Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat

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Disclaimer for References to Greenhouse Gas in this document:

On January 20, 2025, President Trump signed Executive Order (E.O.) 14148 --Initial Rescissions of Harmful Executive Orders and Actions and E.O. 14154 – Unleashing American Energy. The E.O.s revoked E.O. 13990 – Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis (January 20, 2021) and E.O. 14008 – Tackling the Climate Crisis at Home and Abroad (January 27, 2021). Subsequently on January 29, 2025, Secretary Duffy signed a Memorandum for Secretarial Offices and Heads of Operating Administrations – Implementation of Executive Orders Addressing Energy, Climate Change, Diversity, and Gender. On February 25, 2025, the Council on Environmental Quality (CEQ) published an Interim Final Rule removing the CEQ’s National Environmental Policy Act (NEPA) implementing regulations, effective April 11, 2025 (90 Fed. Reg. 10610). As a result of these actions, FHWA will not include greenhouse gas emissions and climate change analyses in the federal environmental review process. Any purported greenhouse gas emissions and climate change impacts will not be considered in the federal decision.

Table of Contents

• Chapter 1: Introduction
  • Introduction
  • 1.1 An Integrated Approach
  • 1.2 The Ecological Context of Roads
    • 1.2.2 Present Awareness
    • 1.2.3 Trends in Road Construction
    • 1.2.4 Challenges and Opportunities
    • 1.2.5 Why Revegetate Roadsides with Native Plants?
  • 1.3 Objectives of this Report
  • 1.4 Scope
  • 1.5 Approach
    • 1.5.1 Sustainable Revegetation on Roadsides
    • 1.5.2 What is the "Roadside"?
    • 1.5.3 What are Native Plants?
    • 1.5.4 Why the Emphasis on Pollinators?
    • 1.5.5 Goal-Oriented, Context-Sensitive, and Integrated
  • 1.6 How to Navigate through this Report
• Chapter 2: Initiation
  • 2.1 Introduction
  • 2.2 Preliminary Tasks of Initiation
    • 2.2.1 Defining Cooperators Processes, Timelines, and Milestones
    • 2.2.2 Defining Objectives: What is the Project Trying to Accomplish?
  • 2.3 The Process of Road Development
    • 2.3.1 Road Planning and Programming
    • 2.3.2 Road Project Development
    • 2.3.3 Construction
    • 2.3.4 Maintenance
  • 2.4 Road Construction Plans
  • 2.5 Interpreting Engineering Views for Revegetation Planning
  • 2.6 Understanding Technical Concepts and Terminology
• Chapter 3: Planning
  • 3.1 Introduction
  • 3.2 Defining Revegetation Objectives
  • 3.3 Gathering Pre-field Information
    • 3.3.1 Climate Pre-Field Assessment
    • 3.3.2 Soils pre-field assessment
    • 3.3.3 Vegetation pre-field assessment
    • 3.3.4 Pollinators pre-field assessment
    • 3.3.5 Road Plans
  • 3.4 Defining Revegetation Units
  • 3.5 Identifying Reference Sites
  • 3.6 Gathering Field Information
    • 3.6.1 Vegetation field Assessment
    • 3.6.2 Soils field Assessment
    • 3.6.3 Pollinator Field Assessment
  • 3.7 Defining the Desired Future Condition
  • 3.8 Identifying Limiting Factors to Plant Establishment
    • 3.8.1 Water Input
    • 3.8.2 Available Water Storage and Accessibility
    • 3.8.3 Water Loss
    • 3.8.4 Nutrient Cycling
    • 3.8.5 Surface Stability
    • 3.8.6 Slope Stability
  • 3.9 Identify Factors That Affect Pollinators
    • 3.9.1 Nectar and Pollen Sources
    • 3.9.2 Breeding Habitat
    • 3.9.3 Nesting Habitat
    • 3.9.4 Water Sources
    • 3.9.5 Shelter and Overwintering
    • 3.9.6 Landscape Connectivity
    • 3.9.7 Road Mortality
    • 3.9.8 Vegetation Management
  • 3.10 Inventory of Site Resources
    • 3.10.1 Topsoil
    • 3.10.2 Duff and Litter
    • 3.10.3 Subsoil and Parent Material
    • 3.10.4 Woody Material
  • 3.11 Developing a Vegetation Management Strategy during Project Design
    • 3.11.1 Introduction
    • 3.11.2 Integrating Road Maintenance Objectives into the Revegetation Plan
    • 3.11.3 Protecting Healthy Plant Communities
    • 3.11.4 Creating a Weed-Resistant Roadside Environment
