No abstract

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.

Objetivou-se neste estudo avaliar o comportamento silvicultural de sete espécies florestais introduzidas em arranjo inicial para sistema de integração pecuária-floresta sobre pastagem degradada em Lavras, Minas Gerais. O trabalho foi instalado em delineamento de blocos casualizados em quatro repetições, 48 plantas úteis por parcela, em arranjo de (3(3x2)+7x2) m. Avaliaram-se as espécies florestais Acacia mangium Willd, Calophyllum brasiliense Cambess, Dipteryx alata Vogel, Eucalyptus urophylla x Eucalyptus grandis (1528 e GG100), Khaya senegalensis A. Juss, Tectona grandis L. e dois materiais de Toona ciliata M. Roemer, propagados por meio vegetativo e via semente. As espécies foram selecionadas, principalmente, pelo valor econômico da madeira, taxa de crescimento em áreas degradadas e múltiplos usos. O comportamento silvicultural foi realizado aos 52 meses pela mensuração da sobrevivência, diâmetro à altura do peito, altura total, volume de madeira e área de projeção de copa, sendo analisados por meio do software R. Os resultados obtidos demonstram que as espécies apresentaram diferente comportamento silvicultural, destacando a adaptação e rusticidade dos híbridos de Eucalyptus urophylla x Eucalyptus grandis e Acacia mangium Willd. Contudo, dentre as espécies testadas, o híbrido de Eucalyptus urophylla x Eucalyptus grandis (GG100 e 1528), A. mangium e T. ciliata clonal apresentaram melhor comportamento silvicultural, com o maior potencial de utilização em sistema de integração pecuária-floresta no arranjo (3(3x2)+7x2) m em pastagem degradada, nas condições edafoclimáticas de Lavras.

The objective of this study was to quantify the accumulation of nutrients in the bark of four eucalyptus clones at 12 years-of-age, planted at different population densities, and the values were extrapolated to kg of nutrients per hectare. The experiment used randomized blocks in a 4 × 3 factorial design and three replications, with four Eucalyptus clones (2486, I182, I144, and GG100) planted at three population densities (416, 833, and 1111 trees ha-1). The rigorous cubage of three trees per plot was performed by collecting discs of bark at the following heights: diameter at breast height (1.30 m), 0, 25, 50, 75, and 100% of the commercial height of the stem. The bark discs of each tree were grouped and used to determine N, P, K, Ca, Mg, and S content, in addition to the basic density. The volume and dry mass of bark per tree was estimated and the accumulation of nutrients per tree ha-1 was estimated sequentially, for each population density. Analysis of variance and Tukey’s post-hoc tests verified that Ca showed the greatest accumulation in the bark, followed by N, K, S, Mg, and P. The increase in population density contributed to higher bark production and greater nutrient accumulation per hectare. However, this increase was not evident when comparing densities of 833 and 1111 trees ha-1.

Flowering acceleration in native Brazilian tree species for genetic conservation and breeding. Ann. For. Res. 63(1):39-52.