Abandoned areas in the metropolitan area of Milan, whose population is over 4.1 million (2014 OECD), have recently been redeveloped. This has been an opportunity to implement green solutions when regenerating entire districts. Milan also needs to deal with traffic pollution resulting from the increased urbanisation of recent years; it poses a significant risk to human health and well-being. Reducing soil consumption is also a major challenge for Milan. More than 60 % of the soil is sealed, one of the highest levels in Italy.
Urban redevelopment was an opportunity to adopt solutions and achieve different targets through nature-based solutions. Carta of Milan, the city's strategic environmental plan, recognises ‘green infrastructure’ as the best way to achieve environmental targets, promote social development and improve social welfare. On a wider scale, the Lombardy Region manages the green infrastructure actions for ecological connections and the creation of ecosystems, ensuring continuity between the Alps and the Po Valley (Pianura Padana) and the urban environments within that area, ensured by the Rete Ecologica Regionale Plan. The plan provides guidelines to the different municipalities for the management and creation of ecosystems and outlines the funding mechanisms. Gorla Maggiore, about 30 kilometres northwest of Milan, lies in a delicate transition zone. The town and its waterpark help to improve the quality of the area's water and to better regulate the flow of water.
The city of Milan implements different nature-based solutions as part of its architectural and urban renewal strategies. Bosco Verticale (Vertical Forest) by Stefano Boeri is a showcase of advanced engineering and technological development which uses nature-based solutions as an example of sustainable urbanisation. Urban Gardening plays an important role in the city of involving people in the management of urban green spaces. Green urban areas, in particular public parks, gardens and urban forests, are created for multiple purposes. Green urban areas provide Milan with important ecosystem services while Green Rays and Green Belts are meant to connect the green areas using pedestrian/cycling green roads. Parco Agricolo Sud, a key area of the Green Belt, offers an example of people's involvement in the management of the rural landscape on the city outskirts and the use of nature-based actions in this. On a regional scale, the Gorla water park, a multi-purpose green infrastructure (a series of built wetlands surrounded by a park), offers a variety of valuable ecosystem services.
Parco Agricolo Sud (peri-urban agriculture and nature conservation)
The planning scheme of Carta of Milan included a proposal to create a green system connecting green spaces and parks throughout the metropolitan area (Green Rays and Green Belt).
Parco Agricolo Sud offers local inhabitants farming, forestry, cultural and recreational activities. The park preserves the landscape and ensures environmental recovery of the areas, connecting town and country and linking outer areas with the urban green system. It serves as an ecological balance for the metropolitan area. To ensure the protection of biodiversity, some areas have been dedicated to rebuilding ecosystems and reintroducing fauna species that are becoming rarer (such as the Lombard Spadefoot toad, the Lataste's frog, the swamp turtle and the river prawn). The area also includes nature reserves (Site of Conservation Interest — SCI and Priority Conservation Areas — PCA).
The park has different agricultural areas. It has a utilised agricultural area of 38 000 ha out of a total surface of 47 033 ha. Over 1 000 active farmers are involved. The periurban farming is of primary importance not only for soil conservation but also for food production. More and more people want locally grown food, and periurban farming can meet this need.
Urban gardening as a component of urban agriculture has grown in popularity over the last decades. In 2012 the City Council of Milan approved guidelines for agreements with non-profit organisations to create new urban gardens in the municipality in less time and at no cost to gardeners (ColtivaMi Project).
The municipality agreed to make it easier to put in new gardens in order to recover and fix up abandoned green areas. This was a way to promote gardening as a hobby, encourage social contacts, make green areas more accessible and encourage participatory management of the territory. Allotment gardens in Milan are mainly plots on public and municipal-owned land, exclusively intended for growing fruit and vegetables for private consumption. The use of the plots is subject to a municipal regulation and to the payment of a yearly fee. In most cases, the municipality provides water (Ruggeri G et al., 2016).
