887 resultados para timber sleepers
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The aim of this study was to determine the effect of nitrogen (N) and the phosphorus (P) in seedlings of Amburana cearensis planted in areas occupied by Brachiaria decumbens, in an Oxisol, which originally had a Dense Savanna and in a Plinthic surrounding a Gallery Forest. We evaluated the response of A. cearensisgrowth and survival in the absence and doses of -1 10, 20 and 40 kg ha N, as urea and absence and doses of 10, 20 and -1 40 kg ha P, in the form of triple superphosphate in a randomized complete block design. We evaluated the stem diameter at four, eight and twelve months after planting. At the end of the first year were evaluated crown diameter and survival. According to the classification proposed in this study the growth of A. cearensis can be considered very slow in the Oxisol, regardless of fertilization, very slow when fertilized with N in the Plinthic and slow when fertilized with P. Despite the lower growth in Oxisol, the A. cearensis showed higher nutritional requirement there. The A. cearensis seedlings showed moderate nutritional requirement for N and high for P. In Plinthic, their nutritional requirement for P was moderate and total N present in the soil was sufficient to meet growth demand in this stage. This small nutritional requirement for N may be associated with its ability to nodulation.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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O objetivo deste trabalho foi estimar o valor econômico e a margem de comercialização da madeira em tora oriunda de áreas manejadas. Essa cadeia, além de produzir margem positiva, os valores são relativamente superiores aos gerados nas atividades que concorrem para o desmatamento na Amazônia para se estabelecerem. Adicionalmente, determinou-se o coeficiente médio de desdobramento de 37,3% (2,68 m3 de madeira em tora para cada 1,0 m3 de madeira serrada), o qual revelou baixo grau tecnológico das empresas. O valor econômico médio da extração e comercialização da madeira em pé no mercado local foi de R$ 23,48/m3, tendo um valor mínimo de R$ 9,06/m3 para as espécies da categoria C4 (madeira branca) e um máximo de R$ 55,63/m3 para as espécies da categoria C1 (madeira especial). Assim, para um fluxo de 30 anos e extração de 25 m3/ha nos planos de manejo das áreas de concessão florestal do Estado do Pará, gera-se um valor médio de R$ 587,00/ha, ou R$ 19,56/ha/ano. No fluxo de 30 anos, esse resultado é relativamente superior ao gerado pelas atividades de pecuária extensiva (em torno de R$ 180,00/ha) e das lavouras de grãos (em torno dos R$ 420,00/ha), principais responsáveis pelo desmatamento da Amazônia. Também, apresenta maior rentabilidade do que o reflorestamento com paricá, que gera R$ 192,26/ha. A margem de comercialização indicou que a sociedade tende a se apropriar de 14,3% do valor econômico gerado na cadeia da madeira oriunda dos contratos de concessão florestal.
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Nomadic Plains peoples such as the Cheyenne and Sioux have become the stereotypical image of North American Indians in general. In contrast to the hunting and gathering lifestyle of these groups, however, many Plains tribes lived in settled villages and grew extensive garden crops through much of the past millennium. These groups developed a habitation distinctly characteristic of the Plains village way of life-sturdy, earth-covered timber structures known as earth lodges. The remains of thousands of these structures dot the landscape of the Central and Northern Plains. Lodges of various forms persisted from about 1000 CE into the twentieth century. Particularly characteristic of the Pawnee, Arikara, Mandan, and Hidatsa, earthlodges were also adopted by several other Plains tribes. In this well-illustrated volume eight authors offer nine essays that explore the earth lodge as a subject warranting archaeological and anthropological research in its own right and from numerous perspectives.
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We conducted a comprehensive research project on elk in the Pine Ridge region of northwestern Nebraska from 1995 to 2002 to determine ecological factors that could be used to improve management and reduce damage. The population ranged from 120 to 150 animals, with an average calf:cow ratio of 0.5:1 and bull:cow ratio of 0.4:1. We located 21 radio-collared female elk 6,311 times during 1995 to 1997. Seasonal home ranges of 2 herds were 10 and 44 km2, while average annual home ranges of the herds were much larger (483 and 440 km2, respectively). All wintering areas (n = 21) and 80% of the calving areas (n = 22) were located on privately-owned land. Active timber harvest temporarily displaced elk, most notably during the calving season. Elk shifted home ranges in association with the seasonal availability of agricultural crops, in particular, alfalfa, oats, and winter wheat. Population models indicated that static levels of hunting mortality would lead to a stable population of about 130 elk over 10 years. Most landowners in the Pine Ridge (57%) favored free-ranging elk, but 26% were concerned about damage to agricultural crops and competition with livestock. Habitat suitability models and estimates of social carrying capacity indicate that up to 600 elk could be sustained in the Pine Ridge without significant impacts to landowners. We recommended an integrated management program used to enhance elk habitat on publicly-owned land and redistribute elk from privately-owned land.
