775 resultados para Pastagem degradada


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Over the past few years, the area of planted forests has expanded considerably in Brazil, reaching a level of 6.3 million hectares, which represents approximately 0.7% of the country, mainly with some species of the Eucalyptus genus. However, due to the global concern with biological invasions by exotic species, risk assessment is necessary to evaluate the potential of Eucalyptus species escaping cultivated stands and invading surrounding native ecosystems. Seedlings by natural regeneration from Eucalyptus grandis and E. urophylla, pure and hybrids between the two species were evaluated, by assessing natural regeneration of Eucalyptus in 18 sites located in Brazilian states with plantation forest tradition (Minas Gerais, São Paulo, Rio Grande do Sul and Espírito Santo). Sample plots were installed in the planted stands, along forest roads and in a nearby pasture or native vegetation.,at different distances from the Eucalyptus stands. Regeneration of Eucalyptus was not recorded in 90% of the plots installed outside the eucalipt stands. However, seedlings of eucalypts were observed in 29% of the plots within the commercial stands (mean density of 37 seedlings per hectare) and 40% of the plots located along forest roads (157 seedlings per hectare on average), but no adult plants by natural regeneration were found. The seedlings of eucalypt species studied rarely were found beyond the limits of the cultivated areas. In the planted stands or along forest roads, eucalypts can germinate, but the seedlings apparently do not establish. So the potential for invasion by seeds produced in commercial plantations of Eucalyptus is low.

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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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The aim of this work is to discriminate vegetation classes throught remote sensing images from the satellite CBERS-2, related to winter and summer seasons in the Campos Gerais region Paraná State, Brazil. The vegetation cover of the region presents different kinds of vegetations: summer and winter cultures, reforestation areas, natural areas and pasture. Supervised classification techniques like Maximum Likelihood Classifier (MLC) and Decision Tree were evaluated, considering a set of attributes from images, composed by bands of the CCD sensor (1, 2, 3, 4), vegetation indices (CTVI, DVI, GEMI, NDVI, SR, SAVI, TVI), mixture models (soil, shadow, vegetation) and the two first main components. The evaluation of the classifications accuracy was made using the classification error matrix and the kappa coefficient. It was defined a high discriminatory level during the classes definition, in order to allow separation of different kinds of winter and summer crops. The classification accuracy by decision tree was 94.5% and the kappa coefficient was 0.9389 for the scene 157/128. For the scene 158/127, the values were 88% and 0.8667, respectively. The classification accuracy by MLC was 84.86% and the kappa coefficient was 0.8099 for the scene 157/128. For the scene 158/127, the values were 77.90% and 0.7476, respectively. The results showed a better performance of the Decision Tree classifier than MLC, especially to the classes related to cultivated crops, indicating the use of the Decision Tree classifier to the vegetation cover mapping including different kinds of crops.

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This study was conducted at University of Marília, São Paulo State, Brazil, aiming to determine the phase of intake transition between exclusively liquid diet (milk) and diet based on milk, grass and/or ration by lambs by δ13C technique. Six Suffolk crossbreeding lambs were distributed in a totally random design (3x2), with two experimental groups and three replications. At the first one, lambs were penned and sucked milk from dams fed with C4 diet. besides, they had access to C3 ration in creep feeding, since their birth. At the second group, lambs were kept on a paddock with Tifton – 85 grass (C4 photosynthetic way) as well as their dams and had access to C3 ration in creep feeding, since their birth. The C3 ration contained soybean meal, ground oat grains, lucerne hay and also mineral salt. The penned lambs’ ration consumption overcame the milk intake at 30-35 days after birth; however, grazing lambs ingested more milk and pasture than ration until 40 days after birth. The δ 13C technique was considered effective on studies of lambs feeding behavior.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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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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Pós-graduação em Geografia - IGCE

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Pós-graduação em Agronomia - FEIS

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Pós-graduação em Zootecnia - FCAV

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edge effect. Thus, under the influence of the adjacent matrix, fragments undergo microclimatic alterations that accentuate changes in species composition and community structure. In order to better understand edge and matrix effects on the richness and abundance of edaphic arthropods, this study assessed: (a) the difference between habitat (fragment) and non-habitat (matrix); (b) whether there is a continuous interior-edge-matrix gradient; and (c) the difference between matrices for arthropod orders richness and abundance. We selected 15 landscapes, 5 of which contained a cerrado fragment surrounded by sugarcane cultivation, 5 with a cerrado fragment within eucalyptus and 5 with a cerrado fragment within pasture. In each landscape the soil fauna was collected along with the soil and then extracted with the aid of the modified Berlese-Tullgren funnel. We chose the orders Coleoptera, Collembola, Mesostigmata and Oribatida for analysis, and after separation of the individuals we used model selection analysis via AIC. The model type fragment x matrix was the most likely to explain richness, total and relative abundances of the four orders (wAICc between 0,6623 and 1,0). The model of edge distance (edge effect) was plausible to total abundance and relative abundance of Mesostigmata order (wAICc=0,2717 and 0,186). Local environmental variables (soil texture, temperature and relative humidity), and fragment size were also measured to avoid confounding factors and were not presented as plausible models to explain the patterns. So edaphic arthropods, despite protecting themselves under the ground, are extremely sensitive to fragmentation, even with the replacement of natural habitat by agricultural use, such as sugarcane, pasture and eucalyptus. This group should be studied environmental impact assessments because provides important ecosystem se ravincde s inacnludd eisd ainn efficient bio-indicator

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Novas pesquisas apontam que as interações positivas e o processo de facilitação sobre a comunidade tem fornecido importantes conhecimentos sobre a ecologia de diversas espécies no mundo. Existe uma carência de informações sobre quais as espécies interferem nos mecanismos facilitadores que conduzem a regeneração natural da vegetação e a atual necessidade de identificar estratégias de conservação, manejo sustentável e recuperação ambiental em ambientes tropicais. Este trabalho tem o objetivo de avaliar quais são as espécies arbóreas que facilitam o aumento da riqueza e abundância de outras espécies arbóreas/arbustivas regenerantes sob suas copas numa antiga área de pastagem no Parque Estadual de Porto Ferreira - SP. Foram selecionadas 42 árvores isoladas que foram chamadas de matrizes. Destas matrizes foram feitas 42 parcelas cirulares na qual cada matriz teve duas subparcelas: a Área da Influência (Ai) e a Área do Entorno (Ae), totalizando 84 unidades amostrais. Para cada matriz, nestas unidades amostrais foram incluídos todos os indivíduos arbustivos e arbóreos com altura superior a 1,3 metros de altura. Foram analisadas a florística, fitossociologia e distribuição da abundância das espécies regenerantes. Já para as espécies das matrizes foram analisadas seis diferentes atributos, divididos em dendrométicos e funcionais para entender como elas influênciam a riqueza e abundância das espécies regenerantes. Em Ai e Ae foram indentificados 883 indivíduos distríbuidos em 28 famílias, 49 gêneros, totalizando 64 espécies em uma área total de 3.028 m³. Em Ai foram intentificados 775 inividuos em uma área total de 1.346 m³, com a mesma composição florística citada acima. As espécies Dimorphandra mollis, Qualea grandiflora, Byrsonima intermedia e Aegiphila lhotzkiana são indicadas aqui neste trabalho como as melhores facilitadoras, por serem decíduas e, por possuírem copas amplas...