Bosco Verticale (Vertical Forest)
The Porta Nova project, which includes the Bosco Verticale, is a city plan (2004) to transform the urban neighbourhood (Porta Nova) into a business-residential district implementing green solutions. It is an investment totalling more than EUR 2 billion. The Vertical Forest consists of two residential towers 110 and 76 m high hosting 900 trees (each measuring 3, 6 or 9 metres) and over 20 000 plants (a wide range of shrubs and floral plants) distributed according to the sun exposure of the facade. It is estimated that the ecosystem services from the plants in the two towers (CO2 storage, air quality, biodiversity improvement) are equal to the services of 2 ha of forest (European Conference, 2014).
An experimental campaign (Buffoni A. et al., 2013) demonstrated that the vegetation in the towers was capable of reducing particulate concentration. The percentage of average abatement, due to the plants, ranged from about 30 % to 20 % for PM10 (Particular Matter) and TSP (Total Suspended Particulate) respectively. These results confirm the effective potential of trees and green barriers (shrubs and hedges) in removing airborne particulate matter. These are common features of urban forests and pocket parks, which improve the urban environment and life quality of local residents and confirm the need to preserve and increase urban vegetation (Buffoni A. et al., 2013).
Gorla Maggiore water park
The Gorla water park has been developed, with the sponsorship of the Lombardy Regional Authority and co-funding by the Fondazione Cariplo (see ‘Financing’), through a participatory process. The whole area is about 3 ha. It includes a flood prevention area (1 ha), a pollutant removal area (0.4 ha of a phragmites reed bed and 0.3 ha of natural-like multispecies wetland) and a leisure and recreational area (1.3 ha of park).
There are four sand filter vertical beds to treat the first flush from the combined sewer overflow mechanism and an extended retention basin for the accumulation and slow release in the river of the second flush. The primary aim is to protect against flooding but also to keep pollution in check. The green infrastructure therefore addresses the issue of pollution and flood control (OpenNESS, 2016).
The OpenNESS project assessed the effectiveness of the expected impacts in sampling campaigns performed during three rain events in different climatic conditions (Masi F. at al., 2017):
• ‘On-site’ treatment by CW (Constructed Wetlands) allows continuous treatment and therefore higher pollutant mass removal compared to first flush storage tanks and treatment of the stored wastewater in the main WWTP (Waste Water Treatment Plants) in the days after the end of the rain event;
• The Gorla CSO-CW guarantees satisfactorily ecological services in terms of flood protection and water quality and the discharged effluents comply with the European limits for discharge in rivers and fresh water bodies, with removal rates of about 90 % for COD and NH4+ in terms of concentrations and mass loads of 68 % and 94 % respectively in one year;
• A continuous in-line treatment (CWs or other natural solutions) has proven to be preferable to the first flush accumulation-treatment such as first flush storage tanks alone, especially if the secondary ecosystem services can work properly as boosting agents for the diffused and wide implementation of these systems in urbanised areas.
Parco Agricolo Sud
The itineraries that link the historical and architectural heritage in the park are important tools for NBS recreational and cultural activities. Looking after that heritage (rural hamlets, castles, villas and abbeys in the park) becomes another way to increase tourism in the park. Within rural heritage, there is still a highly competitive farming activity which can make the most of the land and resist urbanisation.
A study on Urban Gardeners’ Motivations (Ruggeri G et al., 2016) has shown, in interviews of different categories of residents, that in Milan most of the respondents want healthier food and personal wellness, and that is what motivates them to practice urban gardening in the city. For policy recommendations, the study (Ruggeri G et al., 2016) concludes that the great emphasis Milan gardeners put on health-related motivations for gardening should encourage more quality-related interventions, e.g. incentives for soil testing services for gardeners, the development of a real-time soil quality map of the city or the study of potential pollutant sources near the gardens. Moreover, given the interest of Milan gardeners in gardening tips, healthy food, organic production and other urban gardening practices as shown in the survey results, it could be interesting to propose innovative and experimental solutions for new forms of urban gardening that bring together the different functions of vegetable gardens. This is something that already occurs in other cities around the world.