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Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of Sao Paulo: Parque Estadual Turistico do Alto do Ribeira and Parque Estadual de Campos de Jordao. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N), basal respiration (BR), the metabolic quotient (qCO(2)) and the following enzyme activities: beta-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA) were evaluated. The sampling period (dry or rainy season) influenced the results of mainly MB-C, MB-N, BR, and qCO(2). The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO(2), suggesting an advanced stage of succession.
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Premise of the study: Microsatellite markers were developed and characterized to investigate genetic diversity and gene flow and to help in conservation efforts for the endangered timber species Plathymenia reticulata. Methods and Results: Eleven microsatellite loci were characterized using 60 adult trees of two populations of P. reticulata from the Atlantic Forest of southern Bahia, Brazil. Of these, nine loci were polymorphic, with an average of 4.39 alleles per locus. The average expected heterozygosity per population ranged from 0.47 to 0.55. The combined exclusion probability was 0.99996. Conclusions: Our results reveal that the microsatellite markers developed in this study are an effective tool for paternity and genetic structure analysis that may be useful for conservation strategies.
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Euterpe edulis is an endangered species due to palm heart overharvesting, the most important non-timber forest product of the Brazilian Atlantic Forest, and fruit exploitation has been introduced as a low impacting alternative. However, E. edulis is a keystone species for frugivores birds, and even the impact of fruit exploitation needs to be better investigated. Since this species occurs over contrasting habitats, the establishment of site-specific standards and limits for exploitation may also be essential to achieve truly sustainable management. In this context, we sought to investigate how soil chemical composition would potentially affect E. edulis (Arecaceae) palm heart and fruit exploitation considering current standards of management. We studied natural populations found in Restinga Forest and Atlantic Rainforest remnants established within Natural Reserves of Sao Paulo State, SE Brazil, where 10.24 ha permanent plots, composed of a grid of 256 subplots (20 m x 20 m), were located. In each of these subplots, we evaluated soil chemical composition and diameter at breast height of E. edulis individuals. Additionally, we evaluated fruit yield in 2008 and 2009 in 20 individuals per year. The Atlantic Rainforest population had a much higher proportion of larger diameter individuals than the population from the Restinga Forest, as a result of habitat-mediated effects, especially those related to soil. Sodium and potassium concentration in Restinga Forest soils, which have strong negative and positive effect on palm growth, respectively, played a key role in determining those differences. Overall, the number of fruits that could be exploited in the Atlantic Rainforest was four times higher than in Restinga Forest. If current rules for palm heart and fruit harvesting were followed without any restriction to different habitats, Restinga Forest populations are under severe threat, as this study shows that they are not suitable for sustainable management of both fruits and palm heart. Hence, a habitat-specific approach of sustainable management is needed for this species in order to respect the demographic and ecological dynamics of each population to be managed. These findings suggest that any effort to create general management standards of low impacting harvesting may be unsuccessful if the species of interest occur over a wide range of ecosystems. (C) 2012 Elsevier B.V. All rights reserved.
