Navegando por Autor "Bustamante, Mercedes Maria da Cunha"
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Item Competitividade de espécies arbóreas juvenis e gramíneas do Cerrado e suas respostas ao aumento da disponibilidade de nitrogênio.(2009) Kozovits, Alessandra Rodrigues; Bustamante, Mercedes Maria da Cunha; Soares, N. C.; Silva, Maria Regina Silveira Sartori da; Silva, D. A. S.Item Deep into the mud : ecological and socio-economic impacts of the dam breach in Mariana, Brazil.(2016) Fernandes, Geraldo Wilson Afonso; Goulart, Fernando F.; Ranieri, Bernardo Dourado; Coelho, Marcel Serra; Dales, Kirsten; Boesche, Nina; Bustamante, Mercedes Maria da Cunha; Carvalho, Felipe A.; Carvalho, Daniel Cardoso de; Dirzo, Rodolfo; Fernandes, Stephannie; Galetti Júnior, Pedro Manoel; Garcia Millan, Virginia Elena; Mielke, Christian; Ramirez Malaver, Jorge Luis; Neves, Ana; Rogass, Christian; Ribeiro, Sérvio Pontes; Scariot, Aldicir; Soares Filho, BritaldoWe review the ecological and socio-economic impacts ofthe catastrophic dam failure in Mariana, Brazil. Tailing management practices by Samarco mining company ultimately caused a dam breach that abruptly discharged between 55 and 62millionm3 of tailings into the Doce River watershed. On November 5th, 2015, a tsunami of slurry engulfed the small district of Bento Rodrigues, loading the Doce River and its estuary with toxic tailings along a 663.2 km trajectory, extending impacts to the Atlantic coast. Acute ecological impacts will adversely affect livelihoods of more than 1 million people in 41 riparian municipalities by reducing local access to fisheries resources, clean water, crop production sites, hydroelectric power generation and raw materials. The threats to riverine human communities are particularly critical for the disadvantaged populations from remote areas that rely on subsistence agriculture and fisheries, and are uniquely vulnerable to long-term heavy metal exposure. At the landscape scale, we predict multiple negative impacts, ranging from alterations of the genetic diversity of fish populations to long-term vegetation loss and poor regeneration in contaminated areas. Consequently, compromised soil stability and runoff control will increase the risk of further geomorphologic disturbance, including landslides, bank failure and mass movements. We propose spatially explicit long-term monitoring frameworks and priority mitigation measures to cope with acute and chronic risks. We posit that, from a national perspective, disastrous impacts like that of Doce River may become more frequent, given the recent regulatory changes that undermine both institutional governance structures and enforcement of environmental regulation.Item Diversity of shrub tree layer, leaf litter decomposition and N release in a Brazilian Cerrado under N, P and N plus P additions.(2011) Jacobson, Tamiel Khan Baiocchi; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra RodriguesThis study investigated changes in diversity of shrub-tree layer, leaf decomposition rates, nutrient release and soil NO fluxes of a Brazilian savanna (cerrado sensustricto) under N, P and N plus P additions. Simultaneous addition of N and P affected density, dominance, richness and diversity patterns more significantly than addition of N or P separately. Leaf litter decomposition rates increased in P and NP plots but did not differ in N plots in comparison to control plots. N addition increased N mass loss, while the combined addition of N and P resulted in an immobilization of N in leaf litter. Soil NO emissions were also higher when N was applied without P. The results indicate that if the availability of P is not increased proportionally to the availability of N, the losses of N are intensified.Item Effects of nutrient additions on plant biomass and diversity of the herbaceous-subshrub layer of a Brazilian savanna (Cerrado).