| Summary: | Coordenação de Aperfeiçoamento de Pessoal de Nível Superior === Studies of biodiversity surveys and habitat requirements are essential in landscapes threatened by
anthropogenic conversion, such as those that make up the Pampa biome. In the present study we
determined the spatial distribution of richness of anurans at the Área de Proteção Ambiental (APA)
do Ibirapuitã, the largest protected federal area within the Pampa biome in Brazil. Thus we: (1)
describe the composition of anuran community regarding species richness, abundance, constancy of
occurrence and reproductive modes; (2) compare the frogs composition with other localities of
grassland southernmost of South America; (3) tested whether local variables of waterbodies, space
and landscape are determinants of species richness, and (4) tested whether environmental
heterogeneity influences the structure of anuran community. Sampling was carried from October to
November 2012 and at November 2013, the searching at breeding sites method, tadpole collecting
and examination of specimens housed in herpetological collections. A total of 64 waterbodies (40
ponds and 24 streams) were sampled for the anuran amphibians, as well as were recorded
environmental descriptors in three scales: local, space, and landscape. We recorded the occurrence
of 33 anuran species at the APA Ibirapuitã. The registered anurans are typical of open areas, and at
least 10% of them are restricted of the grassland areas to the subtropical region of South America,
including two endangered species at the global and state levels. Pseudopaludicola falcipes was the
most abundant species and Hypsiboas pulchellus was the species most frequently recorded. Five
reproductive modes were recorded, and the deposition and the development of exotrophic tadpoles
in lentic waterbodies was the most common mode (57.5%). Cluster analysis revealed five groups
with more than 50% similarity, whose structure was influenced by geographic distance, but can be
partially interpreted by regional peculiarities. We used generalized regression models considering
the set of descriptors as predictors of anuran species richness. Subsequently, we use a partition of
variance to evaluate the independent and shared explicability between different sets of predictors.
Finally, we use a Canonical Redundancy Analysis to explore the role of environmental descriptors
on the species abundance of frogs in ponds and streams. The richness in ponds was influenced by
the local variable representing the area of waterbodies. Already the abundance was correlated with
the percentage of vegetation on the shores and the water temperature. In streams, the species
richness of anurans was correlated with a local variable (number of strata of emergent vegetation)
and a landscape variable (distance in relation to human residences). Species abundance was
affected by higher vegetation strata (> 200 cm) on the shores and by water electrical conductivity.
The combined contribution of local and landscape variables have important implications for
understanding how amphibians are distributed in the grassland environment. Our work shows the
importance of conserving grassland biomes which are increasingly threatened by human activities. === Studies of biodiversity surveys and habitat requirements are essential in landscapes threatened by
anthropogenic conversion, such as those that make up the Pampa biome. In the present study we
determined the spatial distribution of richness of anurans at the Área de Proteção Ambiental (APA)
do Ibirapuitã, the largest protected federal area within the Pampa biome in Brazil. Thus we: (1)
describe the composition of anuran community regarding species richness, abundance, constancy of
occurrence and reproductive modes; (2) compare the frogs composition with other localities of
grassland southernmost of South America; (3) tested whether local variables of waterbodies, space
and landscape are determinants of species richness, and (4) tested whether environmental
heterogeneity influences the structure of anuran community. Sampling was carried from October to
November 2012 and at November 2013, the searching at breeding sites method, tadpole collecting
and examination of specimens housed in herpetological collections. A total of 64 waterbodies (40
ponds and 24 streams) were sampled for the anuran amphibians, as well as were recorded
environmental descriptors in three scales: local, space, and landscape. We recorded the occurrence
of 33 anuran species at the APA Ibirapuitã. The registered anurans are typical of open areas, and at
least 10% of them are restricted of the grassland areas to the subtropical region of South America,
including two endangered species at the global and state levels. Pseudopaludicola falcipes was the
most abundant species and Hypsiboas pulchellus was the species most frequently recorded. Five
reproductive modes were recorded, and the deposition and the development of exotrophic tadpoles
in lentic waterbodies was the most common mode (57.5%). Cluster analysis revealed five groups
with more than 50% similarity, whose structure was influenced by geographic distance, but can be
partially interpreted by regional peculiarities. We used generalized regression models considering
the set of descriptors as predictors of anuran species richness. Subsequently, we use a partition of
variance to evaluate the independent and shared explicability between different sets of predictors.
Finally, we use a Canonical Redundancy Analysis to explore the role of environmental descriptors
on the species abundance of frogs in ponds and streams. The richness in ponds was influenced by
the local variable representing the area of waterbodies. Already the abundance was correlated with
the percentage of vegetation on the shores and the water temperature. In streams, the species
richness of anurans was correlated with a local variable (number of strata of emergent vegetation)
and a landscape variable (distance in relation to human residences). Species abundance was
affected by higher vegetation strata (> 200 cm) on the shores and by water electrical conductivity.
The combined contribution of local and landscape variables have important implications for
understanding how amphibians are distributed in the grassland environment. Our work shows the
importance of conserving grassland biomes which are increasingly threatened by human activities.
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