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Abstract Background In recent years, the growing demand for biofuels has encouraged the search for different sources of underutilized lignocellulosic feedstocks that are available in sufficient abundance to be used for sustainable biofuel production. Much attention has been focused on biomass from grass. However, large amounts of timber residues such as eucalyptus bark are available and represent a potential source for conversion to bioethanol. In the present paper, we investigate the effects of a delignification process with increasing sodium hydroxide concentrations, preceded or not by diluted acid, on the bark of two eucalyptus clones: Eucalyptus grandis (EG) and the hybrid, E. grandis x urophylla (HGU). The enzymatic digestibility and total cellulose conversion were measured, along with the effect on the composition of the solid and the liquor fractions. Barks were also assessed using Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), X-Ray diffraction, and scanning electron microscopy (SEM). Results Compositional analysis revealed an increase in the cellulose content, reaching around 81% and 76% of glucose for HGU and EG, respectively, using a two-step treatment with HCl 1%, followed by 4% NaOH. Lignin removal was 84% (HGU) and 79% (EG), while the hemicellulose removal was 95% and 97% for HGU and EG, respectively. However, when we applied a one-step treatment, with 4% NaOH, higher hydrolysis efficiencies were found after 48 h for both clones, reaching almost 100% for HGU and 80% for EG, in spite of the lower lignin and hemicellulose removal. Total cellulose conversion increased from 5% and 7% to around 65% for HGU and 59% for EG. NMR and FTIR provided important insight into the lignin and hemicellulose removal and SEM studies shed light on the cell-wall unstructuring after pretreatment and lignin migration and precipitation on the fibers surface, which explain the different hydrolysis rates found for the clones. Conclusion Our results show that the single step alkaline pretreatment improves the enzymatic digestibility of Eucalyptus bark. Furthermore, the chemical and physical methods combined in this study provide a better comprehension of the pretreatment effects on cell-wall and the factors that influence enzymatic digestibility of this forest residue.
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Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of São Paulo: Parque Estadual Turístico do Alto do Ribeira and Parque Estadual de Campos de Jordão. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N), basal respiration (BR), the metabolic quotient (qCO2) and the following enzyme activities: β-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA) were evaluated. The sampling period (dry or rainy season) influenced the results of mainly MB-C, MB-N, BR, and qCO2. The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO2, suggesting an advanced stage of succession.
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Vigas são elementos estruturais encontrados na maioria das construções civis. Dentre os materiais de engenharia, destaca-se a madeira, por ter resistência mecânica satisfatória aliada a baixa densidade. A madeira roliça apresenta-se como boa solução na confecção de vigas, uma vez que não precisa ser processada, como é o caso da madeira serrada. O projeto de elementos estruturais de madeira requer o conhecimento de suas propriedades físicas e mecânicas, obtidas segundo as premissas de documentos normativos. Em se tratando da madeira roliça, os documentos normativos nacionais que tratam da determinação das propriedades de resistência e rigidez estão vigentes há mais de vinte anos sem revisão técnica. De forma geral, tanto as normas nacionais como as internacionais idealizam geometria troncocônica para as peças roliças de madeira, implicando equações simplificadas incapazes de prever a influência das irregularidades da forma na determinação do módulo de elasticidade longitudinal. Este trabalho objetiva avaliar a influência das irregularidades da geometria em peças roliças de madeira Corymbia citriodora e Pinus caribaea no cálculo do módulo de elasticidade longitudinal. Para tanto, utilizou-se do ensaio de flexão estática a três pontos, considerando também um modelo matemático simplificado, assumindo seção circular constante para a forma do elemento. As irregularidades das peças são consideradas nos modelos numéricos, constituídos de elementos finitos de barra e tridimensionais. Os resultados encontrados revelam equivalência estatística entre os módulos de elasticidade para ambas as formas de cálculo, indicando ser plausível a consideração de seção circular constante para as peças de madeira aqui avaliadas.
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[ES] Buscar soluciones contra los daños que provoca la humedad en la madera de construcción es un objetivo común de las ciudades costeras. La tradición, la cultura, la economía y otros factores hacen que en cada una de ellas se utilicen maderas y técnicas distintas, obteniendo unos resultados concretos. Canarias, plataforma tricontinental, es el eje de partida del presente estudio, que expone usos tradicionales y actuales de la madera en las tres ciudades, influencias recíprocas en el pasado y el camino para un aprovechamiento óptimo de la cultura global en el futuro.
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This work presents a program for simulations of vehicle-track and vehicle-trackstructure dynamic interaction . The method used is computationally efficient in the sense that a reduced number of coordinates is sufficient and doesn’t require high efficiency computers. The method proposes a modal substructuring approach of the system by modelling rails , sleepers and underlying structure with modal coordinates, the vehicle with physical lumped elements coordinates and by introducing interconnection elements between these structures (wheel-rail contact, railpads and ballast) by means of their interaction forces. The Frequency response function (FRF) is also calculated for both cases of track over a structure (a bridge, a viaduct ...) and for the simple vehicle-track program; for each case the vehicle effect on the FRF is then analyzed through the comparison of the FRFs obtained introducing or not a simplified vehicle on the system.
