The destruction of wetlands due to afforestation areas is a common activity in temperate and subtropical regions in Southern America. The expansion of pine in the Coastal Plain of Southern Brazil is out of control and its impacts on aquatic biodiversity are little known. We tested the following hypotheses: the pine occurrence diminishes the anuran richness and abundance in ponds and it changes the anuran composition; the beta-diversity between pine and native grassland matrix ponds (natural ponds) is determined mainly by nestedness. Sampling was carried out from 2007 to 2009 in five ponds in pine invasion matrix and five ponds in native grassland matrix. The natural ponds showed a greater richness of tadpoles (10 species) than pine ponds (5 species). The mean richness of adults was higher in natural ponds than pine ponds throughout the entire study. The species composition was different between natural and pine ponds, for both adults and tadpoles. Comparing natural ponds with each other and the pine ponds with each other, our results showed that neither nestedness nor turnover was determinant for beta-diversity. However, when natural ponds were compared with pine ones, we found that the contribution of nestedness was higher for the anurans beta-diversity than turnover. Increases in the nestedness mechanism indicated that the pine occurrence results in species loss in Southern Brazil ponds. Since 90% of its wetland has been already affected, the removal of Pinus in the conservation areas in southern Brazil is important to minimize their impacts on aquatic biodiversity.

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There is a great need to understand the effects of man‐made land transformation on freshwater biodiversity, because agricultural landscapes provide habitat for many aquatic and semi‐aquatic organisms. However, not all forms of land use are equal in their capacity to support wildlife. Cattle grazing leads to a change in pasture vegetation structure, whereas conversion to commercial crop‐based agriculture promotes structural and chemical degradation of the ecosystem. From 2010 to 2012, in the Pampa biome, southern Brazil, we modelled anuran occupancy for 39 farmland ponds. Specifically, we determined detection probabilities associated with survey‐ and pond‐specific variables and examined tadpole occupancy in relation to land use in southern Brazil. We recorded eleven anuran species, but only five were detected at levels suitable for occupancy modelling. Species detectability varied with water temperature, extent of floating macrophyte cover, and sampling date. For three species, detection‐adjusted occupancy models indicated a relationship between occupancy and agricultural activities and/or livestock management. Agriculture areas negatively affected occupancy by Odontophrynus americanus and Physalaemus gracilis. The presence of livestock within a 500 m radius positively affected pond occupancy by Hypsiboas pulchellus. Other species were negatively associated with pond area or fish presence. Our results demonstrate that traditional extensive livestock farming can provide a buffer that protects freshwater environments, because it did not greatly modify the grassland matrix. We argue that further species‐based approaches will be critical for developing effective conservation strategies for anurans, particularly in the context of the expanding rice production/exotic forests in southern Brazil.

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Segregated species co-occurrence and nestedness are two ecological patterns used to measure assemblage structure. We investigated species co-occurrence and nestedness patterns in assemblages of tadpoles and adult anurans in 30 coastal ponds in southern Brazil. Ponds varied in hydroperiod and were classified as temporary or permanent. We explored whether co-occurrence or nestedness varied among ponds in each hydroperiod. Species co-occurrence patterns were analyzed using the C-score index and three null models. In order to quantify nestedness, we used the nestedness metric based on overlap and decreasing fill (NODF). We found seventeen anuran species; however, only 13 species were observed in breeding activity, and 11 species were observed as tadpoles. The co-occurrence and nestedness analyses showed that anuran assemblages exhibit non-random patterns that were generally contingent on the hydroperiod and pond area. Only species in non-breeding adult anurans assemblages showed significant segregation when randomizations were weighted by pond area and the pattern was similar among hydroperiods. Tadpole assemblages of permanent ponds showed an aggregated co-occurrence in weighted-fixed model. In temporary ponds, NODF showed that anuran assemblages were significantly nestedness in all three phases of life cycle. We obtained contrasting results depending on the hydroperiod. These results support the hypothesis that habitat nestedness, due to hydroperiod, might be an important factor structuring anuran assemblages along the different phases of their life cycle.

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