Advisor

Alan Yeakley

Date of Award

1-1-2011

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Environmental Science and Management

Department

Environmental Science and Management

Physical Description

1 online resource (xi, 114 p.) : ill.

Subjects

Wetland management -- Lower Columbia River Watershed (Or. and Wash.), Reed canary grass -- Lower Columbia River Watershed (Or. and Wash.), Riparian restoration -- Lower Columbia River Watershed (Or. and Wash.), Riparian areas -- Lower Columbia River Watershed (Or. and Wash.) -- Management, Grazing -- Environmental aspects -- Lower Columbia River Watershed (Or. and Wash.)

DOI

10.15760/etd.284

Abstract

The purpose of this study was to examine the characteristics of riparian plant communities along a succession gradient of livestock exclusion in the Lower Columbia River Basin (LCRB). Livestock exclusion is an example of a passive restoration practice throughout the region. However, few studies have focused on the effects of livestock or livestock exclusion on riparian wetland ecosystems in this area. Two passive restoration sites, 3 and 13 years since livestock exclusion, and a control site with a continued livestock grazing presence were examined. It was hypothesized that native plant species richness would be lower in the excluded wetlands than in the grazed wetland due to the competitive exclusion from an increase in non-native plant dominance in the absence of grazing. Data were collected along six (45-60m) randomly distributed transects which were aligned perpendicular to the wetland shoreline of each site, providing a total of 18 transects with an accumulative length of approximately 990 meters. Vegetation cover data were collected for 10 cm intervals along these transects using the line intercept method during low water periods in August and September of 2009. The Kruskal-Wallis one-way nonparametric analysis of variance by ranks and the Mann-Whitney U test were used to detect significant (p

Persistent Identifier

http://archives.pdx.edu/ds/psu/7011

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