Passive Roadside Restoration Reduces Management Costs and Fosters Native Habitat

Abstract

Roadside ecosystems are managed areas adjacent to roads that are undervalued for the ecological functions they provide. Reductions in roadside mowing is a passive restoration approach that can create habitat, lower management costs, and reduce fragmentation, but managers fear reducing mowing will allow invasive plants to proliferate. Our goal was to quantify changes in invasive plant cover due to decreased mowing. We compared plant diversity and percent cover at roadside sites under three types of vegetation management in Rhode Island—Reference (no-mow forested roadsides, n = 5), Restored (reduced mowing plan, n = 5), Mowed (traditional mowing plan, n = 5)—at four spatial scales using Modified-Whittaker vegetation surveys. Reference sites had the highest native species richness at two spatial scales, the lowest introduced species richness at three spatial scales, and the lowest introduced species percent cover. Invasive species diversity and abundance was not affected by mowing treatment. Because we did not observe an increase of invasive or introduced plant species at sites which are transitioning from Mowed to Restored, we recommend roadside managers implement passive roadside restoration wherever possible. Additionally, because Reference sites had significantly higher native plant diversity and lower introduced plant diversity and cover, managers may consider allowing roadsides to continue through the stages of succession and transition to young forests. Alternatively, managers could restore roadsides to varying stages of succession to increase habitat heterogeneity. These kinds of roadside management plans facilitate biodiversity, maintain habitat important for rare and endangered wildlife, can decrease atmospheric CO₂ emissions, and are a cost-effective form of restoration.