Research Organization: Hopland Research & Extension Center,
Division of Agriculture & Natural Resources, University of
Principal Investigator: Dr. Robert M. Timm, Center Superintendent
Cooperating Researchers: Dr. Vic Claassen, Land Air & Water Resources, UC Davis
Charles E. Vaughn, Staff Research Associate IV, HREC
Research Assistants: Stephen L. Young, Staff Research Associate
___tba____, Postgraduate Researcher(s) (specialty in plant sciences)
Time Period of Project: June 1, 2002 through March 31, 2006
[Fiscal Years 2001-2002 through 2005-2006 (overlaps 5 fiscal years)]
Funding Requested: $410,087 450,507 (over 5 fiscal years)
The California Department of Transportation (Caltrans) manages approximately 15,000 miles of highway and more than 230,000 acres of right-of-way throughout the state. A major portion of the management and maintenance effort is associated with vegetation control. This need is driven by safety concerns, such as ensuring visibility of traffic and highway structures and minimizing fire potential by reducing vegetative biomass. Additionally, vegetation control provides benefits by reducing the presence of noxious weeds and other pests, and it is a major component of erosion control. The proper vegetation cover in Caltrans rights-of-way will improve motorist safety and erosion control, while reducing the need for mowing and/or herbicide use.
Caltrans District 1 includes a wide range of climates and plant communities found in Del Norte, Humboldt, Lake, and Mendocino Counties. With the completion of an Environmental Impact Report (EIR) in late 1992, a shift in focus from relying solely on chemical vegetation control to establishing native grasses and low-growing non-native fescues has begun to take shape. As part of an integrated roadside vegetation management (IRVM) program, Caltrans has completed revegetation seeding projects on numerous construction sites. The results from these projects have not been monitored extensively to determine whether they were either successes or failures. In addition, the revegetation practices, which resulted in successful establishment, have not been determined for the range of growing conditions within the four-county district.
The goal of this project is to improve the methodology for
successfully establishing native or desirable, low-maintenance
vegetation on sites/soils following road construction or where
elimination of undesirable vegetation has occurred.
Enumerate factors that are known to contribute to successful establishment of desirable vegetation (as defined by Caltrans landscape architects) on disturbed sites/soils.
Conduct literature review of this topic for publications, guidelines, and bibliographies pertinent to North Coastal California (Caltrans District 1).
Confer with revegetation, conservation biology, and plant ecology authorities with experience pertinent to North Coastal California conditions (e.g., faculty or extension staff within UC, State Universities, private universities and colleges, state and federal agencies, private firms)
Conduct site visits to locations of recent Caltrans revegetation attempts. Analyze such sites through a cursory review in which planting success is assessed by examining project specifications for seed species and planting methodology. Utilize standardized plant monitoring protocols for describing plant composition and cover. Additionally, take soil samples from selected Caltrans revegetation sites and nearby reference sites (less disturbed soils with established vegetation) to compare nutrient and organic contents, water holding capacity and microbial activity, which may include mycorrhizae.
Re-visit sites at least annually for duration of project to determine whether/what type of subsequent plant succession or invasive competition occurs. Attempt to conclude whether obvious variables provide predictive information.
From sites where vegetation establishment was unsuccessful, determine the circumstances or variables that appear to lead to unpredictable results or predictable planting failure. For such locations/circumstances, hypothesize changed planting and/or management strategies that would likely lead to successful revegetation. Pilot-test such treatments at appropriate sites.
Analyze field data from sites of revegetation attempts (see Objective I) using multivariate analyses in order to determine primary and secondary reasons why efforts failed or succeeded.
For sites where primary and secondary causes of revegetation failure appear most evident, develop strategies for initiating successful revegetation, coupled with testable hypotheses related to correcting causes of revegetation failure.
