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Date Permissions Signed


Date of Award

Spring 2020

Document Type

Masters Thesis

Department or Program Affiliation

Huxley College of Environmental Sciences

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

Bauman, Jenise

Second Advisor

Matthews, Robin A., 1952-

Third Advisor

Helfield, James M.

Fourth Advisor

Chenoweth, Joshua


This thesis investigated the managed revegetation outcomes of the exposed Lake Mills reservoir bed was investigated following the Glines Canyon dam removal on the Elwha River located in the Pacific Northwest, United States. During the following four years of restoration, one seeded species, riverbank lupine (Lupinus rivularis), quickly established on the coarse textured terraces that also had low organic matter (OM) and low soil nitrogen (N) levels. Nitrogen-fixing lupines may facilitate plant recruitment and conifer establishment, while demonstrating a relationship with ectomycorrhizal (ECM) communities which perform essential forest ecosystem functions. The purpose of this study was to investigate lupine’s influence on forest recovery, measured under three levels of abundance: sparse, medium, and dense. Each plot was assessed for nitrogen bioavailability, tree growth, plant community structure, soil N and OM development, and ECM abundance. My study demonstrates that lupine abundance has a positive relationship with restoration conifer growth and foliar N concentrations. In addition, lupine abundance corresponds with the surrounding plant species richness and diversity. Finally, lupine abundance has an inverse relationship with conifer root ECM colonization, thereby demonstrating that certain ecological conditions driven by the presence of lupine may dictate the symbiotic strategies between trees and fungi. Though the data illustrate lupine’s ability to influence N uptake in neighboring conifers, I did not see differences in soil N or differences in soil OM during this early phase of succession. I provide supportive evidence of lupine’s ability to aid in forest restoration in highly disturbed novel landscapes following dam removal is demonstrated. These data will be synthesized into best management practices for similar revegetation projects where dam removal, coupled with seeding and planting, restores forests that are linked to the greater riverine ecosystems.




lupine, forest restoration, Elwha River, Lake Mills, ectomycorrhizae


Western Washington University

OCLC Number


Subject – LCSH

Dam retirement--Washington (State)--Upper Elwha Dam; Riverbank lupine--Washington (State)--Elwha River; Grassland restoration--Washington (State)--Elwha River; Forest restoration--Washington (State)--Elwha River; Ectomycorrhizas

Geographic Coverage

Upper Elwha Dam (Wash.); Elwha River (Wash.)




masters theses




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