ResumoO presente trabalho teve por objetivo, quantificar a biomassa e o estoque de nutrientes de um clone de Eucalyptus saligna em quatro idades no município de Telêmaco Borba -PR. O trabalho foi realizado em povoamentos com idades de 1,1; 3,6; 5,5 e 6,7 anos. As árvores foram separadas nos componentes: folhas, galhos, casca e madeira do tronco, coletando-se uma amostra representativa de cada fração. A biomassa total encontrada foi de 37,35; 190,03; 227,12 e 249,49 Mg ha -1 nas idades de 1,1; 3,6; 5,5 e 6,7 anos respectivamente. Os componentes madeira e casca correspondem a 89% da biomassa total de Eucalyptus saligna aos 6,7 anos. No componente folha foi observado a maior concentração de N, P e K. Já os maiores teores de Ca foram registrados nos galhos e casca. Os resultados apontam ainda, elevadas quantidades de nutrientes na biomassa de madeira e casca em todas as idades, principalmente K e Ca.Palavras-chave: biomassa florestal, alocação de nutrientes, silvicultura, eucalipto. AbstractThis study aimed to quantify the biomass and nutrient stocks of a Eucalyptus saligna clone in four ages in the municipality of Telêmaco Borba -PR. The study was conducted in stands with 1.1; 3.6; 5.5 and 6.7 years. The trees were cut and separated into components: leaves, twigs, bark and wood of the trunk, by collecting a representative sample of each component. The total biomass found was 37.35; 190.03; 227.12 and 249.49 Mg ha -1 at the ages of 1.1; 3.6; 5.5 and 6.7 years respectively. The wood and bark components account for 89% of the total biomass of Eucalyptus saligna to 6.7 years. The results show high amounts of nutrients in biomass, especially Ca and K. The component leaves had the highest concentration of N, P and K. The larger Ca concentrations were registered in the branches and bark.Keywords: forest biomass, allocation of nutrients, silviculture, eucalypt. INTRODUÇÃOA demanda por produtos florestais cresce a cada ano e atualmente no cenário socioeconômico brasileiro a silvicultura passou a ter destaque no setor de produção, devido aos seus benefícios econômicos, sociais e ambientais (CORRÊA et al., 2013). Sendo que, um dos principais benefícios do cultivo dos eucaliptos, é oferecer alternativas para o suprimento de madeira, diminuindo, dessa forma, a pressão sobre as florestas nativas, pois mesmo que estas pudessem ser utilizadas de forma sustentável, não seriam suficientes para atender à crescente demanda de madeira, devido às dificuldades técnicas de manejo para que se obtenha a produtividade compatível com as necessidades das empresas (VIERA; SCHUMACHER, 2011).As espécies introduzidas no Brasil como o Eucalyptus saligna, permitem um ciclo de corte relativamente curto e uma alta produtividade, quando comparadas com espécies florestais nativas. Apre-
-The aim of this study was to identify, by multivariate statistical technique, the physic, chemical and biological variables that best characterize the quality of surface waters in two small rural catchments with different land uses (eucalyptus silviculture (SC) vs. pasture and extensive livestock (LC)) located in Rosário do Sul, RS -Brazil. Monitoring was conducted during the months of August 2011 to August 2012 and the following parameters were analyzed: Ca , pH, electrical conductivity, turbidity, alkalinity, suspended and dissolved solids, biochemical oxygen demand , total coliforms, Escherichia coli and temperature, flow and rainfall. Through the use of FA/PCA, it was found that the model best fit to express water quality of in LC that was composed of five factors which account for 83.5% of the total variance, while for SC, four factors accounted for 85.12% of the variance. In LC, the five main factors were, respectively, soluble salts, diffuse pollution, solid, and both anthropogenic and organic factors. In SC, the four factors were namely: soluble salts, mineral, nutritional and diffuse pollution factors. The results of this study showed that by replacing the traditional soil usage (pasture and livestock) with planted forest, diffuse pollution was attenuated but, however, it did not result in major changes in the physical-chemical and biological characteristics of the water. Another point to note is that factorial analysis did not result in a large reduction in the number of variables, once the best model fit occurred with the addition of 15 of 18 analyzed variables (LC) and 17 of 18 analyzed variables (SC).Keywords: Multivariate analysis; Water resources; Silviculture. FATORES INFLUENTES NA QUALIDADE DAS ÁGUAS SUPERFICIAIS 1136Revista Árvore, Viçosa-MG, v.39, n.6, p.1135-1145, 2015 VALENTE, M.L. et al.geral, não implicou grandes alterações nas características físico-químicas e biológicas da água. Outro ponto observado foi que, neste estudo, a análise fatorial não resultou em grande redução no número de variáveis, uma vez que o melhor ajuste do modelo ocorreu com a inclusão de 15 das 18 variáveis analisadas (BC) e de 17 das 18 variáveis analisadas (BE).
