Papel ecológico do fogo e das saúvas (Atta spp.) na ciclagem de nutrientes e carbono em cerrado

• Ano de defesa: 2007
• Autor(a) principal: Souto, Leandro de Sousa
• Orientador(a): Schoereder, José Henrique
• Banca de defesa: Coracini, Miryan Denise Araújo , Reis Júnior, Ronaldo , Lúcia, Terezinha Maria Castro Della
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Entomologia
• Departamento: Ciência entomológica; Tecnologia entomológica
• País: BR
• Palavras-chave em Português: Cerrado; Solos; Latossolo; Sequestro de carbono; Formigas-cortadeiras; Queimadas
• Palavras-chave em Inglês: Cerrado; Soil; Sink of carbon; Leafcut ant; Forest fire
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/948

In dystrophic environments, as savannas, nutrient cycling is of fundamental importance for maintenance, regulation and development of those habitats. Some factors as seasonal burning and herbivory are considered important in the cycling process, because these factors remove a great amount of biomass, leading to an unbalance between losses and inputs of the system. In this work the effect of a possible antagonistic role of burning and leaf-cutting ants in the nutrient cycling in cerrado was tested. To test this hypothesis, we evaluated the effect of fire and ant nests on the concentration of soil nutrients, root density and nutritional status of herbs and woody plants in both burned and unburned plots of cerrado. We found that fire did not affect nutrient concentration, root density and foliar nutrient contents of woody plants, in comparison with control soil. Fire increased foliar contents of the herb species. Fire did also reduce concentrations of soil macronutrients in ant nests. In contrast, Atta laevigata nests increased foliar nutrient content of surrounding herbs and woody plants and increased up to 60% root density in both plots. In the unburned plot ant nests also increased the nutrient stocks principally at intermediate depths (subsoil). The low concentration of nutrients in ant nests from burned plot could be due to the high nutrient assimilation during post-fire recover. The antagonistic role of Atta nests and fire on nutrient cycling was not confirmed. Although frequent burning resulted in some significant increase in the nutrient content of herbs, it also resulted in some significant losses. On the other hand, ant nests may represent an important source of nutrients for plants on the nutrient-depleted cerrado soils, and may accelerate vegetation recovery after burning. Leaf-cutting ants play an important role in biogeochemical cycling in the cerrado ecosystem through concentrating nutrients in the subsoil and affecting nutrient content of surrounding plants. Due to the activity of ants, their nests might be an important biological sink of carbon, acting in the carbon sequestration of Neotropical forests and savannas.