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Seit Beginn der Waldzustandserhebungen im Jahr 1984 verschlechterte sich der Zustand der Eiche sowohl auf Bundesebene als auch im Land Rheinland-Pfalz deutlich. 1998 konnten nur noch 5 % der rheinland-pfälzischen Eichen in die Kategorie "ohne Schadensmerkmale" eingestuft werden. Vor diesem Hintergrund ergab sich die Notwendigkeit, die biotischen Stress- und Schadfaktoren näher zu untersuchen. Im Rahmen der vorliegenden Arbeit lag der Fokus auf den holzbewohnenden Käfern von Traubeneichen (Quercus petraea) aus dem Pfälzerwald. Zu diesem Zweck wurden für die erste Probenserie Untersuchungsbäume aus den Vitalitätsstufen 'vital', 'geschädigt', 'ein Jahr tot' und 'zwei Jahre tot' ausgewählt und in die drei Straten Stammfuß, Kronenansatz und Derbholz unterteilt. In der zweiten Probenserie kamen keine 'vitalen' Stämme mehr zum Einsatz. Die einzelnen Proben wurden in Fasseklektoren überführt, in denen die xylobionten Käfer ihre Entwicklung beenden und schlüpfen konnten. Die erste Probenserie wurde im Herbst 1998 entnommen, die zweite Serie im darauffolgenden Herbst. Zusätzlich zu diesen Laboruntersuchungen wurden Freilanduntersuchungen mit Stammeklektoren an vier stehenden Eichen im Wald durchgeführt. Die gefangenen Tiere wurden nach Ordnungen sortiert und gezählt, die Käfer nach Möglichkeit bis zur Art bestimmt. Die Ergebnisse der ersten und zweiten Serie wurden in Abundanzen (Ind./m² Rindenoberfläche) umgerechnet, um einen Vergleich der Proben untereinander möglich zu machen. Insgesamt wurden aus den Fasseklektoren beider Serien Käfer mit einer Abundanz von 36.990 Ind./m² ausgewertet. In den Fallen der Stammeklektoren wurden insgesamt 1.487 Käfer gefunden. Den weitaus größten Teil der Käfer der Fasseklektoren stellen die Borkenkäfer (Scolytidae). Dieses Ergebnis schlägt sich auch in der Betrachtung der Dominanz der einzelnen Arten nieder. In nahezu allen Fällen gehörten die Hauptarten in die Familie Scolytidae. Der mit den Absterbeerscheinungen der Eichen in Verbindung gebrachte Prachtkäfer Agrilus biguttatus (Buprestidae) trat in deutlich geringeren Abundanzen auf. Aufgrund seiner Fraßtätigkeit (Ringelung der Larven im Kambialbereich der Bäume) gehört er aber zu den potentiell stark schädigenden Käfern. Neben A. biguttatus sind auch A. sulcicollis und die gefundenen Borkenkäfer in der Lage, vorgeschädigte und geschwächte Eichen zu befallen und noch weiter zu schwächen. Aus waldhygienischen Gründen sollten deshalb regelmäßige Kontrollen durchgeführt werden. Bei erkennbarem Befall sollten die betroffenen Bäume gefällt und aus dem Bestand entfernt werden. Langfristig können die Vermeidung von nicht-standortgerechtem Eichenanbau und das Anlegen von naturnahen Mischbeständen zu den waldbaulichen Maßnahmen gerechnet werden, die eine Reduktion des Infektionsrisikos zur Folge haben. Die 'ein Jahr toten' Bäume wiesen die mit Abstand höchste Abundanz an Lebendholzbesiedlern auf. Bäume, die bereits ein Jahr länger tot im Bestand standen, wurden von deutlich weniger Lebendholzbesiedlern befallen, d.h. von 'zwei Jahre toten' Bäumen ging ein potentiell geringerer Infektionsdruck aus als von 'ein Jahr toten' Eichen. Im Laufe des Verrottungsprozesses verringert sich diese Gefahr noch weiter, da die Holzfeuchte weiter abnimmt und die Lebendholzbesiedler keine Nahrungsgrundlage mehr vorfinden. Besonders die Gefahr des Neubefalls durch Agrilus von mindestens zweijährig toten Bäumen besteht kaum, weil zumindest die Larven der ersten Stadien des Prachtkäfers auf lebendes Gewebe angewiesen sind.