    • 3.11.5 Keeping Weed Sources from Entering the Project
    • 3.11.6 Controlling Unwanted Vegetation
    • 3.11.7 Designing for Safety and Utility Protection
    • 3.11.8 Designing to Isolate Wildlife from Vehicles
    • 3.11.9 Designing for Disturbances
    • 3.11.10 Designing for Carbon Sequestration
  • 3.12 Select Site Improvement Treatments
  • 3.13 Selecting Plant Species for Propagation
    • 3.13.1 Developing a Potential Plant Species List
    • 3.13.2 Ensure Local Adaptation and Maintain Genetic Diversity
  • 3.14 Select Plant Establishment Methods
    • 3.14.1 Selecting Plant Materials
    • 3.14.2 Determine Outplanting Windows
  • 3.15 Develop a Revegetation Plan
• Chapter 4: Revegation Plan Example
• Chapter 5: Implementation
  • 5.1 Introduction
    • 5.1.1 Developing Contracts
    • 5.1.2 Maintaining Schedules and Materials Inventory
    • 5.1.3 Coordinating with Construction Engineer
    • 5.1.4 Implementation Guides
  • 5.2 Soil and Site Treatments
    • 5.2.1 Fertilizers
    • 5.2.2 Tillage
    • 5.2.3 Mulches
    • 5.2.4 Topsoil
    • 5.2.5 Organic Matter Amendments
    • 5.2.6 Lime Amendments
    • 5.2.7 Beneficial Soil Microorganisms
    • 5.2.8 Topographic Enhancements
  • 5.3 Obtaining Plant Materials
    • 5.3.1 Collecting Wild Seeds
    • 5.3.2 Collecting Wild Cuttings
    • 5.3.3 Collecting Wild or Salvaged Plants
    • 5.3.4 Nursery Seed Production
    • 5.3.5 Nursery Cutting Production
    • 5.3.6 Nursery Plant Production
  • 5.4 Installing Plant Materials
    • 5.4.1 Seeding
    • 5.4.2 Hydroseeding
    • 5.4.3 Installing Cuttings
    • 5.4.4 Installing Plants
  • 5.5 Post-Installation Care of Plant Materials
    • 5.5.1 Introduction
    • 5.5.2 Animal Protection
    • 5.5.3 Shade Cards
    • 5.5.4 Tree Shelters
    • 5.5.5 Irrigation
• Chapter 6: Monitoring
  • 6.1 Introduction
  • 6.2 Developing a Monitoring Plan
    • 6.2.1 Outlining the Reason for Monitoring (Purpose)
    • 6.2.2 Determining the Intensity (Intensity)
    • 6.2.3 Identifying the Needed Expertise (Who)
    • 6.2.4 Determining Monitoring Frequency (When)
    • 6.2.5 Delineating Sampling Locations (Where)
    • 6.2.6 Determining Parameters to be Monitored (What)
    • 6.2.7 Selecting Monitoring Procedures (How)
    • 6.2.8 Logistics
  • 6.3 Plant and Soil Monitoring Procedures
    • 6.3.1 Soil Cover
    • 6.3.2 Species Cover
    • 6.3.3 Species Presence
    • 6.3.4 Plant Density
    • 6.3.5 Plant Attributes
    • 6.3.6 Sampling Unit Design
    • 6.3.7 Analyze Data
  • 6.4 Pollinator Monitoring Procedures
    • 6.4.1 Bee Abundance Monitoring Procedure
    • 6.4.2 Bee and Butterfly Diversity Procedure
    • 6.4.3 Monarch Butterfly Reproduction and Habitat Procedure
    • 6.4.4 Pollinator Plant Monitoring
  • 6.5 Photo Point Monitoring Procedures
    • 6.5.1 Establishing Photo Points for Long-Term Monitoring
    • 6.5.2 Establishing Photo Points from Historic Photographs
  • 6.6 Developing a Monitoring Report
• Chapter 7: Operations & Maintenance
  • 7.1 Introduction
  • 7.2 Decision Process for Treating Unwanted Vegetation
    • 7.2.1 Inventory of Roadsides
    • 7.2.2 Defining Roadside Objectives
    • 7.2.3 Evaluating Treatment Options
    • 7.2.4 Establishing a Vegetation Treatment Plan
    • 7.2.5 Monitoring Treatments
  • 7.3 Vegetation Treatment Options
    • 7.3.1 No Action
    • 7.3.2 Mowing
    • 7.3.3 Manual Removal
    • 7.3.4 Herbicides
    • 7.3.5 Grazing
    • 7.3.6 Fire
    • 7.3.7 Biological Control
    • 7.3.8 Mechanical Removal
    • 7.3.9 Haying
  • 7.4 Prevention
    • 7.4.1 Maintaining a Weed-Resistant Roadside Environment
    • 7.4.2 Treating Disturbances for Quick Recovery
  • 7.5 Protection
• Chapter 8: Case Studies
  • 8.1 I-35 Corridor (aka "The Monarch Highway") Case Studies
  • 8.2 Florida resolves to protect wildflowers on roadsides
  • 8.3 Mapping and planning benefit Washington State pollinators
  • 8.4 Establishing native plants in Arizona
• References

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