DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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Resultados da Pesquisa
Item Influence of soil granulometry on average body size in soil ant assemblages : implications for bioindication.(2017) Milanez, Cinthia Borges da Costa; Majer, Jonathan David; Castro, Paulo de Tarso Amorim; Ribeiro, Sérvio PontesSoil granulometric composition can impose constraints on ant species living in ground habitats, being an important factor in defining the habitat templet, which describes how certain animal life histories, including the trait of body size, can be selected. The ant fauna plays a central role in soil formation, and a vast literature describes such influence, but not the converse. Along with termites, worms and other invertebrates, these organisms promote the formation of channels, pores, and aggregates that influence gases and water moving through the soil profile. On the other hand, it is important to understand whether soil traits constrain insect colonization, so we here ask how soil traits can influence niche specificities, which seems to be a neglected ecological issue. A literature search using the key words ‘ants or Formicidae’ and ‘soil structure or pedogenesis’ revealed numerous references dealing with the influence of ants on soil, but not conversely. We here present a novel geomorphologic approach to habitat templets for two distinct riparian Neotropical ecosystems, based on the amalgamation of soil/sediment analysis with ecological processes and ant species biology. We found that predominance of fine grains favoured the preponderance of small ant species at a threshold of <5 mm in body length. Based on this, we propose the use of a quantitative, theoretically sound, statistical approach to bioindication.Item Effect of fire on ant assemblages in brazilian cerrado in areas containing vereda wetlands.(2015) Milanez, Cinthia Borges da Costa; Ribeiro, F. F.; Castro, Paulo de Tarso Amorim; Majer, Jonathan David; Ribeiro, Sérvio PontesCerrado is a biome whose evolution is intimately influenced by constant fire events. Although many species are capable of dealing with this predictable impact, many others may be negatively affected, resulting in community changes after fire. Using ants as bioindicators of changes in biodiversity and environmental conditions, this study evaluated the effects of fire in two Cerrado vegetation types: “cerrado” sensu stricto, a xeric savanna, and wetland “veredas”, a mesic vegetation on floodable soils, where water concentrates and ultimately flows towards rivers. We examined the effects of fire on both habitats in two independent sites, but with special consideration to the wetlands, which are not fully adapted to fire. Ant sampling was conducted twice before and twice after a fire event, using 288 baits and 416 pitfall traps (soil and arboreal), and 16 hand collections along three random replicate transects per area. Ant species richness and abundance were resilient to fire, and exhibited a remarkably consistent seasonal variation at unburned and burned sites. On the other hand, the fire markedly changed the ant species composition. In the wetlands, the fire spread underground due to the high concentration of peat. The impact on ant assemblages was substantial and visually perceptible for some species like Camponotus rufipes, which suffered a considerable reduction in the number of individuals after fire in this habitat. In the cerrado, a similar result was observed for Crematogaster nr. obscurata, which disappeared after fire. The wetland vegetation having little adaptation to fire, plus low resilience in the ant community resulted in a severely changed fauna, both in guild predominance and species composition, and return to an original state is uncertain.Item Are ant assemblages of Brazilian veredas characterised by location or habitat type?(2014) Milanez, Cinthia Borges da Costa; Silva, Glênia Lourenço; Castro, Paulo de Tarso Amorim; Majer, Jonathan David; Ribeiro, Sérvio PontesO ecossistema ribeirinho do Cerrado brasileiro, é conhecido como “vereda”, e é formado em solos arenosos com altas concentrações de turfa, além de serem responsáveis pela recarga dos reservatórios dos aquíferos. Atualmente, as veredas estão sob ameaça de várias atividades humanas, especialmente a supressão da vegetação para plantio de Eucalyptus. Apesar de sua importância ecológica e elevado valor na conservação, pouco se sabe sobre os efeitos das perturbações humanas sobre a comunidade de animais. Para avaliar como que habitats em diferentes veredas e as plantações circundantes afetam a assembleia de formigas, foram selecionadas quatro “veredas” independentes, sendo duas impactadas pela monocultura de eucalipto (uma jovem e uma madura) e duas controles com a planície de inundação circundada por vegetação de cerrado. A coleta das formigas foi realizada em Maio de 2010 (estação seca) por meio de três métodos complementares, iscas atrativas, armadilhas de pitfall e coleta direta, no habitat de planície alagada, e na área circundante. Foi amostrado um total de 7.575 formigas, pertencentes a sete subfamílias, 32 gêneros e 124 espécies. A riqueza e abundância de formigas não diferiram entre as localidades “veredas”, mas sim entre os habitats. Quando impactados pela monocultura, a abundância e a riqueza diminuem nas planícies de inundação, mas os habitats de cerrado foram menos afetados. As plantações de eucalipto têm sua composição de espécies de formigas definida pela alta dominância de Pheidole sp. e Solenopsis invicta, enquanto os habitats naturais foram definidos por espécies deCamponotus e Crematogaster. Atta sexdens foi estritamente relacionada à habitats nativos de “veredas” preservadas. A monocultura de eucalipto requer grandes quantidades de água nos estágios iniciais, o que pode ter provocado a queda no nível do lençol freático nas planícies alagadas, permitindo a colonização deste habitat por espécies de formigas de hábitos hipógeos, como Labidus praedator.