Start Date

2-3-2021 10:20 AM

End Date

2-3-2021 11:25 AM

Abstract

Fen-wetland ecosystems are rare nationwide. Their unique groundwater regime and chemistry, along with a floating, vegetated peat mat that may occur, support diverse and rare plant and wildlife communities. A fen’s ecological benefits are considered even greater within an urbanized setting through its natural attenuation of runoff and pollutants, though these ecosystem services may diminish should the urban-sourced impacts eventually alter the fen’s bio-physical condition. Here we will present how determining a fen’s key bio-physical factors and understanding their combined sensitivity to external processes is necessary to define and address potential threats to a fen’s conservation.

Located within a 100-acre Metro-owned natural area along the lower Willamette River, the last known remaining fen composed of a groundwater-fed lake with a densely vegetated floating peat mat in the region is vulnerable to threats that could alter its fragile biochemistry. Threats include stormwater runoff, groundwater reductions from local pumping, nutrient input from septic tanks, and invasive species. To inform conservation measures, Metro’s goal was to assess the fen’s watershed inputs and bio-physical condition by studying the site hydrology, water and soil quality, and vegetation. Initial results reveal a unique ecosystem with counter groundwater and surface-water flow directions due to the unique geologic setting, eutrophic lake conditions from high nutrient loading and concentration, acidic water chemistry and soils from parent bedrock materials, and a diverse plant community consisting of 27 taxa of rare plants. Ongoing monitoring of the fen is helping to assess its condition, help detect future trends, and inform preservation of this unique habitat and potential recommendations for restoring disturbed fens elsewhere in the region.

Subjects

Habitat assessment, Hydrology, Land/watershed management, Plant ecology, Water quality

Persistent Identifier

https://archives.pdx.edu/ds/psu/35474

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Mar 2nd, 10:20 AM Mar 2nd, 11:25 AM

Understanding the bio-physical characteristics of a fen ecosystem to inform management and conserve the rare habitat

Fen-wetland ecosystems are rare nationwide. Their unique groundwater regime and chemistry, along with a floating, vegetated peat mat that may occur, support diverse and rare plant and wildlife communities. A fen’s ecological benefits are considered even greater within an urbanized setting through its natural attenuation of runoff and pollutants, though these ecosystem services may diminish should the urban-sourced impacts eventually alter the fen’s bio-physical condition. Here we will present how determining a fen’s key bio-physical factors and understanding their combined sensitivity to external processes is necessary to define and address potential threats to a fen’s conservation.

Located within a 100-acre Metro-owned natural area along the lower Willamette River, the last known remaining fen composed of a groundwater-fed lake with a densely vegetated floating peat mat in the region is vulnerable to threats that could alter its fragile biochemistry. Threats include stormwater runoff, groundwater reductions from local pumping, nutrient input from septic tanks, and invasive species. To inform conservation measures, Metro’s goal was to assess the fen’s watershed inputs and bio-physical condition by studying the site hydrology, water and soil quality, and vegetation. Initial results reveal a unique ecosystem with counter groundwater and surface-water flow directions due to the unique geologic setting, eutrophic lake conditions from high nutrient loading and concentration, acidic water chemistry and soils from parent bedrock materials, and a diverse plant community consisting of 27 taxa of rare plants. Ongoing monitoring of the fen is helping to assess its condition, help detect future trends, and inform preservation of this unique habitat and potential recommendations for restoring disturbed fens elsewhere in the region.