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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We investigated landscape structure and spatialpatterns of natural grasslands and Atlantic Forests in southern Brazil in 1984Brazil in , 1994Brazil in , and 2005. The studied region is a highland grassland disjunct region (campos de cima da serra) surrounded by forests. We asked: (a) was there an intensification of habitat loss, fragmentation, and isolation of the Atlantic forest or grassland, within the highland ecotonalzone? (b) What was the degree ofconnectivity/isolation of the patches? (c) Was there any pattern of grassland loss related to moisture/microtopography? (d) Did agroeconomic activities influence landscape patterns and land use change? We analyzed Landsat remotely sensed information to characterize the land use and land cover, also considering subdivision into eight agroeconomicregions. Results showed that the area occupied by agriculture suffered a strong expansion along with exotic tree plantations, at the expense of grasslands, which suffered marked loss and fragmentation. Grassland destruction was biased towards humid areas in valleys between relief undulations. Forests expanded as a network of small patches in close contact with other land uses. Land cover differed significantly among agroeconomic regions, suggesting that conservation measures need to contemplate both forest and grassland ecosystems and socioeconomic distinctions as well.Keywords: Araucaria forest, fragmentation, Pampa. ResumoInvestigamos a estrutura da paisagem e padrões espaciais de campos nativos e de florestas Atlânticas no sul do Brasil em 1984, 1994 e 2005. A região estudada é um enclavede campo cercado por florestas. Perguntamos: (a) houve intensificação da perda de habitat, fragmentação e isolamento da floresta Atlântica ou do campo? (b) Qual foi o grau de conectividade/isolamento dos fragmentos? (c) Houve algum padrão de perda de campo relacionada à umidade/microtopografia? (d) O padrão de atividades agroeconômicas influencia a estrutura da paisagem e mudanças no uso do solo? Analisamos imagens Landsat de sensoriamento remoto para caracterizar o uso e cobertura do solo, considerando também a subdivisão da paisagem em oito regiões agroeconômicas. Os resultados mostraram que a área ocupada pela agricultura sofreu forte expansão, juntamente com plantações de árvores exóticas, em detrimento do campo, que sofreu perda e fragmentação acentuada. A destruição do campo foi mais acentuada em áreas úmidas situadas em vales entre ondulações do terreno. As florestas sofreram expansão como uma rede de pequenas manchas em estreito contato com outros usos do solo. A cobertura do solo diferiu significativamente entre as regiões agroeconômicas, sugerindo que medidas de conservação precisam contemplar ambos os ecossistemas, assim como distinções socioeconômicas.Palavras-chave: floresta com araucárias, fragmentação, Pampa.

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