On November 21 and 22, 2019 the second World Forum On Urban Forests Two days of ideas and actions for new forests within cities and countries around the world was held in La Triennale di Milano. The conference organised by FAO, Politecnico di Milano and SISEF brought together the main personalities of the scientific research and public administrators dealing with the urban forest sector. It was inaugurated by the Prime Minister Giuseppe Conte who stressed, with emphasis, the great importance of the sustainable forest management. The event was also attended by the CNR, represented by the Director of the Research Institute on Terrestrial Ecosystems (IRET), Dr. Carlo Calfapietra who for years has been carrying out projects aimed at improving the quality of life in urban areas with the use of green infrastructure. On this occasion, Dr. Calfapietra with his speech What research for the functional quantification of green infrastructure ecosystem services? highlighted the role of scientific research in the context of urban planning projects.