A Mechanistic, Individual-Based Model to Simulate Urban Tree Growth and Ecosystem Service Dynamics
1
Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Via Ponzio, 34/5, Milano, - 20133, Italia
2
, National Biodiversity Future Center, Piazza Marina, 61, Palermo, - 90133, Italia
Urban forests play a central role in supporting biodiversity and providing ecosystem services such as carbon storage, air purification and runoff mitigation. However, current models used in urban contexts are often static or oversimplified, limiting their ability to represent ecological dynamics and to inform long-term planning under changing environmental conditions. We present a dynamic, individual-based model for urban trees that simulates growth and ecosystem service provision over time. The model is explicitly species-specific and mechanistic, describing key physiological processes such as photosynthesis, phenology, and energy allocation to aboveground and belowground compartments. These processes are driven by exogenous variables including temperature, solar radiation, precipitation, and air pollution. The model operates at mixed temporal resolution (daily to hourly), allowing for the representation of both slow trends and rapid responses. Ecosystem services such as carbon sequestration, air filtration and heat mitigation are estimated as emergent outcomes of tree functioning. Model parameters are calibrated for four common and diverse species in Milan, using data from literature and open datasets. We tested the model on realistic planting scenarios, comparing historical trends with strategies optimized for species diversity. Results show how species composition and design choices affect long-term ES supply, offering insight for urban forest planning. The approach permits to account for the simulation of tree-to-tree interactions, such as competition for light and space, to capture feedbacks between individuals and improve spatial realism. This model provides a process-based framework to evaluate ecological functioning and offers practical support for decision-making in urban green infrastructure design.
Capitale naturale, servizi ecosistemici e contabilità ambientale
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