Publicação
Eutrophication alters the effects of riparian plant diversity on litter decomposition by macroinvertebrates
| Resumo: | In low-order forested streams, plant-litter decomposition is a key ecosystem process. Invertebrate shredders are responsible for the breakdown of plant litter and are very sensitive to stream water quality degradation. Increased eutrophication and loss or alteration of riparian vegetation can have negative effects on stream organisms and alter ecosystem processes. However, the interactive effects of riparian vegetation loss and increased nutrient concentrations in the stream water are poorly understood. In this study, we investigated if plant-litter decomposition and invertebrate assemblages were affected by leaf litter diversity and if eutrophication modulated the observed effects. Leaves from five riparian tree species (Alnus glutinosa, Castanea sativa, Eucalyptus globulus, Platanus sp. and Quercus robur) were used either alone or in mixtures of equally partitioned mass of 2, 3 and 5 species, in a total of 12 combinations. Leaves were placed in coarsemesh bags and immersed in seven streams of Northwest Portugal along a gradient of eutrophication, for 38 days. Leaf litter diversity had positive effects on litter decomposition but negatively affected invertebrate assemblages. Eutrophication modulated leaf litter diversity effects by suppressing positive diversity effects on litter decomposition and by negatively affecting invertebrate assemblages. A possible homogenization of litter nutrient content in leaf mixtures might explain the negative litter diversity effects on invertebrate communities, by promoting invertebrate unselective feeding or increasing species competition. Moreover, harmful effects of toxicant compounds, such as ammonia, might have contributed to the negative diversity effects on invertebrate assemblages in eutrophic streams. These findings illustrate that human activities alter litter decomposition dynamics in streams and the associated biotic communities. |
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| Autores principais: | Fernandes, Eva Lima |
| Ano: | 2011 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | In low-order forested streams, plant-litter decomposition is a key ecosystem process. Invertebrate shredders are responsible for the breakdown of plant litter and are very sensitive to stream water quality degradation. Increased eutrophication and loss or alteration of riparian vegetation can have negative effects on stream organisms and alter ecosystem processes. However, the interactive effects of riparian vegetation loss and increased nutrient concentrations in the stream water are poorly understood. In this study, we investigated if plant-litter decomposition and invertebrate assemblages were affected by leaf litter diversity and if eutrophication modulated the observed effects. Leaves from five riparian tree species (Alnus glutinosa, Castanea sativa, Eucalyptus globulus, Platanus sp. and Quercus robur) were used either alone or in mixtures of equally partitioned mass of 2, 3 and 5 species, in a total of 12 combinations. Leaves were placed in coarsemesh bags and immersed in seven streams of Northwest Portugal along a gradient of eutrophication, for 38 days. Leaf litter diversity had positive effects on litter decomposition but negatively affected invertebrate assemblages. Eutrophication modulated leaf litter diversity effects by suppressing positive diversity effects on litter decomposition and by negatively affecting invertebrate assemblages. A possible homogenization of litter nutrient content in leaf mixtures might explain the negative litter diversity effects on invertebrate communities, by promoting invertebrate unselective feeding or increasing species competition. Moreover, harmful effects of toxicant compounds, such as ammonia, might have contributed to the negative diversity effects on invertebrate assemblages in eutrophic streams. These findings illustrate that human activities alter litter decomposition dynamics in streams and the associated biotic communities. |
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