Evaluating the Success of Ontario Roadside Restorations - An Ecosystem Approach

Abstract

Ecological restoration, or assisting the recovery of damaged ecosystems, is recognized as a crucial activity for reversing biodiversity loss across the globe. Roadside rights-of-way may be suitable areas for the restoration of endangered grassland communities, because they occupy significant areas of underutilized land, are managed as early successional plant communities, and may serve as corridors for wildlife movement and gene flow. However, though many roadside restoration projects have been undertaken in North America, few studies have evaluated their long-term success and most monitoring is narrow in scope. True restoration includes restoring an appropriate species composition, vegetation structure and ecosystem functions, and thus these ecosystem components must be measured when evaluating success. I assessed the plant community, bee community, soil carbon and plant-fungal relationships at roadside restorations of various ages along three major highways in Southern Ontario and compared these measures to unrestored roadsides and reference sites. I found that roadside restorations successfully increased native plant richness, though not to the level of a remnant grassland. Bee communities varied mostly by highway rather than site type, though bee abundance was positively correlated with plant diversity and bare ground. Soil carbon in roadside sites was similar to that of a remnant grassland but did not differ among restored and control sites. Plant growth response to arbuscular mycorrhizal fungi collected from roadside sites varied depending on the site and showed a weak negative correlation with site age. Taken together, these results suggest that roadside restoration can benefit some ecosystem components, but simply seeding native plants along roadsides may not be sufficient for improving ecosystem function. This study highlights the importance of evaluating success in a comprehensive manner that includes multiple ecosystem components.