Pilot-test treatments or combinations of treatments at three to five selected sites with moderate soil conditions, in order to refine a wide range of establishment techniques in controlled settings1 (HREC, state parks, private landowners, etc.) where more replications and significant differences can be determined. Treatments may include: seeding density, species composition (based on appropriate species for the area), timing of seeding, maintenance for establishment and weed control, and plant growth regulators. Amendments may be applied to bring soils to modest nutrient and water holding capacity levels, if needed.
Evaluate success of test treatments at field sites for overall improved public safety along highways in terms of establishment success (maintained plant diversity, while decreasing noxious, invasive species), erosion prevention or control, and fire risk reduction2 through the available time period of this project.
1 Settings include lab, greenhouse, and field situations.
2 Specific measurements useful in such evaluation may include percent cover, plant species composition, plant survival through time (plant growth habit - annual, perennial, biennial), standard erosion descriptions and measures, cost:benefit, water quality measures for runoff such as suspended solids or nutrients.
Through practical application of information gained in meeting Objectives I and II, formulate improved strategies/specifications for revegetation projects on difficult sites, so as to increase the chances of successful establishment of desirable vegetation that will successfully compete with other less desirable plant species in the local environment. Strategies are likely to be specific to several common problem site situations (e.g., hot sites, modest soil conditions, right-of-way slopes, and previous dense infestations of undesirable plants). Report on findings and developing strategies to Caltrans personnel through seminars or workshops to be held in both Northern and Southern California. Share research findings through appropriate scientific (peer-reviewed) as well as semi-technical publications in appropriate periodicals. Provide findings to Caltrans in appropriate format for inclusion in agencyís web sites.
In consultation with colleagues and cooperators, draft guidelines for improving success of revegetation projects on various types of North Coast sites where past success of such efforts has been low. (These guidelines are likely to be specific to the more common site characteristics).
Establish a demonstration project site approximately 2 acres in size to show a vegetative conversion of an area dominated by weeds or other undesirable plant species.
Provide wording to Caltrans, facilitating the agencyís incorporation of this new information and improved revegetation strategies into the District 1 erosion control specifications for construction projects.
Publish findings by submitting research to appropriate journals and periodicals
Provide finds to Caltrans in HTML format or other format appropriate for inclusion in web sites.
Determination and quantitative analysis of whether past seeding / planting projects have been successes or failures for Caltrans.
From this information, make necessary changes in current seeding / planting methods (i.e. timing, maintenance) to make future construction revegetation projects more successful and cost effective
Overall reduction in right-of-way maintenance costs (i.e. mowing, mulching, and bioherbicides) once native/low-growing vegetation has been established and niches for invasive, non-native species have been severely diminished.
Increase biodiversity of environment for wildlife habitat and lower the spread of invasive species via highway corridors.
Improve public perception, at the risk of lowering aesthetically appealing ìlawn-scapedî settings.
The results of this research will provide Caltrans District 1 information about whether changes are needed in current protocols for revegetating sites after construction for erosion control and habitat biodiversity. Findings and recommendations will be shared with agency personnel through regional workshops or seminars, as well as through publications in various journals and semi-technical magazines. Personnel involved with revegetation projects will be better informed on the most effective procedures for establishing native vegetation. Moreover, a reduction in both the costs of Caltrans roadside maintenance and public concern will be realized.
Year 1 - June 2002 (FY2001-2002)
Search literature/internet for information related to establishing native vegetation.
Review current revegetation practices used by Caltrans including site preparation and seeding procedures.
Begin locating appropriate rights-of-way and roadside sites for planting trials.
Year 2 - July 2002 through June 2003 (FY2002-2003)
Inventory and evaluate selected revegetation sites (i.e. species frequency, canopy cover, species height, and aboveground biomass)
Provide description of apparent erosion that has occurred at each site sampled.
Perform detailed soil analysis including nutrient content, organic matter, water holding capacity and microbial populations on sites and nearby reference sites with established vegetation.
Continue literature/internet search and maintain/establish contacts with persons having particular expertise concerning revegetation techniques/practices.
