está representado por 300 espécies, dentre elas, 80 no Brasil e 22 em Mato Grosso. O gênero é reconhecido principalmente pela presença de nectários entre os folíolos na maioria das espécies, anteras basifixas e poricidas, ausência de bractéolas e também pelos legumes deiscentes ou raramente indeiscentes. O objetivo foi apresentar uma contribuição taxonômica das espécies Senna bacillaris (L.f.) H.S.Irwin & Barneby e S. cana (Nees & Mart.) H.S. Irwin & Barneby para a flora de Mato Grosso a partir do estudo taxonômico das novas ocorrências depositadas no Herbário da Amazônia Meridional (HERBAM). O trabalho foi realizado entre março e junho de 2016, a partir da análise morfológica das exsicatas de Senna depositadas no HERBAM. O HERBAM possui exsicatas de 15 espécies de Senna, todas coletadas em Mato Grosso, dentre elas, S. bacillaris e S. cana não citadas para o Estado no site Flora do Brasil. S. bacillaris foi coletada no município de Paranaíta. Todas as folhas tem nectários entre os pares de folíolos, estreitamente piriformes, folíolos 2 pares, 5,5-6,5x3-4 cm. S. cana foi coletada no município de Alta Floresta e possui nectários entre todos os pares de folíolos, cônicos, folíolos 4-8 pares, 4,2-6,9x1,8-2,2 cm. Os caracteres de S. bacillaris foram mais consistentes conforme a descrição da última revisão do gênero, enquanto que, S. cana, apresentou maior variação morfológica em relação aos nectários extraflorais. O trabalho reforça a ampliação de 22 para 24 espécies de Senna para a Flora de Mato Grosso.

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