Year of Award

2009

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Forestry

Department or School/College

College of Forestry and Conservation

Committee Chair

Cara Nelson

Commitee Members

Cory Cleveland, James Mital, John Maron

Keywords

and watershed restoration, native plant restoration, nonnative seed, road decommissioning, road removal, seed establishment, soil bulk density, water holding capacity

Publisher

University of Montana

Abstract

Road decommissioning is increasingly recognized as a critical first step in the restoration of terrestrial and aquatic habitats. In the past two years alone, the United States Congress has appropriated $90 million for road removal and watershed restoration. Despite this relatively large public investment, little is known about the efficacy or ecological effects of road-removal practices. One particularly important issue is the impact of post-road-removal revegetation strategies. This study evaluated 1) short-term effects of road decommissioning on plant community composition, 2) effects of seed-mix seed origin (native vs. nonnative), species diversity, and seeding density on vegetative establishment, and 3) impact of overstory canopy and coarse woody debris on revegetation success on recently decommissioned roads. Total vegetative cover declined by 60% one-year after decommissioning, with nonnative plants showing the greatest declines (ca. 90%). Although managers often justify the use of nonnative seed mixes by the need for rapid establishment of plants on disturbed sites, we did not find significant differences in percent cover of total vegetation between plots seeded with native versus nonnative species, one year after treatment. Furthermore, cover of native species was significantly higher on plots seeded with natives compared to other treatment plots (12.3% vs. 7.8%, respectively). On treatments seeded with nonnative species, 18% of total vegetative cover was due to cover of seeded species; in comparison, seeded species accounted for 43% of total vegetative cover on native treatments. These findings suggest that native seed mixes actually may outperform nonnative ones in terms of vegetative establishment after disturbance associated with road removal.

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© Copyright 2009 Ashley Stevenson Grant