Drastically Disturbed Soils Mitigation
SR-73 Roadway Slope Revegetation
SR-73 Slope Revegetation Management and Monitoring, Orange County, California – Transportation Corridor Agencies
The drastically disturbed soils adjacent to the SR-73 toll road presented several challenges for revegetation. Most fill slope soils were subsoil that required an ecological approach to soil amendments and seed application. The cut slopes required similar treatments. NewFields designed the ecological approach to revegetate these roadway slopes using the adjacent existing coastal sage scrub habitat as a reference. The revegetation process included amending the soils with arbuscular mycorrhizal (AM) fungi, as well as a slow release, specially formulated fertilizer in conjunction with a native seed mix that included early colonizing species, all designed to jump-start natural soil processes. This project pioneered and documented the successful application of AM fungi in the hydroseed.
NewFields conducted oversight of the restoration implementation and monitored the soil and vegetation conditions of the site. After six years, the site demonstrated a self-sustaining costal sage habitat. Federally-listed California gnatcatchers started using the slopes within 4 years of seeding and planting. Soil monitoring was incorporated into an independent study program in habitat restoration at Irvine Valley College where students learned to identify and measure AM fungal colonization in plant roots, and study sites with different revegetation/restoration plans.