Tree tracking. Species selection and traceability for sustainable and biodiversity-friendly urban reforestation

The current climate change and increasing climate variability represent a serious global challenge that demands urgent responses. Among the multiple actions that should be taken, afforestation and reforestation are the most common strategies. The current paper aims to assess the potential of tree species to be used in urban forestry in the Po Plain ecoregional province (Northern Italy) using DNA barcoding approach for plant traceability and ecophysiological indexes (shade, drought and waterlogging) for plant selection. DNA barcoding markers results showed a 55.5% of success, but the power of discrimination increased to 94.5% when considering only the autochthonous ecoregional species pool. Concerning ecophysiological markers, Fagus sylvatica, Abies alba, Picea abies and Taxus baccata were very shade-tolerant. The best performing trees concerning drought tolerance were oak species (Quercus ilex, Q. pubescens and Q. cerris), pines (Pinus pinea, P. nigra and P. sylvestris) and Fraxinus ornus. Only a few tree species (Salix alba, Alnus glutinosa, Populus nigra and Prunus padus) showed high tolerance to waterlogging. The combination of both approaches makes it possible to select the most suitable species, based on eco-pedological and microclimatic conditions, and to trace their identity along the entire supply chain, from nursery to planting, for urban forestry.