ROADSIDE REVEGETATION

An Integrated Approach to Establishing Native Plants and Pollinator Habitat

3.7 Defining the Desired Future Condition

Once revegetation units and corresponding reference sites have been described, the DFC targets can be defined for each unit. The DFC target is the translation of the revegetation objectives into measurable goals for each revegetation unit. Specifically, the DFC target defines the desired or expected composition of vegetation at a particular point in time after the completion of the revegetation work.

An example DFC target would be, "one year after seeding, vegetative ground cover will be 40 percent and of this cover, 50 percent will be composed of native forb species beneficial to pollinators." Stating expectations in this manner will (1) clarify how the site will appear after treatments, (2) narrow down the appropriate revegetation treatments to meet the DFC target, and (3) define measurable criteria, or thresholds, for monitoring the success of a project.

Commonly stated DFC criteria include the following:

  • Vegetative ground cover
  • Bare soil cover
  • Native grass cover
  • Number of species of native grasses
  • Native forb cover
  • Number of species of native forb species
  • Seedling survival
  • Seedling density (plants per area)
  • Tree growth (height per year)
  • Coarse pollinator diversity
  • Pollinator abundance

Stating the DFC in measurable terms and with a time frame ensures that the project team, regulatory agencies, and the public have similar expectations of how the project will appear in the years following its completion. Quantifying the objectives also focuses the monitoring plan to collect only the information necessary to determine if project objectives were met. For example, if one of the objectives is erosion control, a DFC target might be, "the amount of bare soil one year after road construction will be less than 20 percent." Monitoring procedures would focus on measuring bare soil after one year. If another objective is to increase pollinator species, then a measurable threshold for success might be, "an increase of 50 percent pollinator abundance over reference site populations three years after seeding." Monitoring, in this case, would measure general pollinator types in reference sites and revegetation unit three years after completion of the project.

Another benefit in defining DFC targets is that it often will generate a discussion of whether they are achievable without investing in soil improvement or additional plant establishment methods. Unless DFC targets are stated and discussed, individual team members will develop their own concept of what success looks like. For example, a road project was being proposed next to a river with high fisheries values. The Storm Water Pollution Prevention Plan that had been prepared for the project stated that the cut slopes would have 100 percent ground cover, which would result in very low sediment delivery to the stream after construction. Team members discussed this DFC target and concluded that it was unachievable because of the lack of topsoil and shallow soils. This left the team the choice of either modifying the DFC target or improving the soil quality.

When developing DFC targets, it is important to consider the plant community succession that is likely to occur on each revegetation unit. In some cases, planting early seral species at the outset may work. By year 3, when the early seral species begin to decline, the late seral species may be increasing. In other cases, it may be necessary to intervene immediately after seeding or planting in order to meet the revegetation objectives of the project. For example, short-term revegetation planning might call for seeding grasses and forbs to stabilize the site. One year later, the site might be revisited to remove any invasive species before they produce seeds. Two years later, the site might be revisited to interplant conifers and shrubs. These three intervention points (seeding, weeding, and planting trees) speed succession in the desired direction.