The Effect of Turfgrass-to-Meadow Restoration on Carbon Storage and Sequestration in an Urban Environment

Abstract

Since 2013, Toronto and Region Conservation Authority has been restoring a 16 km hydro corridor in Scarborough, Ontario, actively removing turfgrass and replacing it with meadow. The primary intention of this project, known as The Meadoway, is to improve biodiversity and habitat connectivity in the city, but there is the potential for other co-benefits such as enhanced carbon storage and sequestration. We made use of the section-by-section restoration timeline in a space-for-time substitution to evaluate changes with time since restoration in three categories: unrestored turfgrass, recently restored meadow (restored in 2020-2024), and older restored meadow (restored in 2013-2016). First, we measured CO2 and CH4 fluxes biweekly to make estimates of daily net ecosystem exchange, gross primary production, and ecosystem respiration. We found that, cumulatively, both recent (−12.5 ± 19.1 mol m⁻² season⁻¹) and old meadow (−12.3 ± 6.44 mol m⁻² season⁻¹) acted as carbon sinks while unrestored turfgrass (+14.1 ± 17.0 mol m⁻² season⁻¹) acted as a net carbon source over the course of our sampling season. Next, we conducted a 366-day plant litter transplant experiment to investigate whether decomposition rates differ due to litter quality, site conditions, or a combination of both. We found that meadow litter decomposes 33.6% more slowly than turfgrass litter regardless of site, but all litter decomposed 34.7% more at recent meadow sites compared to turfgrass sites. We measured biomass production over the growing season by clipping aboveground biomass and using a modified soil ingrowth core method belowground. We found 272% greater aboveground biomass standing stock, and 213% higher belowground plant production in old meadow compared to turfgrass in 2025. Finally, we measured belowground carbon stocks, using a loss-on-ignition method to measure soil organic matter, soil carbonate content, and root organic matter. We found largely similar belowground carbon stocks in restored meadow as in turfgrass, with the important exception that the old meadow category had 22.4% lower surface soil organic matter compared to turfgrass. We lack baseline data on pre-restoration soil organic matter and suspect this is attributable to antecedent differences between the sections. In total, we provide convincing evidence that urban turfgrass-to-meadow restoration provides valuable climate mitigation co-benefits and could be considered a nature-based solution to climate change.