(2012) Bustamante, Mercedes Maria da Cunha; Brito, Darlan Quinta de; Kozovits, Alessandra Rodrigues; Luedemann, Gustavo; Mello, Thiago de Roure Bandeira de; Pinto, Alexandre de Siqueira; Munhoz, Cássia Beatriz Rodrigues; Takahashi, Frederico Scherr CaldeiraThe Brazilian Cerrado is a diversity hotspot due to its high level of endemism and rapid loss of habitats. It is estimated that the number of herbaceous species is four times higher than that of woody species. Increasing levels of nitrogen additions to natural ecosystems have been indicated as a determinant of biodiversity loss. We investigated the effects of nutrient additions on the productivity (aboveground and belowground) and on diversity of the herbaceoussubshrub layer of a Brazilian savanna (cerrado stricto sensu). The experiment was carried out in the IBGE Ecological Reserve, near Brası´lia, Brazil. Between 1998 and 2006, N, P, N plus P, or Ca were applied to sixteen 225 m2 plots, arranged in a completely randomized design. Aboveground biomass was compared 1 year after the first fertilization and 10 years later. Floristic diversity was significantly different (P\0.01) between the treatments. The highest and lowest species richness were presented in control and NP, respectively. The addition of P alone or in combination with N induced invasion by Melinis minutiflora (exotic C4 grass). The aboveground biomass of this species was higher in NP and P plots. In the N treatment, Echinolaena inflexa (native C3 grass) presented elevated cover and biomass but M. minutiflora was absent. The invasion by alien species resulted in negative impacts on native grass species. Besides changes in aboveground biomass, addition of N and P also led, although to a lesser extent, to changes in the root morphology and biomass, but these responses were modulated by seasonal variation in soil moisture. The results suggest that environmental changes in nutrient availability can lead to important consequences for diversity and functioning of this savanna where the numerous rare species have more chance to persist under dystrophic conditions as some species that tend to be dominant would be less competitive.Item Emissão de óxidos de nitrogênio associada à aplicação de ureia sob plantio convencional e direto.(2006) Carvalho, Arminda Moreira de; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra Rodrigues; Miranda, Leo Nobre de; Vivaldi, Lúcio José; Sousa, Danielle Matias deO objetivo deste trabalho foi avaliar emissões de NO e N2O até cinco dias após a primeira fertilização de cobertura com uréia em milho, em Latossolo Vermelho argiloso distrófico, sob plantio convencional e direto. A adubação de cobertura foi de 60 kg ha-1 de N. O experimento foi conduzido na Embrapa Cerrados, Planaltina, DF, com delineamento de blocos ao acaso, com três repetições, sendo o terceiro cultivo de milho, em rotação com soja. Os fluxos de NO e N2O foram medidos em câmaras de PVC instaladas em cada parcela. Houve emissão alta de NO imediatamente após (5,4 ng N cm-2 h-1) e no terceiro dia (4,8 ng N cm-2 h-1) após aplicação de uréia e irrigação. Um dia após fertilização, a emissão de NO reduziu-se a 1,9 ng N cm-2 h-1, e cinco dias depois, alcançou 1,2 ng N cm-2 h-1. Os fluxos de N2O ficaram abaixo do limite de detecção de 0,6 ng N cm-2 h-1. Não houve diferença significativa entre os plantios convencional e direto quanto à emissão dos óxidos de nitrogênio.Item Fluxo de gases traço, carbono da biomassa microbiana e nitrogênio mineral em solos sob cultivo de feião irrigado e sob vegetação nativa de Cerrado.(2005) Fernandes, Êrika Barretto; Perez, Katia S. S.; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra Rodrigues; Bresolin, JoanaItem Nutrient resorption and patterns of litter production and decomposition in a Neotropical Savanna.(2007) Kozovits, Alessandra Rodrigues; Bustamante, Mercedes Maria da Cunha; Garofalo, Catarina R.; Bucci, Sandra; Franco, Augusto Cesar; Goldstein, Guillermo; Meinze, Frederick C.Item Respiração do solo em resposta à fertilização com N e P e às variações de temperatura e umidade do solo e do ar em uma área de Cerrado senso restrito.(2007) Valim, Eduardo André Ribeiro; Miranda, Viviane Teixeira; Silva, José Salomão Oliveira; Silva, Maria Regina Silveira Sartori da; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra RodriguesItem Soil emissions of NO, N2O and CO2 from croplands in the savanna region of central Brazil.