Urban Green Spaces Restoration Using Native Forbs, Site Preparation and Soil Amendments—A Case Study

Abstract

Restoration of urban green spaces with native flora is especially important for promoting various ecosystem services. Although there have been years of research on land reclamation, ecological restoration and plant establishment, there is a lack of knowledge on how to reintegrate the native ecological component, specifically forb species in urban green spaces. We evaluated the restoration potential of 24 native forbs using different site preparation (herbicide, tillage, herbicide with tillage and control) and soil amendment (100% compost, 50% compost with 50% topsoil, 20% compost with 80% topsoil and control) treatments in a recreational park in Edmonton, Alberta, Canada. Soil texture and nutrients generally increased with increased compost application rate; some declined within a year, others increased. Based on survival and growth analysis, the forb species with the highest potential for use in urban green spaces were Penstemon procerus, Fragaria virginiana, Heuchera cylindrica, Agastache foeniculum, Antennaria microphylla, Mentha arvensis and Geum aleppicum. Native forb species response was more prominent with soil amendment than site preparation. Treatments with greater amounts of compost had greater survival, growth, species richness, cover and noxious weed cover than control treatments. This study suggests amendment of soil with compost can positively influence forb species restoration in urban green spaces; under some conditions site preparation may be required.