Metro Regional Government
Date of Award
Master of Environmental Management (MEM)
Environmental Science and Management
1 online resource (ix, 90 pages)
Natural areas -- Oregon -- Portland Metropolitan Area, Wetland management -- Oregon -- Smith and Bybee Wetlands Natural Area, Introduced organisms -- Control, Reed canary grass -- Control
We sought to determine the effects of 13 years of hydrologic management on the wetland plant community in Smith and Bybee Wetlands Natural Area (SBW), an 809 ha palustrine wetland complex in north Portland, Oregon. Previous management efforts resulted in an altered hydrologic regime; historically high water levels in spring and low water levels in fall were replaced by persistent water levels with minimal annual variations. A water control structure was installed in 2003 to better approximate historic seasonal hydrologic changes to reduce invasive Phalaris arundinacea (reed canarygrass) cover and promote native wetland vegetation growth. Vegetation monitoring has been carried out in three phases since project initiation (2003-2004, 2008-2009, and 2015-2016) to assess restoration efforts. Using lineintercept and differential leveling methods, we measured 25 randomly established transects ranging from 21.5m to 280.7m (mean: 92.87m) during monitoring years for vegetation and elevation to determine changes in vegetation in relation to seasonally varying water levels. Overall, reed canarygrass percent cover has decreased from 46.5% in 2003 to 17.6% in 2016 (McNemar’s test; p
Lascheck, Robert P., "Long-Term Managed Flooding to Control Invasive Phalaris arundinacea L. and Help Restore Native Vegetation in an Urban Palustrine Wetlands Ecosystem" (2018). Master of Environmental Management Project Reports. 36.