Assessing Seed Mixtures for Roadside Revegetation – Richness and Origin as Predictors for Erosion Control

Abstract

Roadside revegetation practices have evolved significantly in recent decades, spurred by the need for more reliable and cost-efficient operations and escalating concerns regarding biodiversity integration into large land-planning projects. While the use of rich and locally-sourced seed mixtures for revegetation is being considered with a rising interest to provide ecosystem services and resiliency, their efficacy in meeting practitioners’ erosion-control expec - tations remains underexplored. This study addressed this gap by investigating the erosion-control potential of six seed mixtures, categorized into three compositions with varying levels of richness (standard < competitive < bio-diversity) and sourced from local and non-local origins, in a controlled greenhouse environment. For this purpose, the effect of these modalities on vegetation cover, plant density and root biomass production was assessed over a period of 118 days. During the establishment phase, while the effect of the origin on cover was not conclusive, the richer Biodiversity composition achieved faster ground cover, attributed to the presence of large-leaved forbs. The overall density of plants was lower in the richer mix compared to the two others, but significantly higher in its local version. The findings underscored trade-offs between vegetation cover and density, driven by intra-and inter-specific competition processes, particularly related to access to light. Root biomass production was influenced by the origin of the seeds, with local mixes yielding higher biomass, particularly visible in the richer composition. In spite of growing conditions supposed to favor cultivars, wild and locally-sourced seeds showed promising results, advocating their broader adoption in roadside revegetation efforts. These findings provide insights for practitioners to optimize revegetation strategies and enhance roadside ecosystem resilience in the face of changing environmental conditions. In situ field trials should now be carried out to confirm these promising results obtained under controlled conditions for roadside management and ecological restoration.