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| Effects of Livestock Exclusion in Northeast Oregon |
Multiple counties in the Northeast, Oregon |
Primary Project Type: Riparian Restoration
Secondary Type: |
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Few studies have quantified the vegetation differences between stream reaches wh... |
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Primary Problem: Overgrazing
Secondary Problem: |
| Main Restoration Action(s): Grazing management |
| Native Fish Focus: N/A |
Is this project part of a watershed scale restoration? No
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| Project Dates: July 2002 to September 2002 |
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Initial Monitoring:
Restoration Implementation:
Follow-up Monitoring: |
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Lead Agency:
Department of Fisheries and Wildlife, Oregon State University
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| Project Location:
To examine how vegetation, geomorphic structure, and fisheries populations differed between grazed and ungrazed stream reaches, a total of 11 northeast Oregon streams were selected for study in 2000.
Click here for a map of the project area.
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Project Description:
The following information was taken and/or modified from Kaufman, J., Patricia McDowell, Peter Bayley, Hiram Li,and Robert Beschta, "Research/Evaluate Restoration of NE Oregon Streams," Project No. 2000-05100, 93 electronic pages, (BPA Report DOE/BP-00006210-1). To view this report in its entirety, click here.
Riparian vegetation is critical to the creek ecosystem. Plant roots provide stability to creek banks. The vegetation filters sediment and other contaminants from runoff (Skinner et al. 2000). Overhanging vegetation provides cover for fish and shade for stream temperature control. Logs from the riparian area can also be a source of instream fish habitat. Livestock grazing is the most widespread land use in the western United States and has been suggested to be a significant influence affecting riparian ecosystem structure, diversity, and function (Kauffman and Krueger 1983, Elmore and Kauffman 1991). Overgrazing in riparian areas can lead to a loss of bank stabilizing plants, formation of an over-widened channel, and increased sedimentation (Skinner et al. 2000).
Kauffman et al. (1996) suggested the first logical step in riparian restoration is the implementation of “passive restoration,” defined as the cessation of those activities that are causing ecosystem degradation or preventing recovery. Because the vegetation of riparian zones is adapted to frequent fluvial disturbances (Gregory et al. 1991, many riparian species possess adaptations facilitating a rapid recovery following both natural and anthropogenic disturbances. Therefore, cessation of livestock grazing along salmonid-bearing streams has been a common approach to fish and wildlife habitat restoration in the Interior Columbia Basin of Oregon and Washington.
Few studies have quantified the vegetation differences between stream reaches, which have been grazed and stream reaches, which are within exclosures in a wide diversity of stream types in the Pacific Northwest. This research was intended to provide an improved understanding of both the effects and effectiveness of exclosure of domestic livestock from the riparian area of streams in northeast Oregon. |
| Project Goals: The first objective of this research was to quantify the geomorphic, hydrologic, fisheries, and riparian vegetation responses to the passive restoration approach of livestock exclusion/corridor fencing along a variety of differing riparian/stream ecosystems in Northeastern Oregon. Based upon the research findings, the second objective was to develop management recommendations and delineate additional research needs to determine which type of approaches will yield the highest probability of enhancement of salmonid habitats. |
| Project Methods:
To examine how vegetation, geomorphic structure, and fisheries populations differed between grazed and ungrazed stream reaches, a total of 11 northeast Oregon streams were selected for study in 2000. Each study stream consisted of two reaches—a grazed reach and an ungrazed reach. Reach length for each site ranged from 99 to 340 meters. Grazed reaches were those in which livestock grazing (principally cattle) was a dominant use in the riparian zone and surrounding uplands. Ungrazed reaches were those where livestock grazing had been eliminated through the construction of riparian exclosures or corridor fences. Ages of the exclosures ranged from approximately 3 to 37 years. Grazing treatment ranged from light grazing every one out of three years to heavy season-long grazing. The goal was not to examine specific grazing strategies, but rather to determine whether differing vegetation patterns could be detected between riparian areas with and without livestock influences.
Click here for more information on methods used.
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The objective of this research was to study the effects of the passive restorati... |
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Grazed stream reaches, where livestock grazing was a dominant influence in the r... |
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| Monitoring Data and Collection
Methods: Monitoring was conducted on the paired study reaches to compare differences in riparian vegetation community composition, temperature, channel geomorphology, and salmonid population response to grazing or livestock exclusion.
For more information on monitoring methods and results, click here.
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Was this project effective
and how was this determined? Changes in vegetation composition structure as well as geomorphic features suggest that livestock exclusion succeeds in restoring many important components of productive wildlife and fish habitats. A significant increase in young-of-the-year salmonid density was evident across exclosures, but a difference was not detectable for larger fish whose home ranges greatly exceeded exclosure lengths of this study. Response of vegetation and geomorphology was greatest in the oldest exclosures, suggesting the quality of fish and wildlife habitats increase with increasing exclosure age. Land management agencies and landowners should be encouraged to maintain exclosures as long-term investments in habitat restoration. Small exclosures that cover only a few hundred meters of channel length may result in locally improved vegetation cover, channel geomorphology, and young-of-the-year salmonids, but improvements in the density of adult fish populations or water temperature were not detected. Effective restoration of water quality and fish populations would require exclosures to be significantly longer than most of the exclosures currently in place in the study area and monitoring would be necessary to understand the true impact of exclosures on water quality and total fish populations.
Based on results of this study, the scale of the exclosures sampled in this study (in terms of size and time) was too small to produce anticipated improvements in juvenile and adult coldwater fish populations. Larger areas of livestock exclusion for long time periods would be necessary for salmonid restoration. It is suggested that more effective and efficient restoration can be accomplished by a strategic approach at the sub-basin scale—taking into account the lengths of, and distances between, exclosures, and their locations with respect to the migratory patterns of salmonids in each sub-basin.
Many key questions about how and where to do restoration projects remain unanswered. Despite their strenuous efforts in site selection, the ex-post-facto research design of this study limited the strength of the research results. Monitoring of effectiveness of restoration projects must be improved. Preconstruction monitoring and ten to twenty years of post-construction monitoring should be initiated in a large number of new restoration projects. Monitoring should focus on ecosystem, habitat, and fish population changes within the watershed of concern. Further monitoring and research will lead to better decisions about location, scale, and methods of restoration projects.
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| Confounding Effects/Additional
Information: Additional analysis was completed on data collected from the grazed and ungrazed streams, including a generalized linear model using binomial distribution to account for additional variance. The findings of this analysis will be published in a future journal of North American Journal of Fish Management. |
| Project
Specs (all specs are estimates): |
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| For more information on this project
contact: |
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Hiram Li, Oregon State University, Email: hiram.li@oregonstate.edu
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| This information
was collected by: Kristin Keith |
| Project last updated on: 10/10/2006 |
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