Integrating urban soil quality into spatial planning: a comparative review of indicator frameworks and indices in urban and peri-urban areas

Urban soils are often neglected in spatial planning and management due to limited awareness of their properties, functions and ecosystem services (ES). Even the European targets of “no net land take” and “no net soil sealing” focus only on quantitative aspects, neglecting soil quality (i.e., the capacity of soil to function effectively within ecosystems and land uses). Explicitly integrating urban soil properties, functions and ES into spatial planning could help minimise negative impacts while promoting compensation and restoration measures that enhance environmental and human well-being. This gap has also been highlighted in the Outlook on the knowledge gaps to reduce soil sealing and increase the reuse of urban soil, published by the SOLO (Soils for Europe) project, funded by the EU Soil Mission.

This study compares indicator frameworks and indices that consider properties, functions, and ES of urban soils to support planning and management. From a systematic search through scientific databases, four frameworks were identified, some of which were described in more than one publication. The screening criteria considered were: the links established between soil properties, soil functions, and ES; the methods proposed for their assessment; and the type of application in planning and management.

In the selected frameworks, soil properties were measured either in situ or in the laboratory and used as inputs or proxies to evaluate soil functions. Pedo-transfer functions were applied to establish relationships between soil properties and functions, while links between soil functions and ES were derived from literature analysis and expert knowledge. The frameworks primarily considered regulating ES, especially those related to climate and water regulation, followed by provisioning services. Urban soil quality indices were developed based on soil functions and ES, using averaged or weighted aggregation methods. These indices aim to monitor urban soil management and provide soil information to support spatial planning.

By identifying indicators and methods, the study supports an assessment of urban soil quality that can inform decisions to reduce and compensate for soil function losses caused by urban development. Additionally, it promotes the identification and protection of high-quality soils, contributing to more sustainable urban development in spatial planning.