Roadside Revegetation

PLANNING PHASE ONE: ORIENT
adding fill, and applying salvaged topsoil. Since the area is a pollinator habitat emphasis area,
the seed mix will have more than 50 percent pollinator forb species. Flowering shrubs and trees
will be planted in clumps. Salvaged logs from the road clearing operation will be randomly
placed upright and on the ground for pollinator nesting habitat. Unit II includes fill slopes that
will be amended with shredded wood to increase infiltration rates and capture and filtrate
road surface runoff water. A low-growing native grass and forb seed mix will be applied. Unit
III includes steep-cut slopes with high erosion potential that will be terraced and a seed mix
primarily composed of grasses for erosion control will be applied in a bonded fiber matrix
(BFM). Unit IV is a shallow draw where all road ditch water collects. It will be constructed as a
bioretention swale to retain and filter sediments and road pollutants from the water before
entering the stream. Wetland seedlings will be planted.
Figure 4-9 was based on soil types, road components, and revegetation objectives. Each unit
has a desired future condition and types of treatment that will be employed.
4.5 LOCATE REFERENCE SITES
Reference sites provide a natural model for possible vegetation outcomes and are important
for defining DFCs, as well as evaluating and monitoring the project following implementation
(SER 2004). They can also be used to document the types and amounts of pollinator species
that may be present in putatively natural environments near the project area.
Each revegetation unit should have at least one corresponding reference site that models the
expected outcome or DFC of the unit. Ideally the reference site shows how a revegetation unit
might recover from disturbances at different points in time after road construction. Reference
sites can be considered a snapshot, or series of snapshots, of possible future outcomes. They
demonstrate a point in time along a desirable developmental trajectory for a plant community.
Using reference sites to understand the possible vegetative outcomes after disturbances will
help the designer develop realistic expectations and provide a guide to the development of
appropriate revegetation strategies for each revegetation unit. The most important aspect
of reference sites is that they provide examples of plant communities from which designers
can chose individual species for use in the revegetation project. The designer may sometimes
choose to obtain baseline ecological data from several reference sites and then assemble
DFCs (SER 2004).
The two types of reference sites are disturbed and undisturbed. Disturbed reference sites are
areas, typically old road cuts and road fills, that have recovered, whereas undisturbed reference
sites are relatively pristine sites that lack major disturbances in the recent past. For most road
projects, disturbed reference sites are the most helpful because they represent sites that are
ecologically similar to the revegetation unit and have recovered from disturbances similar to
those planned. Undisturbed reference sites may also be used when ecological restoration is
an objective or when suitable disturbed reference sites are not available.
Disturbed reference sites can be categorized several ways:
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Type of disturbance
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Length of time after the disturbance
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Desirability of the recovered vegetation
Disturbed reference sites can be old road cuts and fills, abandoned roads, ground-based
logging sites, waste areas, rock source sites, ski runs, or other areas that have recovered from
major soil disturbances. Disturbed reference sites often show a range of possible vegetative
outcomes years after disturbance. Some sites will show good recovery and include stable soil,
be visually pleasing, and populated by functioning communities of native plants. Others might
show what can go wrong if revegetation is not carried out properly, including erosion, poor
ground cover, weed infestation, and a lack of native vegetation. Understanding the conditions
that lead to these vegetative outcomes can be a guide to avoiding them in the future.
Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat
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