Fourteen Challenges for Mitigation Planting Plans
I worked with and reviewed over eighty different stream restoration projects as the landscape architect for a state transportation department. Some of the common roadside stream restoration struggles were:
• Grading and clearing were designed contrary to successful plant establishment.
• Over-clearing took place within the stream buffers.
• In-the-field staking errors resulted when stream buffers were delineated in rectangles (because that is the way they were drawn on the plans).
• Utility easement were missed, and trees proposed under power lines.
• Inexperienced designers, unfamiliar with restoration pitfalls and department policy, were assigned to the environmental task orders.
• When engineers saw a problem, they responded with rip rap.
• Site visits were rare designing, so designers ended up clearing existing, buffer-holding tree roots.
• Many consultants were not aware of clear zone requirements and proposed trees within the vehicle recovery safety zone.
• Standard specifications only covered ornamental landscape planting, and restoration planting is much different.
• In-the-field monitoring and enforcement of the clearing, grading, planting, and maintenance were not done properly.
• Invasive plants were often in and adjacent to mitigation sites, but no chemical control, fertilizer, or lime were allowed within the buffer areas.
• Storm events sometimes caused blowouts and washed away plant material on new stream relocations.
• There were many different phases of a project—negotiations, task order creation, conceptual design, preliminary design, final design, installation, maintenance. Without efficient communication, problems might go unsolved for months or years.
• The landscape architects were only called in when the restoration team needed a plant suggestion. “What should we plant here?”
Mindset is everything. The big talk is green, non-structural infrastructure for construction sites, but the money is obviously in structural products. Old-school engineers tend to think plants are a simple afterthought– just seed with Lespedeza or Bermuda grass, right? They like plants that tenaciously grab a typical, steep, roadside 2:1 slope and resist designing flatter slopes for better plant establishment in the interest of saving right of way purchases.
The push to use pervious pavements should not be done rather than vegetative mitigation. Green infrastructure should include green plants. The focus is on calculations, charts, certification points, and meeting the technical letter of the law rather than restoring sites is a strong distraction from the goal of healing a disturbed site.
Break through the current mindset, but it is not easy. Explain that restoration planting of a multitrophic mix on a gentle slope is cost effective and the best way to meet environmental agency requirements. Using bare root seedlings and a riparian seed mix is not only the easiest way to establish a stable forested buffer, it is the least expensive. Seedlings cost less than $2 and riparian seeding runs about $ 1500/acre. It’s a great deal for everybody and the buffer.