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Universidade de Brasília (2007)

Efeitos do fogo sobre a taxocenose de lagartos em áreas de cerrado sensu stricto no Brasil central

Leite, Davi Lima Pantoja

Titre : Efeitos do fogo sobre a taxocenose de lagartos em áreas de cerrado sensu stricto no Brasil central

Auteur : Leite, Davi Lima Pantoja

Université de soutenance : Universidade de Brasília

Grade : Mestrado em Biologia Animal 2007

The fire is a natural agent of disturbance in tropical savannas, modifying the structure of animal and plant communities and transforming the landscape. As intermediate agent of disturbance the burns can contribute for maintenance of the diversity in the Cerrado. The effects of fire on the structure of lizard assemblages in the Cerrado of Central Brazil had been investigated using pit-fall traps. Throughout the different effects of burning regimes upon lizard richness, abundance and evenness ; and how are the connections between lizard abundance and the changes in habitat characteristics induced by fire. Five plots of Cerrado sensu stricto under different burning regimes were sampled : quadrennial fires, biennial fires at early, modal and late dry-season and the control, without fire. Lizards had been surveyed during five days by month, December of 2005 the November of 2006, totalizing 600 trap*days by plot. The abundance and evenness had been lower under extremer disturbance, in agreement with intermediate disturbance hypothesis in the local level. Such result was conversely for richness contrasts. Lizard species survive well to direct effects off burns but they have varied sensitivity to subsequent effect and under periodic disturbances, evenness must to be much more informative. In addition, It is suggested that high lizard richness can be lead by a combination between niche specializations, competition reduction and predation pressures in the extremities of the disturbance gradient in Cerrado. Fourteen lizard species were surveyed, six shown fire-regimes sensibility and only occurred under a specific treatment (Enyalius aff. bilineatus, Tropidurus torquatus, Polychrus acutirostris, Mabuya guaporicola, Bachia bresslaui, and Tupinambis duseni), but two generalists species (Tr. itambere and Ameiva ameiva) had not occurred only under extreme regimes. Tropidurus itambere and Micrablepharus atticolus had presented strong dominance under more severe regimes and Ma. frenata and Ma. nigropunctata in the absence of the fire. The total abundance of lizards did not vary throughout the year, but higher evenness had been observed in the summer. The effects on the lizard assemblage structure had been significantly related with changes in the habitat structure induced by fire, but they had little relation with the variability of climate parameters throughout the year. Particularities of habitat structure in plots under different fire regimes, and the presence of exclusive species of lizards in each one plot, suggest that if natural burns lead to heterogenic landscape it can either drive to richer lizard fauna in regional context, rather than anthropogenic burns or the complete absence of fire. This pattern must be recurrent in other animal taxa and the anthropogenic fires, with high-frequency and low periodicity as well as the complete suppression of burns must be avoiding. The maintenance of these artificial regimes can drive great loss of local and regional diversity.

Mots clés : Taxocenose Cerrados Diversidade biológica Ecologia Brasil central


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