Influência da estrutura do habitat e da matriz sobre a assembleia de anfíbios em uma paisagem naturalmente fragmentada

• Ano de defesa: 2014
• Autor(a) principal: Barreto, Débora Soares
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Mato Grosso; Brasil; Instituto de Biociências (IB); UFMT CUC - Cuiabá; Programa de Pós-Graduação em Ecologia e Conservação da Biodiversidade
• Palavras-chave em Português: Pantanal brasileiro; Paisagem; Composição; Anuros; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA; Brazilian Pantanal; Landscape; Composition; Anurans
• Link de acesso: http://ri.ufmt.br/handle/1/660

Habitat characteristics are predictors of the diversity and distribution of amphibian species. In fragmented landscapes, both characteristics of the patchy habitats and of the surrounding matrix might influence the composition of species. In central-western Brazil, earthmound fields can be considered a naturally fragmented landscape for amphibians. Earthmounds – small terrain elevations not subject to floods, although situated in seasonally flooded areas – can be treated as ecological islands. The aim of the present study was to evaluate how the anuran assemblage in earthmound fields is influenced by earthmound physical structure, connectivity and by the surrounding matrix. The study was conducted in the northern portion of the Brazilian Pantanal, in a region called Pirizal, municipality of Nossa Senhora do Livramento, Mato Grosso. Anurans were sampled during three expeditions of eight days each, in a total of 15 earthmounds, by using pitfall traps with drift fences. To characterize the physical structure of the earthmounds was measured: perimeter of patches of terrestrial bromeliads, total area of fallen logs, perimeter of the base of termite mounds, height of the earthmound, and soil texture. To characterize the connectivity and physical structure of the surrounding matrix, for each earthmound was counted the number of neighboring earthmounds, and estimated its mean distance for neighboring earthmounds and the sum of the perimeters of these neighboring mounds. The influence of environmental variables on the richness and abundance of amphibians was analyzed using multiple linear regressions. The influence on species composition was analyzed using the Redundancy Analysis (RDA). A total of 1252 anurans were recorded. Leptodactylus fuscus (Leptodactylidae), Pseudopaludicola sp. (Leiuperidae) and Rhinella bergi (Bufonidae) were the most abundant species. The richness and abundance of amphibians were not influenced by environmental variables. Therefore, local variations in the richness and abundance of amphibian species cannot be attributed neither to the physical structure of the earthmounds, nor to the connectivity and surrounding matrix. However, nearly 47% of the variation in species composition was explained by environmental variables related to the matrix: sum of the perimeters of neighboring mounds. The latter descriptor refers to the vegetation cover pattern of the matrix, and recorded effects reflect the fact that some species of frogs were more associated with forested habitats, while others, to more open habitats. Leptodactylus elenae and Pseudopaludicola mystacalis, for example, were more abundant in earthmounds amidst a matrix presenting a higher sum of perimeters of neighboring mounds, while Leptodactylus labyrinthicus and Rhinella bergi were more abundant in earthmounds amidst a matrix with the lowest values. The results indicate that anurans are sensitive to changes in fragmented environments, in which each species responds to variations according to their needs and also according to the availability of resources necessary for their survival. Moreover, characteristics and integrity of the matrix where earthmounds are inserted may have greater importance to maintain species composition than structural characteristics of the earthmounds themselves.