1. Influence of soft rush (Juncus effusus) on phosphorus flux in grazed seasonal wetlands
- Author
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Tweel, Andrew W. and Bohlen, Patrick J.
- Subjects
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WATER quality management , *WATER pollution , *ANALYTICAL chemistry , *CHEMISTRY - Abstract
Abstract: Livestock significantly affect wetland soils and vegetation but their impacts on wetland nutrient dynamics are poorly understood. We set up a full factorial laboratory experiment to assess the effects of Juncus effusus, grazing exclusion, and flooding on P flux from intact cores collected from seasonal wetlands in cattle pastures in south Florida. We collected intact cores from Juncus tussocks and plant interspaces inside and outside 4-year grazing exclosures in five replicate wetlands. We incubated the cores for 50 days under continuous flooding or weekly 1-day flooding cycles and measured P concentrations in surface and pore water. Grazing exclosures had less Juncus (17%) and bare ground (2%) than adjacent grazed areas (Juncus, 48%; bare ground, 12%), but did not affect P fluxes. Initial fluxes of soluble reactive P (SRP) were much higher in cores with Juncus (242±153mgPm−2 day−1) than without Juncus (14±20mgPm−2 day−1). In weekly flooded cores P fluxes fell to 19.7±13.4mgPm−2 day−1 in cores with and 2.7±2.6 in cores without Juncus. The strong effect of Juncus on P flux was an indirect effect of cattle grazing, but 4 years of grazing exclusion did not have a significant effect on P fluxes. [Copyright &y& Elsevier]
- Published
- 2008
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