Resumo: A serapilheira é a principal via de transferência de nutrientes das plantas para o solo em ecossistemas florestais. Assim, o estudo da produção de serapilheira é fundamental para compreender o funcionamento destes ecossistemas. O presente estudo objetivou a avaliação da produção de serapilheira, a devolução de macronutrientes e a correlação com variáveis climáticas, em um povoamento de Eucalyptus saligna em São Gabriel -Rio Grande do Sul. Foram instaladas 4 parcelas de 23 m x 26 m e em cada uma delas foram distribuídos 4 coletores com 0,5 m 2 de área. Para a quantificação de galhos grossos (diâmetro > 0,5 cm), em cada parcela foram demarcadas três subparcelas de 3 m x 2 m, sobre o solo, delimitadas por uma árvore de diâmetro médio. As amostras foram coletadas quinzenalmente, separadas em galhos grossos, galhos finos (diâmetro < 0,5 cm), folhas e miscelânea, após foram secas em estufa, pesadas, moídas e encaminhadas para análise química, onde foram determinados os teores dos macronutrientes. A produção anual de serapilheira foi de 9,93 Mg ha Litterfall production and return of macronutrients of settlement in a Eucalyptus saligna (F. Muell)Abstract: Litterfall is the mainly route of plant nutrients transfer to the soil in forest ecosystems. Therefore the study of the litterfall is very important fundamental to understanding the functioning of these ecosystems. Given this importance, this study aimed to estimate litter production in Eucalyptus saligna stand, São Gabriel -RS. Were installed 4 plots of 23 m x 26 m in each of these plots, 4 litter collectors. For branches with a diameter bigger than 0.5 cm, in each plot were demarcated aboveground three plots of 3 m x 2 m, bounded by an average diameter tree. Samples were collected fortnightly, sorted into thick branches, twigs (diameter of less than 0.5), leaves and miscellaneous, then were oven dried, weighty, and sent to the chemical analysis where it was determinate the content of macronutrients. During the twelve month period, litter production was 9,93 Mg ha -1 , 54.0% of leaves, 24.7 % thick branches, 11.2 % of miscellaneous and 10.1% of twigs. The overall contribution of macronutrients was 71,56 kg ha -1 of Ca, 45,15 kg ha -1 of N, 38,93 kg ha -1 of K, 17,54 kg ha -1 of Mg, 6,19 kg ha -1 of S and 2,81 kg ha -1 of P.
Intensive management of forest stands can increase biomass production, as well as increase the removal of nutrients from the site. This study therefore sought to simulate different harvest intensities and to calculate the nutrient-use efficiency of Eucalyptus urograndis in different types of soil. The study was carried out in a plantation of seven-year-old hybrid E. urograndis in the city of Telêmaco Borba, Paraná, Brazil. The study site included two sub areas with sandy soil and clayey soil (Cambisols Inceptisol and Ferralsols Oxisols, respectively). Using biomass and nutrients stock data, nutrient removal was simulated under five different harvest scenarios. Nutrient-use efficiency was obtained from the relation between the amount of biomass and nutrients of each tree component. Harvesting the whole tree resulted in the removal of approximately 61% of the nutrients from the site in sandy soil, while in clayey soil 57% of the nutrients were removed. With harvesting of only the commercial stemwood, only 22% of the nutrients were removed from the sandy soil, and 21% from the clayey soil. Stemwood was the component that had the highest nutrient-use efficiency values for all the analyzed nutrients. In conclusion, to achieve nutritional sustainability of E. urograndis stands, the best harvesting system involves the removal of only commercial stemwood. For the production of stemwood, sandy soils have a greater biological efficiency of calcium and magnesium when compared to clayey soil.
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