Linkages between plant functional diversity and soil-based ecosystem services in urban and peri-urban vacant lots

Initiatives to repurpose vacant lots to improve people's well-being are increasing worldwide. Still, little is known about how distinct plant communities influence the provision of ecosystem services in vacant lots. To bridge this gap, we investigated associations in vacant lots between land-cover type, plant diversity (both taxonomic and functional), and composition with soil organic carbon and hydraulic conductivity which are indicators of carbon storage and stormwater runoff control. We sampled plant communities, soil organic carbon, and hydraulic conductivity across 50 sites, three plots per site, in the Greater Quebec City Area, Canada. The sites comprised five land-cover types: lawn, bare soil, low- and high-density herbaceous vegetation, and sparse trees. Soil organic carbon was lowest in bare soil lots, while the lowest hydraulic conductivity was found in lots with sparse trees and high-density herbaceous vegetation. Soil organic carbon was positively correlated with forb and total plant cover, but negatively correlated with functional dispersion. Hydraulic conductivity was positively correlated with taproot frequency and functional dispersion of three traits (lifespan, specific leaf area, and reproductive modes), but negatively correlated with grass and total plant cover. This research highlights the associations between plant functional traits and groups with soil characteristics, uncovering patterns that might be overlooked if only land-cover was considered, such as higher carbon storage and hydraulic conductivity associated with forb-rich meadows with high taproot frequency. We advocate for a trait-focused approach in vacant lot revitalization, particularly when the goal is to enhance local levels of soil-based ecosystem services.