title: Negative effects of excessive soil phosphorus on floristic quality in Ohio wetlands.
abstract: Excessive soil nutrients, often from agricultural runoff, have been shown to negatively impact some aspects of wetland plant communities. We measured plant-available phosphorus (Mehlich-3: MeP) in soil samples, and assessed the vascular plant community and habitat degradation at 27 emergent and 13 forested wetlands in Ohio, USA. We tested two hypotheses: (1) that an index of vegetation biological integrity based on floristic quality was lower in wetlands with higher concentrations of MeP in the soil, and (2) that higher concentrations of MeP occurred in wetlands with more habitat degradation (i.e., lower quality), as estimated by a rapid assessment method. Hypothesis (1) was supported for emergent, but not for forested wetlands. Hypothesis (2) was marginally supported (P=0.09) for emergent, but not supported for forested wetlands. The results indicate that the effect of concentration of phosphorus in wetland soils and the quality of plant species assemblages in wetlands is more complex than shown in site-specific studies and may depend in part on degree of disturbance in the surrounding watershed and dominant wetland vegetation type. Woody plants in forested wetlands are typically longer lived than herbaceous species in the understory and emergent wetlands, and may persist despite high inputs of phosphorus. Further, the forested wetlands were typically surrounded by a wide band of forest vegetation, which may provide a barrier against sedimentation and the associated phosphorus inputs to the wetland interior. Our results indicate that inferences about soil nutrient conditions made from rapid assessment methods for assessing wetland habitat condition may not be reliable.
authors.affiliation: U.S. Geological Survey, Great Lakes Science Center, Lake Erie Biological Station, 6100 Columbus Avenue, Sandusky, OH 44870, USA. Electronic address: mstapanian@usgs.gov.
authors.forename: Martin A
authors.initials: MA
authors.lastname: Stapanian
authors.affiliation: Ohio Environmental Protection Agency, 4675 Homer Ohio Lane, Groveport, OH 43125, USA.
authors.forename: William
authors.initials: W
authors.lastname: Schumacher
authors.affiliation: Ohio Environmental Protection Agency, 4675 Homer Ohio Lane, Groveport, OH 43125, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Gara
authors.affiliation: U.S. Department of Agriculture, Natural Resource Conservation Service, 100 Centennial Mall North, Lincoln, NE, 66508 USA.
authors.forename: Steven E
authors.initials: SE
authors.lastname: Monteith
mesh_terms: D000383:Agriculture; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D009820:Ohio; D010758:Phosphorus / Q000032:analysis*; D010944:Plants; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D053833:Wetlands
chemical_list: D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus
keywords: Mehlich-3 phosphorus; Rapid assessment method; Soil; Vegetation index of biological integrity; Wetland