Riqueza, diversidade funcional e sazonalidade de aves em uma planície de inundação artificial
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Data
2017-07-31
Autores
Robinson, Vivian [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As áreas úmidas são reconhecidas como prioritárias para a conservação da biodiversidade global e estão entre os ecossistemas mais frágeis e ameaçados do planeta por estarem sujeitos a impactos antrópicos na terra e na água. Estima-se que, no mundo todo, pelo menos 50% destes ambientes tenham sido perdidos nos últimos cem anos. Para São Paulo, os remanescentes da vegetação de várzea, já, ocupavam apenas 0,63% do território estadual em 2001. As várzeas do Tanquã ocorrem no rio Piracicaba em uma planície de inundação cujo pulso de inundação natural foi invertido em relação à sazonalidade de chuvas locais pela construção de uma barragem a jusante. No local ocorrem 94 espécies de aves aquáticas, 16 das quais realizam movimentos migratórios, oito são ameaçadas no estado de São Paulo, quatro são quase ameaçadas e duas não possuem dados suficientes na literatura para concluir seu grau de ameaça. A construção de diversas estruturas para regulação do fluxo d’água está prevista nesta bacia hidrográfica e o manejo correto de áreas impactadas como o Tanquã pode desempenhar um papel importante na conservação das aves. Avaliamos a variação temporal da composição e abundância da comunidade de aves aquáticas de acordo com o nível de água do Tanquã, a partir de censos mensais durante um ano em sete pontos de contagem, a fim de entender como áreas mantidas artificialmente inundadas poderiam sustentar diferentes grupos funcionais de aves, prevenindo futuras perdas de biodiversidade. Discutimos a importância da área como habitat de descanso e reprodução de espécies de aves migratórias e ameaçadas no estado de São Paulo e o risco que esta área corre caso seu regime hídrico seja alterado novamente. O empreendimento “Aproveitamento Múltiplo Santa Maria da Serra” prevê a elevação e estabilização do nível do rio em 6 ou 10 metros do máximo atual, a fim de ampliar a extensão da Hidrovia Tietê-Paraná. Diferentes grupos funcionais de aves aquáticas se relacionaram de formas diferentes com a profundidade do rio, no entanto, como a abundância geral das aves está negativamente correlacionada com o mesmo, essa modificação adicional no pulso de inundação pode fazer com que a área perca sua capacidade de suportar a biodiversidade. Futuros projetos de construção de barragens devem tomar ações como a criação de heterogeneidade de habitat e a manutenção de um pulso de inundação adequado, para transformar ou manter suas áreas de influência como habitats importantes para a comunidade ameaçada de aves aquáticas, contribuindo assim para a sua conservação.
Wetlands are globally recognized as priorities for biodiversity conservation and are among the planet's most fragile and threatened ecosystems, as they are subject to anthropic impacts on land and water. It is estimated that at least 50% of these environments worldwide have been lost in the last hundred years. For São Paulo, the remnants of the várzea vegetation already occupied only 0.63% of the state territory in 2001. Tanquã is a floodplain in the Piracicaba river, whose natural flood pulse was reversed in relation to the region rainfall by the construction of a dam downstream. Ninety-four species of waterbirds occur in the area, 16 of which migrate, eight are threatened in the state of São Paulo, four are almost threatened and two do not have sufficient data in the literature to conclude their degree of threat. The further construction of several infrastructures designed to regulate water flow is foreseen in this river basin and the correct management of impacted areas such as Tanquã play an important role in the conservation of birds. We evaluated the temporal variation of the composition and abundance of the waterfowl community according to the water level of Tanquã. Monthly censuses were carried out during one year at seven counting points, in order to understand how artificially flooded areas could sustain different groups and prevent future biodiversity losses. We discuss the importance of the area as a habitat for resting and reproduction of migratory and threatened bird species in the state of São Paulo and the risk that this area may face in case its water regime is altered again. The project "Aproveitamento Múltiplo Santa Maria da Serra" is expected to cause the rise and stabilization of the water level at 6 or 10 meters from the current maximum, in order to extend the Tietê-Paraná Waterway in 50 kilometres. Different functional groups of waterfowl respond differently to the fluctuations on the river level, however, as overall bird abundance is negatively correlated with it, this additional modification in the flood pulse can cause the area to lose its ability to sustain such a high biodiversity. Future dam construction projects should take actions such as creating habitat heterogeneity and maintaining an adequate flood pulse in order to transform or maintain their areas of influence as important habitats for the globally threatened waterfowl community, thus contributing to their conservation.
Wetlands are globally recognized as priorities for biodiversity conservation and are among the planet's most fragile and threatened ecosystems, as they are subject to anthropic impacts on land and water. It is estimated that at least 50% of these environments worldwide have been lost in the last hundred years. For São Paulo, the remnants of the várzea vegetation already occupied only 0.63% of the state territory in 2001. Tanquã is a floodplain in the Piracicaba river, whose natural flood pulse was reversed in relation to the region rainfall by the construction of a dam downstream. Ninety-four species of waterbirds occur in the area, 16 of which migrate, eight are threatened in the state of São Paulo, four are almost threatened and two do not have sufficient data in the literature to conclude their degree of threat. The further construction of several infrastructures designed to regulate water flow is foreseen in this river basin and the correct management of impacted areas such as Tanquã play an important role in the conservation of birds. We evaluated the temporal variation of the composition and abundance of the waterfowl community according to the water level of Tanquã. Monthly censuses were carried out during one year at seven counting points, in order to understand how artificially flooded areas could sustain different groups and prevent future biodiversity losses. We discuss the importance of the area as a habitat for resting and reproduction of migratory and threatened bird species in the state of São Paulo and the risk that this area may face in case its water regime is altered again. The project "Aproveitamento Múltiplo Santa Maria da Serra" is expected to cause the rise and stabilization of the water level at 6 or 10 meters from the current maximum, in order to extend the Tietê-Paraná Waterway in 50 kilometres. Different functional groups of waterfowl respond differently to the fluctuations on the river level, however, as overall bird abundance is negatively correlated with it, this additional modification in the flood pulse can cause the area to lose its ability to sustain such a high biodiversity. Future dam construction projects should take actions such as creating habitat heterogeneity and maintaining an adequate flood pulse in order to transform or maintain their areas of influence as important habitats for the globally threatened waterfowl community, thus contributing to their conservation.
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Palavras-chave
Áreas úmidas, Diversidade funcional, Sazonalidade, Tanquã, Aves, Wetlands, Functional diversity, Seasonality, Birds