Bosco Verticale (Vertical Forest)
Apart from CO2 sequestration and air pollution removal, the city of Milan has benefited from the attractiveness and visibility of Boeri’s Vertical Forest. The Bosco Verticale has won various awards, including the ‘High-rise Award 2014’ and the ‘CTBUH Award 2015’. Tourism in the city increased thanks to EXPO 2015, for which Milan adopted many green solutions (e.g. creation of green spaces, energy and lightening management, construction and materials, and mobility).
Gorla Maggiore water park
The Gorla water park is a multi-purpose infrastructure with a leisure and recreational area dedicated to a wide range of activities (educational activities, biking, running, picnicking for which appropriate facilities are provided, animal watching). A wide range of educational services on the local fauna (water birds and small amphibians) are available on the site and advertised on informational panels. The flora is also highlighted, especially the plants involved in water purification processes. (OpenNESS, 2016).
The monetary value of the ecosystem services was also assessed. A questionnaire was sent to the residents of Gorla Maggiore to estimate the value they assign to each of the three alternatives and their use of the different types of infrastructure. The results were analysed with econometric models. The analysis shows that local residents are willing to pay around three times more for a green infrastructure than for a grey one, and much more if it is surrounded by a recreational park. On average, the willingness-to-pay per household and per year for the existing water park is around EUR 28. Based on these results, the cost-benefit analysis of the different projects reveals that after a time span of 20 years the cost and benefits of the green infrastructure can be balanced, while for the other alternatives the economic balance is still negative (OpenNESS, 2016).
- By 2012 the system of regional parks reached 39 % of the land area in the province of Milan.
- In 2015 the city of Milan had more than 23.5 km2 of public green areas, which can be translated into 17.31 m2 of public green space per inhabitant (Source: City of Milan, 2016). These areas contain 633 recreational spots and 348 areas suitable for dogs.
- Cento Passi forest represents a unique challenge because its 17 ha were confiscated from the Mafia and ceded to the municipal administration.
- Boeri’s Vertical Forest proved to be a nature-based solution, which could be upscaled and replicated. Nanjing Vertical Forest Nanjing Green Towers, will be the first vertical forest built in Asia. It is currently being developed by Boeri. The facades will have 600 tall trees, 500 medium-sized trees (for a total amount of 1 100 trees from 23 local species) and 2 500 cascading plants and shrubs, covering 6 000 m2. A real vertical forest, helping to regenerate local biodiversity, will absorb 25 tonnes of CO2 each year and produce about 60 kg of oxygen per day (Boeri S., 2017).
- Mariani L. et al. (2016) have shown that increasing and optimising single components of park structures can improve the cooling effect of urban parks in Milan (See Impacts of EU research and innovation projects in the city).
The city of Milan supports partnership with private or semi-private companies for the maintenance of its green areas. ‘Adotta il verde pubblico’ (Adopt a green area) is a city initiative to encourage local residents to become involved in the administration of green areas and to seek sponsorship to help the city’s finances. Milan already started 396 partnerships (up to April 2016) for a total of 116 127 m2 of surface.
In Milan there are several initiatives in which local stakeholders have participated according to the objectives of the public authorities, such as BoscoinCittà Park and Cesano Maderno Oasis.
With its development, implementation and effectiveness, the Gorla water park is a virtuous example of a nature-based solution. The Gorla water park has been developed through a participatory process with public-private sponsorship. It serves as a multi-purpose infrastructure, since it includes a flood prevention area, a pollutant removal area and a leisure and recreational area. The Gorla example also shows how the EU's research and innovation funding strategy could be beneficial for the city's administration, since the OpenNESS project conducted an in-depth analysis on the site showing the positive impact of environmental protection and social support (see Impacts and Multiple Benefits of Gorla Maggiore Water Park).
