A methodology to better understand the pedoclimate of urban green spaces and its relationship to soil biodiversity

Most soil ecology studies focus on natural or agricultural environments, with limited attention paid to urban soils. However, soils provide many functions and services in cities, such as a medium for plant growth, a foundation for buildings, a source and sink for water and pollutants, and a habitat for biodiversity. On the other hand, most existing studies focus on specific taxa, ecosystems, or single climatic variables, leading to specific results. However, urban soils are particularly complex and heterogeneous, providing diverse habitats.

The aim of this research is to provide knowledge on urban soil ecosystems, with a specific focus on the pedoclimate of green spaces. The proposed approach shifts the focus from organisms to their habitat: the soil. First, the study investigates how the urban microclimate influences the pedoclimate by varying meteorological factors (e.g. period of year, air temperature, relative humidity, wind speed, etc.), built and green components, and soil properties (thermal and aerodynamic). The impacts are analysed in terms of pedoclimatic heterogeneity, sensitivity, and the dependence of these responses on the aforementioned factors. For this purpose, a simple dynamic thermo-hydric soil model has been developed that calculates several temperature and moisture indicators at different depths. A comprehensive multi-parametric analysis was then carried out, revealing key factors influencing the pedoclimate and highlighting its heterogeneity.

Secondly, an experimental campaign is about to start in an urban green space in Lyon, France. This campaign will not only measure pedoclimatic variables (temperature and humidity), but will also provide data on soil biological activity based on the Biofunctool® protocol. This will enable to compare model results with field measurements and to discuss the relationships between pedoclimate and soil biodiversity. The expected complete results will provide valuable insights to guide the design and management of urban green spaces that promote the preservation of soil biodiversity.