Vegetation Restoration Concepts
Chapter 810 of the Roadside Manual
Chapter 810 of the Roadside Manual contains guidelines that provide the background for the development of effective vegetation restoration methodologies. Two basic restoration approaches are used: managed succession and accelerated climax community development. They are based on the principles of plant succession in natural ecosystems.
Map of Washington State Ecoregions
It is the policy of WSDOT to use native plants. This map is an aid in determining what is considered native, and may be used to help in specifying and obtaining plant materials.
Ecoregions denote areas within which ecosystems (the type, quality, and quantity of environmental conditions) are generally similar. The approach used to compile this map is based on the premise that ecological regions can be identified through the analysis of the patterns and the composition of biotic and abiotic phenomena that affect or reflect differences in ecosystem quality and integrity (Wiken 1986; Omernik 1987, 1995). These phenomena include geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another regardless of the hierarchical level. (http://www.epa.gov/wed/pages/ecoregions/level_iii.htm)
The map of Washington State Ecoregions is derived from Omernik, J.M. 1987. Ecoregions of the conterminous United States Map (scale 1:7,500,000). Annals of the Association of American Geographers 77(1):118-125.
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Vegetation Alteration
Neighbors and businesses adjacent to WSDOT right-of-way often request to alter, remove, or even plant trees, shrubs, and plants on WSDOT property. WSDOT works with others to plant on our property; however, WSDOT policies do not support requests for removal or alteration of vegetation. There may be rare exceptions that vegetation alteration may be allowed if it is mutually beneficial to the goals of the transportation facility. The following documents list the policies and procedures to evaluate these requests.
FHWA Memos
Standards of Success for Wetland Mitigation
The Wetland Mitigation Standards of Success Study is a project of the Roadside and Site Development Unit of the Washington State Department of Transportation (WSDOT). It is designed to identify scientifically-based benchmarks for establishing vegetation success standards on wetland compensatory mitigation projects. Until now there has been little research done on longer-term ecological development of mitigation sites, or on how natural wetlands recover from disturbances. As a result, there was no data available on which to base ecologically viable success standards. This resulted in project proponents having to use their "best professional judgment" in setting performance goals.
Phase One of this study was completed in October 1999. It included a literature review of plant succession in Pacific Northwest wetlands, identification of potential study sites, a pilot study, and a recommended work plan for Phase Two.
Phase Two of this study surveyed and documented structural characteristics of vegetation within forested and scrub-shrub zones of wetland mitigation sites 6-11 years old. Each site was freshwater, located within the Puget Trough of Washington, and contained established stands of woody vegetation. Quantitative data were recorded on cover and density of woody vegetation, as well as cover of reed canarygrass. Additional qualitative observations included hydrology indicators and hydrogeomorphic settings, soils, herbaceous vegetation, and surrounding land use. Through this data, benchmarks for performance standards were proposed for forested and scrub-shrub components of wetland mitigation projects.
The study was funded by the Environmental Protection Agency (EPA) and WSDOT.