A method for soil quality assessment in the metropolitan greenery: A comprehensive view of ecosystem services and soil functions

The soils in urban greenery considerably contribute to providing ecosystem services. However, appropriate tools to assess and manage urban soil quality under consideration of ecosystem services and soil functions are unavailable. In this study, we aimed to 1) provide detailed instructions for assessing a novel urban soil quality index (uSQI) and 2) propose the application of uSQI in urban soil quality management. The uSQI is the average of the scores for six soil functions. Each soil function was estimated by several measurable indicators that have high correlation with soil functions. The measurable soil indicators are bulk density, saturated hydraulic conductivity, litter-layer depth, mineral-associated organic matter, clay + silt content, inorganic nitrogen concentration, fluorescein diacetate hydrolytic activity, cation exchange capacity, concentrations of potentially toxic elements, and pH. The uSQI effectively identified the soils with low quality due to disturbances. The radar chart of six soil functions comprising uSQI could suggest the direction of management for urban stakeholders. • The uSQI represents soil functions necessary for urban greenery to provide ecosystem services. • The uSQI successfully identified the soils with low quality due to disturbances.