The Lombardy Region, through Regulation ‘D.d.u.o. 22 Dicembre 2016 - n. 13767’, manages a EUR 4 million funding scheme for ‘Infrastrutture verdi a rilevanza ecologica e di incremento della naturalità’ (‘Green infrastructures for ecological connection and ecosystem creation’). Individuals and legal entities — public or private — can apply for a maximum of EUR 30 000 per hectare for initial interventions and EUR 4 000 per hectare per year for maintenance costs, up to a maximum of 3 years.
Eligible actions are those involving the creation of green areas whose focus is mainly the development of forest ecosystems, soil restoration and conversion. Financing for the purchase of soil is reserved for public entities (city administrations, parks, regional reserves).
In 2007 - 2013 the Lombardy Region invested a total of EUR 61.2 million (Source: Prioritized Action Framework for Natura 2000, 2016). Part of the money (EUR 28 million) came from EU funds (Life+, European Agricultural Fund for Rural Development, European Regional Development Fund) and part from Regional funds (EUR 31.6 million).
Private funds are also available. In 2016 the Fondazione Cariplo, a ‘foundation that helps social and civil organisations better serve their own community’, funded a EUR 3.7 million call for proposal to develop large-scale green corridors. The amount funded per project ranged from EUR 450 000 to a maximum of EUR 750 000.
The total annual amount for the ordinary maintenance of public green spaces is EUR 17.5 million (EUR 1.01 per m2 per year) while extraordinary maintenance (e.g. replanting or renovation of installations) accounts for about EUR 2.5 million (Source: City of Milan, 2016).
The Lombardy Region developed an ecological network, ‘Rete Ecologica Regionale’ (RER, Regional Ecological Network), acknowledging the isolation of ecological areas and land fragmentation, which represent a high risk for biodiversity and natural habitats. The objective is to maintain and restore a connection between the flora and fauna where fragmentation occurs. The ‘Rete Ecologica Regionale’ was approved in 2009 and sets out primary elements which are the areas identified as priority for biodiversity. The ecological network was designed using the maps of 73 priority areas for biodiversity and complemented with the other elements constituting networks such as ecological corridors and road networks (Green Infrastructure, 2016).
The planning system of the city of Milan is managed by the Lombardy Region — General Directorate for Landscape, Urban Planning and Soil Conservation and by the municipality of Milan. Metropolitan Milan is administered by ESRAF (Ente Regionale per i Servizi all’Agricoltura e alle Foreste) in conjunction with the regional government of Lombardy and surrounding cities to ensure an integrated development process
Land and water resource planning is under the authority of the Lombardy Region. To implement the environmental quality objectives, the Region has adopted river contracts as local strategic planning instruments in different sub-basins, involving the local authorities (provinces, communes) and institutional stakeholders (such as the Regional Environmental Protection Agency, ARPA Lombardia, and the Po River Basin Authority). The overall objective of the planning instrument is to implement the requirements of the Water Framework Directive, involving the local institutional players and better integrating the sectorial planning strategies (Grizzetti B. et Al., 2016).
The city of Milan is responsible for evaluating and implementing the different plans. The most recent results are available on the city of Milan's website. The green areas and agriculture department (Settore Verde e Agricoltura) is responsible for the maintenance and regeneration of the green areas and new interventions. It also manages the relationship between the city and local farming communities.
The Lombardy Region has a monitoring system to analyse the impact of the actions financed on green connections and the creation of ecosystems. Green areas and connections are the subject of a periodic strategic environmental assessment and environmental impact assessment by the Region. The assessment is based on a set of indices such as ecosystem quality, ecosystem production, and anthropic pressure. The regulation D.G.R. n. 8/2512 e delle Linee guida per la Valorizzazione del Territorio Rurale lays down the general guidelines for monitoring and evaluating the green areas and their ecosystem services. To assess whether the objectives have been achieved, performance indicators are used on the projects financed under Regulation ‘D.d.u.o. 22 Dicembre 2016 — n. 13767’.
