775 resultados para Pastagem degradada
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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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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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As variações da temperatura e do fluxo de calor em solos sob a floresta nativa de Caxiuanã e uma pastagem natural da Ilha do Marajó, foram monitoradas continuamente no período de dezembro de 2001 a fevereiro de 2005. O objetivo foi comparar as respostas térmicas ao aquecimento diário, dos solos desses dois tipos de ecossistemas existentes no leste da Amazônia, para subsidiar modelos regionais de clima e avaliação dos efeitos de desmatamento. Além das medidas de campo das variáveis acima citadas, em três níveis até a profundidade de 0,5 m, esse trabalho apresenta estimativas de fluxo de calor e propriedades dos solos, tais como: difusividade e condutividade térmicas, profundidade de amortecimento e velocidade de propagação do pulso de aquecimento diário, determinados por métodos analíticos. Os resultados mostraram o contraste sazonal e outras diferenças significativas de respostas entre os dois sítios estudados, destacando o papel do conteúdo de água nos perfis térmicos verticais em cada tipo de solo. O ajuste obtido entre as medidas e os valores calculados das variáveis, indica a possibilidade de generalização dos resultados para outros sítios de ecossistemas similares na Amazônia.
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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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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Zootecnia - FMVZ
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O presente estudo avaliou a fauna de Arctiinae numa área de pastagem na Amazônia Oriental em Altamira-Pará, por meio de armadilha luminosa, com duas capturas mensais noturnas a cada fase da lua nova, no período de dezembro de 2008 a novembro de 2010. Foram avaliados os seguintes parâmetros: riqueza, abundância, dominância, constância, índices de diversidade e uniformidade de Shannon (H' e E') e Brillouin (H e E), dominância de Berger-Parker (BP). As estimativas de riqueza foram feitas através dos procedimentos não paramétricos, "Bootstrap", "Chao1", "Chao2", "Jackknife1", "Jackknife2", e "Michaelis-Mentem". Foram capturados 910 exemplares pertencentes a 85 espécies de Arctiinae. Os valores dos parâmetros analisados para o período total foram: H'= 2,58, E'= 0,581, H= 2,45, E= 0,576 e BP= 0,433. Para os anos, tanto a riqueza quanto a abundância foi maior em 2009-2010. A diversidade e uniformidade de Shannon e Brillouin foram maiores para o ano de 2008-2009. Os estimadores previram um aumento entre 18,8% e 85,9 % na riqueza de espécies.
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The knowledge on spatial distribution of soil properties by means of geostatistics is important as an indicator for a better soil use and management. This study aimed at evaluating the spatial distribution of soil chemical properties, in a forest and pasture area in Manicoré, Amazonas State, Brazil. Grids with 70.00 m x 70.00 m, with regular spacing of 10.00 m x 10.00 m, totaling 64 points, were established, and then soil samples were collected at the depths of 0.0-0.20 m and 0.40-0.60 m and had their chemical properties determined. Data were analyzed by using descriptive statistics and geostatistics, and the sampling density analysis was based on the coefficient of variation and semivariograms range. The mean and median values were adjusted to the closest values, indicating normal distribution, while the spherical, exponential and gaussian models were adjusted to the soil chemical properties. It was concluded that the geostatistics provided adequate information for understanding the spatial distribution. The forest area showed a higher spatial continuity and the pasture area a lower sampling density. The chemical properties showed differences in the spatial variability, while the range represented better the estimates for sampling density and spacing, in the forest and pasture area.
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The use of geostatistical techniques allows detection of the existence of dependence and the spatial distribution of soil properties, thus constituting an important tool in the analysis and detailed description of the behavior of soil physical properties. The aim of the present study was to use geostatistics in assessment of physical properties in a Latossolo (Oxisol) dystrophic under native forest and pasture in the Amazon region of Manicore. Grids with of 70 x 70 m were established in native forest and pasture, and points were marked in these grids spaced at every 10 m, for a total of 64 points. These points were then georeferenced and in each one, soil samples (128) were collected at the depths of 0.00-0.20 and 0.40-0.60 m for a survey of their physical properties. These grids are parallel at a distance of 100 m from one another. The following determinations were made: texture, bulk density and particle density, macroporosity, microporosity, total porosity and aggregate stability in water. After tabulating the data, descriptive statistical analysis and geostatistical analysis were performed. The pasture had a slight variation in its physical properties in relation to native forest, with a high coefficient of variation and weak spatial dependence. The scaled semivariograms were able to satisfactorily reproduce the spatial behavior of the properties in the same pattern as the individual semivariograms, and the use of the parameter range of the semivariogram was efficient for determining the optimal sampling density for the environments under study. The geostatistical results indicate that the removal of native forest for establishing pasture altered the natural variability of the physical properties.
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This trial was carried out to study the effects of supplementation level on performance of steers from different genetic groups (Nellore x Red Angus (NR), Nellore (NL) and Holstein crossbred (MH), and three experimental periods. The performance data for first period were analyzed according to randomized block (RB) design, with 3 treatments ((NR, NL and MH)) and 3 blocks. In second period, the RB design used with 3 x 3 factorial design, and 3 blocks. Factor A determined the group (NL and MH) and factor B the supplementation levels (0.2, 0.6 and 1% LW). In third period, the data were evaluated according to completely randomized design, with 2 x 3 factorial design. Factor A determined the group and factor B, three levels of supplementation. In the first, higher weight gain (p < 0.05) was observed for NR (0.79 kg day-1) compared to MH and NL (0.73 and 0.61 kg day-1). The concentrate intake varied for N. NR showed higher (p < 0.05) WG (0.91 kg day-1) compared to NL (0.75 kg day-1) and MH (0.76 kg day-1). The levels of supplements influenced (p < 0.05) WG (0.68, 0.81 and 0.92 referring to levels of 0.2, 0.6 and 1.0% LW). In third period, MH presented greater WG < 0.05) (0.895 kg day-1). No difference was verified on animals with 0.8 and 1.2% LW, with WG of 0.92 and 0.82 kg day-1.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Zootecnia - FCAV