Background Europe has 181 urban areas with at least 200 000 inhabitants. Southern Europe has 26 of these and around 10 times as many cities with at least 100 000 inhabitants. Many have expanded rapidly as a result of recent (im)migration to cities. New urban areas often start as places of temporary residence for people looking to work in the city but avoid city-centre rents. However, as local services - including schools, hospitals, shops and leisure establishments – emerge, the population becomes more settled. Yet, the construction of new residential zones - and industrial zones surrounding large capitals - is typically characterised by rapid urban planning in which very few green spaces (e.g. parks) are included. The dry climates of southern Europe are challenging for the quality of soils, air and water, with desertification a real threat and the water requirements for restoring green spaces high. The result is often cities with arid conditions, surrounded by industrial zones of polluted or very poor soil, with almost no vegetation, sometimes placed in valleys affecting air quality. The CO2 balance and air pollution in these areas is amongst the worst in Europe. Objectives The LIFE-QUF project aims to promote the reforestation of southern European cities through the design and development of a key demonstration project in the Spanish city of Valladolid. It hopes to test and demonstrate the feasibility of combining forestation-related techniques to make an important contribution to the improvement of the quality of life and environment of the arid urban areas of southern Europe. The project will test the effectiveness of water retainers and mycorrhiza for enabling tree growth without any additional water infrastructure. It will plant 30 000 trees in four groups to test the benefits of the proposed techniques: with water retainers; inoculated with mycorrhiza; combining mycorrhiza and water retainers; and a control group. All four groups will be monitored using a network of sensors. The project aims to publish a final document setting out rules, recommendations, methods and techniques for obtaining the best benefits of using mycorrhiza and water retainers to promote reforestation of different types of soil. The document will include information on the experiments conducted within the project and results achieved and the cost of the techniques recommended. It will be made available to all relevant cities. The project will also create a network of ‘green’ southern European Cities known as the GSEC Group. This will exist to encourage the exchange of experiences and learning around quick reforestation of arid and polluted environments. It will also create a pressure group to support legislative and funding decisions to encourage reforestation techniques around arid cities. Expected results: The planting of 30 000 trees in the south of Valladolid using a range of innovative techniques; A 95% survival rate for trees planted without water infrastructure; A survival rate at least 30% higher than when using no technology, with a corresponding improvement in biodiversity and soil quality; A 20% increase in the average tree biomass, with a corresponding increase in CO2 absorption; Capture of at least 6 tonnes of CO2 during the first two years of the project, with significantly higher capture in subsequent years; A 10% reduction in noxious gases and particles in the atmosphere (CO, lead, etc.); An increase of at least 1% in organic matter in soil; The publication of a guide to reforestation of arid areas; and The creation of the GSEC Group, a network of Green Southern European Cities.