PubMed · 2026-06-17
Researchers tested five native tree and shrub species on highway construction waste stabilized with lime, finding that species choice matters far more than soil amendments for getting plants established on these harsh, alkaline substrates.
Flowering ash (Fraxinus ornus) and hazel (Corylus avellana) showed the highest survival and growth across all substrate treatments over 3 years, making them the strongest candidates for lime-stabilized spoil restoration.
Downy oak (Quercus pubescens) suffered the highest mortality and lowest growth, indicating it is poorly suited for direct planting on alkaline spoil without substrate preconditioning.
Organic amendments (compost, anaerobic digestate, olive pomace) did not significantly boost plant growth or survival — doses were likely too low for nutrient-poor conditions — but did help reduce pH at the critical topsoil–spoil interface.