(2011) Cruvinel, Erika Barreto Fernandes; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra Rodrigues; Zepp, Richard G.In the last 40 years, a large area of savanna vegetation in Central Brazil (Cerrado) has been converted to agriculture, with intensive use of fertilizers, irrigation and management practices. Currently, the Cerrado is the main region for beef and grain production in Brazil. However, the consequences of these agricultural practices on NO, N2O and CO2 emissions from soil to atmosphere are still poorly investigated. The objectives of this study were to quantify soil emissions of NO-N,N2O-N andCO2-C in different no-till cultivation systems in comparison with native savanna vegetation. The agricultural areas included: (a) the maize and Brachiaria ruzizienses intercropping system followed by irrigated bean in rotation; (b) soybean followed by natural fallow; and (c) cotton planting over B. ruzizienses straw. The study was performed from August 2003 to October 2005 and fluxes were measured before and after planting, after fertilizations, during the growing season, before and after harvesting. NO-N fluxes in the soybean field were similar to those measured in the native vegetation. In the cornfield, higher NO-N fluxes were measured before planting than after planting and pulses were observed after broadcast fertilizations. During Brachiaria cultivation NO-N fluxes were lower than in native vegetation. In the irrigated area (bean cultivation), NO-N fluxes were also significantly higher after broadcast fertilizations. Most of the soilN2O-N fluxes measured under cultivated and native vegetation were very low (<0.6 ngN2O-Ncm−2 h−1) except during bean cultivation when N2O-N fluxes increased after the first and second broadcast fertilization with irrigation and during nodule senescence in the soybean field. Soil respiration values from the soybean field were similar to those in native vegetation. The CO2-C fluxes during cultivation of maize and irrigated bean were twice as high as in the native vegetation. During bean cultivation with irrigation, an increase in CO2-C fluxes was observed after broadcast fertilization followed by a decrease after the harvest. Significantly lower soil C stocks (0–30cm depth) were determined under no-tillage agricultural systems in comparison with the stocks under savanna vegetation. Fertilizer-induced emission factors of N oxides calculated from the data were lower than those indicated by the IPCC as default.Item Variações sazonais nas concentrações de pigmentos e nutrientes em folhas de espécies de cerrado com diferentes estratégias fenológicas.(2007) Carvalho, Ana Paula Ferreira; Bustamante, Mercedes Maria da Cunha; Kozovits, Alessandra Rodrigues; Asner, Gregory PaulVários estudos têm procurado estabelecer relações entre as condições ambientais e as propriedades foliares. Neste trabalho foram medidas as concentrações de pigmentos (clorofilas a, b, carotenóides e antocianinas), N e P e área foliar específica (AFE) em folhas de seis espécies de cerrado (sendo três decíduas e três sempre-verdes) em dois sítios de cerrado stricto sensu com diferenças de cobertura arbustiva-arbórea e em diferentes períodos: início do período seco (junho), fim da seca (setembro) e início das chuvas (novembro). As concentrações de nutrientes variaram mais em função da fenologia e da sazonalidade do que em relação às diferenças estruturais nos sítios, ao contrário do que foi observado para os pigmentos foliares. Os maiores valores de concentração de clorofilas a e b foram encontrados no início (junho) em relação ao final da seca (setembro) nas duas áreas. Em junho, as concentrações de clorofilas a e b foram maiores na área mais densa enquanto a razão clorofila a/b foi menor. A razão clorofila total/carotenóides também foi significativamente maior no cerrado fechado em relação ao aberto nesse período devido às maiores concentrações de clorofilas no primeiro sítio. Espécies decíduas apresentaram maiores médias de AFE em relação às sempre-verdes, tanto na estação seca como na chuvosa, mas concentrações mais elevadas de N e P foram encontradas em espécies sempre-verdes em relação às decíduas. Nos dois grupos fenológicos, as concentrações foliares de N e P e a razão N:P foram maiores na estação chuvosa (novembro) em relação à estação seca (junho).