First Advisor

Alan Yeakley

Community Partner

Metro Regional Government

Date of Award

3-2018

Document Type

Project

Degree Name

Master of Environmental Management (MEM)

Department

Environmental Science and Management

Physical Description

1 online resource (ix, 90 pages)

Subjects

Natural areas -- Oregon -- Portland Metropolitan Area, Wetland management -- Oregon -- Smith and Bybee Wetlands Natural Area, Introduced organisms -- Control, Reed canary grass -- Control

DOI

10.15760/mem.7

Abstract

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

Description

A report submitted in partial fulfillment of the requirements for the degree of Master of Environmental Management

Persistent Identifier

https://archives.pdx.edu/ds/psu/26260

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