Soil sealing at ‘tree catchment scale’: Impact of soil sealing on the water availability for urban trees

• Applicant: Dr. Moreen Willaredt
• Subject Area: Soil Sciences ; Physical Geography
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529031514

The overarching objective of the research project is to analyze the impact of urban soil sealing on water availability for urban trees in arid cities and cities in a changing climate. For this purpose, the new spatial concept of the 'tree catchment scale' will first be developed and used to map and quantify the current state of soil sealing at the local tree level in two cities; Sacramento, USA and Berlin, Germany. High-resolution spatial datasets, so-called digital representations of public street space, will serve as the basis for this analysis. The new soil sealing datasets will be used to locate mature tree individuals for a field study in Sacramento, USA with the purpose to investigate their growth in relation to the high-resolution degree of soil sealing in the tree catchment, but also their location in the urban heat island. Additionally, an urban process-based numerical soil-plant-atmosphere model will be developed that integrates both the anthropogenic interface of soil sealing and, for the first time, the underlying root water uptake. Modelling of the soil water balance under different sealing materials is facilitated by a unique available dataset of soil moisture, obtained under numerous pavement materials. The extension of the numerical model to include root water uptake will be calibrated and validated using a field experiment with trees, with and without soil sealing. The model will serve for simulation studies analyzing the role of the climatic boundary conditions on the impact of soil sealing on the water availability for urban trees. The project is significant for the preservation of mature urban trees, which make an important contribution to the adaptation of urban space to climate change and are particularly useful in mitigating health risks to vulnerable populations during heat waves. The project results provide new knowledge that is an essential component for the implementation of a resource-efficient water supply for urban trees.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professor Dr. Alessandro Ossola