Publicação
Os efeitos da intensificação agrícola na comunidade de aves das estepes cerealíferas
| Resumo: | This study evaluates the agricultural intensification effects on steppe bird populations of cereal fields and fallows. Through the analysis of landscape dynamics between 2002–2011, a gradient of agricultural intensification was identified in selected areas of Baixo Alentejo. In cereal fields, total bird abundance of steppe and resident birds decreased along the intensification gradient. During the breeding season, this trend should be related to an increase in height and density of vegetation structure in intensive areas. Food availability is not influenced by intensification. In extensive areas, the bird abundance is influenced by differences associated to the type of cereal and vegetation structure. In fallows, the abundance of steppe and resident birds is affected by intensification. Wintering and breeding species are influenced by fallow age and livestock presence. The multi-scale analysis of local management and landscape composition effects on steppe bird community in cereal fields showed that local component is more important in winter. In fallows, both components are equally important for steppe bird community. Between-year variations (2002-2008) in Tetrax tetrax population densities were shown to be influenced by agricultural intensification and rainfall |
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| Autores principais: | Delgado, Ana Margarida dos Santos |
| Assunto: | steppe bird population agricultural intensification landscape dynamics cereal steppes Tetrax tetrax fallows cereal fields vegetation structure food availability inter-anual variations |
| Ano: | 2013 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | português |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | This study evaluates the agricultural intensification effects on steppe bird populations of cereal fields and fallows. Through the analysis of landscape dynamics between 2002–2011, a gradient of agricultural intensification was identified in selected areas of Baixo Alentejo. In cereal fields, total bird abundance of steppe and resident birds decreased along the intensification gradient. During the breeding season, this trend should be related to an increase in height and density of vegetation structure in intensive areas. Food availability is not influenced by intensification. In extensive areas, the bird abundance is influenced by differences associated to the type of cereal and vegetation structure. In fallows, the abundance of steppe and resident birds is affected by intensification. Wintering and breeding species are influenced by fallow age and livestock presence. The multi-scale analysis of local management and landscape composition effects on steppe bird community in cereal fields showed that local component is more important in winter. In fallows, both components are equally important for steppe bird community. Between-year variations (2002-2008) in Tetrax tetrax population densities were shown to be influenced by agricultural intensification and rainfall |
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