Interim report that summarize findings, conclusions, and recommendations for Objective I.
Establish plantings and begin testing treatments in controlled settings (lab, greenhouse, field plots)
Construct 3 field plots using improved site preparation and vegetation establishment techniques
Year 3 - July 2003 through June 2004 (FY2003-2004)
Monitor existing plantings in controlled settings with more plots added if needed.
Revegetation strategies and specific development for plant establishment will be ready for pilot-testing by means of incorporation into construction projects.
Workshops/seminars for Caltrans personnel will be initiated.
Installation of vegetation conversion demonstration project at selected location(s).
Year 4 - July 2004 through June 2005 (FY2004-2005)
Perform necessary maintenance on sites during the growing season.
Evaluate sites from previous years and prepare appropriate reports.
Revise revegetation strategies, based on recent results and hypotheses.
Interim report that summarize findings, conclusions, and recommendations for Objective II.
Continue to report results of work in written, oral, and web-based formats as appropriate.
Submit manuscripts to appropriate journals, periodicals, and conferences or symposia.
Provide written suggestions / recommendations to agency, based on results to date.
Year 5 - July 2005 through March 2006 (FY2005-2006)
Evaluate sites from previous years, and summarize data.
Continue to report results of work in written, oral, and web-based formats as appropriate. Work with journal editors on revision of manuscripts, or on final details of accepted papers, for publication. Attend appropriate conferences and symposia to report on findings.
Provide appropriate forums for agency to receive and disseminate information within the state.
Prepare, review, and finalize project final report, which will include suggestions to agency on follow-up or related studies that would build on information gained in this project.
Robert M. Timm, Ph.D. (Superintendent, UC Hopland Res. & Ext. Center) will provide overall coordination and project management. Stephen L. Young, Staff Research Associate II at the Hopland R&E Center (currently employed under existing Study I funded by Caltrans) will devote a portion of his time to the new project in its first 12 months, and then will become full-time on this project beginning in July 2002. Two additional Postgraduate Researchers (or Staff Research Associate I) with expertise in plant sciences will be filled; depending on interests and qualifications of applicants, this position could be combined into a single full-time position. Our anticipation is that this function would be performed by 1 or 2 graduate students who would be undertaking M.S. thesis projects at UC Davis or UC Berkeley. Vic Claassen, Ph.D. (Dept. of Land Air & Water Resources, UCD) will assist in site selection, field sampling implementation, and data interpretation with particular emphasis on soil sampling. Charles Vaughn, SRA IV at HREC (M.S. in soil sciences) will serve as a consultant and resource person to the project and will conduct selected lab analyses. The individuals funded by this project will be responsible for field work, including study plot establishment, monitoring, and data collection and analysis; and for preparing manuscripts and articles, web-based information, and oral reports to Caltrans personnel and for submission to appropriate professional meetings and symposia. Dr. Timm will provide appropriate oversight for the team and the project during its duration.
Laboratory, office, and dormitory facilities are available at the UC Hopland Res. & Ext. Center (HREC) for project personnel. Equipment necessary to establish field plots at HREC (tractors, roto-tillers, seeders, plot fence construction tools), and to measure plant growth and frequency of occurrence are also available from the University. University vehicles suitable for highway use, for travel to study sites, are available at HREC for use by project staff. Other items provided by the University which are not charged to the project grant include computers for data input, storage, and analysis, and for preparing subsequently publications and audio-visual materials for presentation to various audiences.
Quarterly progress reports will be submitted as required by Caltrans. Interim reports generated in Years 2 and 4 will be incorporated into a comprehensive, detailed final report to be submitted to Caltrans upon the projectís completion. The final report will include a 1-2 page Executive Summary as well as a summary of relevant project data in laymenís terms.
R.M. Timm and S.L Young
UC Hopland Res. & Ext. Center
January 25, 2002 revision
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Updated December 20, 2022 - Go to The Reveg Edge website