Evaluating Vegetation Performance of Innovative Modular Green Roof System: a Hyperspectral Imaging Approach

Green roofs (GRs) contribute to the mitigation of Climate Change byreducing urban heat island effects, and enhancing carbon sequestration in thebuilt environment. Recent developments in modular GR systems employinginnovative materials can facilitate their widespread adoption, by overcominglimitations related to complex installation and high maintenance processes.However, GRs performances depend strongly on the vegetation conditions. Thepresent study explores the use of Hyperspectral Imaging (HSI) to monitor in vivothe physiological status and performance of vegetation across different plantspecies grown on an innovative clay-based tile designed for GRs applications. SinceHSI data can be processed through simple spectral indices, this technology hasbecome increasingly effective for non-destructive vegetation monitoring. Theanalysis of Vegetation Indices (VIs), derived from HSI data, was coupled with realtime in vivo gas exchange measurements of photosynthetic CO2 assimilation rates,under environmentally controlled conditions. Results show distinct spectralbehaviour between drought-stressed and healthy plants. NDVI showed highsensitivity to early stress, declining by 8% when CO₂ assimilation decreased byonly 32% in Trifolium-based CAPT-TILEs. HSI can serve as a non-invasive tool formonitoring the GR performance related to CO2 mitigation. This can assist inselection of plant species aimed at the development of innovative GR system. Inaddition, future applications of this monitoring system could enable the creationof predictive models to anticipate potential vegetation stressful conditions, andallow timely maintenance interventions. Expanding the monitoring methodologyto real-world roof installations will further enable the understanding of vegetationresilience and optimize GR systems.