Green Surge worked with Milan's ‘Settore Agricoltura e Foreste’ (Agriculture and Forestry department, now UTR Citta’ Metropolitana). Green Surge met and interviewed city officials to assess the efforts by Milan to replant trees over the last 20 years.
In particular, Green Surge collected information on the planning and governance of urban green spaces in Milan (first questionnaire) and on participatory planning and stakeholder involvement (second questionnaire). Green Surge used this information to develop the case study for the city of Milan. Green Surge's assessment generated an added value since it allowed the city to self-assess and compare its green strategy with other realities. City officials also recognised the benefit of knowledge gained from working with the project consortium, which was set up when drafting the new action plan ‘Piano ad indirizzo forestale della Provincia di Milano’ (2017).
Green Surge assessed the mitigating effect of vegetation on the urban heat island of Milan (Mariani L. et al., 2016). An hourly energy balance model was used to evaluate the time and space behaviours of the urban heat island effect. Five different sites (rural, urban park, sites located in canyons of the urban plateau, and urban peak) of the metropolitan area of Milan were selected and modelled to highlight their specific urban heat island intensity.
In conclusion, the study clearly showed that increasing and optimising single components of park structures can improve the cooling effect of urban parks. The results of this investigation illustrate the importance of conducting future in-depth analyses of rural-urban or built-up park transects.
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Buffoni A., Silli V., Manes F. (2013) Air pollution removal by urban green in Milan town centre -
Results from model estimations and air quality measurements. 16th Forum on Urban Forestry, Milan 11 May 2013.
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Giacomello E., Valagussa M. (2014) Vertical densification of nature: Monitoring Research of the Bosco verticale in Milan, Italy. CTBUH International Research Seed Funding. Chicago: CTBUH.
Grizzetti B. et al. (2016) Ecosystem services for water policy: Insights across Europe. Environmental Science & Policy 66 (2016) 179-190. FP7 project OpenNESS.
Lafortezza R., Davies C., Sanesi G., Konijnendijk C.C. (2013) Green Infrastructure as a tool to support spatial planning in European urban regions. iForest 6: 102-108 (suppl. 2): s1-s3 — doi: 10.3832/ifor0723-006.
Liquete C. et al. (2016) Integrated valuation of a nature-based solution for water pollution control. Highlighting hidden benefits. Ecosystem Services 22 (2016) 392-401. FP7 project OpenNESS.
L. Mariani, S.G. Parisi, G. Cola, R. Lafortezza, G. Colangelo, G. Sanesi (2016) Climatological analysis of the mitigating effect of vegetation on the urban heat island of Milan, Italy. Science of the Total Environment 569-570 (2016) 762-773. http://dx.doi.org/10.1016/j.scitotenv.2016.06.111
Masi F., Rizzo A., Bresciani R. and Conte G. (2017) Constructed wetlands for combined sewer overflow treatment: Ecosystem services at Gorla Maggiore, Italy. Ecological Engineering 98 (2017) 427-438. FP7 project OpenNESS.
Mell I. (2016) Global Green Infrastructure: Lessons for successful policy-making, investment and management. Routledge, 2016. 224 pages. ISBN 1317520564, 9781317520566.
Municipality of Milan (2009) Sustainable Energy and Climate Action Plan. Milan, Italy.
Municipality of Milan (2016) Forest Management Plan. Milan, Italy.
Reynaud A., Lanzanova D., Grizzetti B. and Liquete C. (2016) Going Green? Economic Valuation of a Multipurpose Water Infrastructure in Northern Italy. FP7 project OpenNESS.
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Websites (Access March 2017)
Agricity Milano Metropoli Rurale. Available online: http://www.agricity.it/pagina-di-esempio/coltivami/
OpenNESS Case Study LINK