RESUMOO presente estudo objetivou analisar a composição florística atual da regeneração natural, contrastando-a com levantamentos anteriores pertencentes a um monitoramento iniciado em 1992, em fragmento de Floresta Estacional Semidecidual Montana, em Viçosa, MG. Os locais de estudo correspondem a dez sítios escolhidos em função das características fisiográficas declividade, exposição e posição topográfica do terreno. Foram estimados os índices de regeneração natural por espécie para cada classe de tamanho de planta (RNC) para obtenção do índice de regeneração natural total (RNT). Foram amostrados 3.516 indivíduos, pertencentes a 140 morfoespécies arbóreas, incluindo indivíduos de 10 cm a 3 m de altura e diâmetro a 1,3 m (DAP) menor que 5 cm. O maior número de indivíduos foi amostrado nas famílias Rubiaceae, Fabaceae Mimosoideae, Monimiaceae, Fabaceae Papilionoideae, mas as famílias mais ricas foram Fabaceae Caesalpinoideae, Fabaceae Papilionoideae, Euphorbiaceae, Lauraceae, Myrtaceae e Rubiaceae. As espécies que apresentaram os maiores RNTs foram: Psychotria sessilis, Siparuna guianensis, Anadenanthera peregrina e Piptadenia gonoacantha. Este monitoramento sugere uma substituição contínua de espécies de estágios iniciais de sucessão por outras de estágios mais avançados, demonstrando a importância da proteção dos fragmentos florestais remanescentes para a manutenção ou aumento da biodiversidade da região. Palavras-chave: composição florística; banco de plântulas; monitoramento; sucessão vegetal. ABSTRACTThe current study aimed to analyse the tree species natural regeneration floristic composition in a Mountain Seasonal Semideciduous Forest fragment in the domain of the Atlantic Forest, in southeastern Brazil (20°45'S, 42°55'W) in order to subsidize secondary natural forest management. Ten sites were selected based on their aspects, slopes and topographic positions. Natural regeneration indexes were estimated for each tree species per size classes to obtain the Total Natural Regeneration Index (TNR) for each species. It was sampled a total of 3,516 individuals of 140 tree species varying from 10 cm to 5 m height with diameter at the height of 1.3 m (DBH) smaller than 5 cm. The largest numbers of individuals were sampled in the families Rubiaceae, Fabaceae Mimosoideae, Monimiaceae, Fabaceae Papilionoideae, and the richest families were Fabaceae Caesalpinoideae, Fabaceae Papilionoideae, Euphorbiaceae, Lauraceae, Myrtaceae
This study aimed to identify pruning intensity and frequency that can be applied to eucalypt without imposing growth reduction, in an agroforestry system in Brazil (17°36' S and 46°42'
The objectives of the present work were to determine the properties of wood and charcoal from Eucalyptus clones and assess impacts of charcoal features on the CO 2 gasification reactivity and to compare with coke reactivity. Gasification reactivity was performed using charcoal particles in a furnace setup at 820 °C, under CO 2 atmosphere. The results show that there is wood variability among evaluated clones and strong correlations between wood and charcoal properties. All charcoals had higher reactivity in comparison to coke. The decrease in porosity and increase in apparent density in Eucalyptus wood led to a slight decrease of CO2 gasification reactivity. In addition, strong positive correlation between charcoal reactivity and potassium concentration (K) was found.
To increase production and decrease the heterogeneity of charcoal produced in rectangular kilns, the control of carbonization must be carried out based on the kiln internal temperature. The objective of this work was to analyze the maximum carbonization temperature and the time of thermal degradation at temperatures above 290 °C based on the internal kiln wall temperatures, in addition to evaluating charcoal properties in different positions of a rectangular kiln. Wood from the hybrid Eucalyptus urophylla x E. grandis at seven years of age was used for carbonization in rectangular kiln where temperature was monitored and controlled. Process parameters and charcoal quality were evaluated in seven positions in the rectangular kiln. Positions 1 and 7 had higher maximum temperature values and thermal degradation time at temperatures above 290 °C in comparison with the other positions, which presented similar values. There was no significant effect of kiln position on the characteristics of charcoal, which presented average values of 234.61 kg m-3 of bulk density; 55.87% of pieces with size greater than 30 mm; 19.77% of fines (granulometry < 9.5 mm); and 20.80% of friability, 75.39% of fixed carbon, 24.37% of volatile materials, and 0.24% of ash. It was concluded that the kiln position affects the temperature and time of thermal degradation; however, the control of temperature guarantees the production of homogeneous charcoal throughout the kiln, presenting satisfactory quality for steel industry usage.
-A pruned stand of eucalypt clone underwent five thinning treatments with the removal of different proportion of the planted trees, at different ages: a) 0% -unthinned, b) 35% at 55 months, c) 35% at 81 months, d) 70% at 81 months, removing sprouts in the thinned plant stumps and, e) 70% at 81 months, without coppice sprouts removal. By the age of 141 months, the Weibull distribution showed higher number of trees in the smallest diameter classes for the unthinned treatment. The 70% thinning, with thinned coppice sprouts removal, presented higher number of individuals in the largest diameter classes. Height and yield were the smallest with the removal of 70% of the trees at 81 months, maintaining coppice sprouts. The afterthinning periodic annual increment was greater by thinning 35% of the trees at 55 months resulting in greater number of trees in the largest diameter classes as compared to the other treatments. Yield was higher for the unthinned treatment. The results of this study indicated that thinning 70% of the trees at the age of 81 months, with coppice sprout removal, could be recommended to obtain trees of larger diameter for multiproduct.Keywords: Forest yield; Diameter distribution; Eucalypt clone. EFEITO DO DESBASTE SOBRE O CRESCIMENTO DE PLANTAS DE CLONE DE EUCALIPTO DESRAMADO RESUMO -Um povoamento desramado de eucalipto foi submetido a cinco tratamentos de desbaste, com remoção de diferentes proporções das árvores plantadas e idades: a) 0% não desbastado, b) 35% aos 55 meses, c) 35% aos 81 meses, d) 70% aos 81 meses, removendo a brotação nas cepas desbastadas e e)
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