To make cities more sustainable, resilient, healthy and pleasant places, investing in green spaces is essential. All the more so given that more than half the world's population already lives in urban centres today — a share that will rise to 70 per cent by 2050. Last March, on the occasion of the International Day of Forests, the FAO had stressed the issue, pointing to a way to "reinvent" cities. "Forests and trees, if well managed, within and around urban centres provide habitat, food and protection for numerous animals and many plant species. This also helps to safeguard and increase biodiversity," José Graziano da Silva, Director-General of the United Nations agency, had noted.

Watch all the interviews at Wfuf 2018

• Hiroto Mitsugi, head of the FAO forestry department
• Giorgio Vacchiano, researcher
• David Miller, C40
• Francesco Garofalo, Openfabric
• Stefano Boeri, architect, co-director of the Wfuf scientific committee
• Cecil Konijnendijk, co-director of the Wfuf scientific committee
• Mattia Palazzi, mayor of Mantua

Cities consume 78 per cent of the world's energy

Although cities occupy only three per cent of the Earth's surface, they currently consume 78 per cent of the energy used across the entire world. And they are responsible for 70 per cent of greenhouse gas emissions. It is therefore precisely in this sphere that changes can be made capable of having a beneficial impact not only on the populations living in urban contexts but also in the global fight against climate change.

Starting from these premises, from 28 November to 1 December, the World Forum on Urban Forests (World Forum on Urban Forests) will convene in Mantua, bringing together representatives of national and local governments, research institutes and academics, non-governmental organisations, urban planners, urban foresters, arborists, landscape architects, designers and professionals from many other sectors. The objective: to exchange experiences, discuss possible long-term collaborations, and develop urban forestry strategies to plan a greener, healthier and happier future.

The Lombard city chose to host the forum as part of a broad strategy aimed at "urban and socio-economic renewal in the name of sustainability", as mayor Mattia Palazzi stated, above all through the multi-year project Mantova Hub, which aims to reclaim from decay precious areas in the eastern outskirts, currently unusable. In addition to the creation of areas dedicated to civic life and innovation — such as new squares and a research centre — the initiative also includes the planting of hundreds of native plants.

The World Forum on Urban Forests in Mantua

The event — promoted by the FAO — is organised with the support of the Municipality of Mantua, the Politecnico di Milano and the Sisef. Speakers from prestigious universities around the world will be in attendance. Among them, Harini Nagendra (India), Richard Weller (United States), Terry Hartig (Sweden) and Sylvie Nail (France). And the Italians Stefano Boeri (also , Francesco Ferrini and Giovanni Sanesi. "Wooded areas and trees — the United Nations emphasise — play numerous roles of great importance in cities and their outskirts. They absorb CO2, help to remove pollutants from the air, can be sources of food, improve energy and water security, make it possible to restore degraded soils and help to prevent droughts and floods".

The English city of Bath surrounded by trees. Urban forests are useful not only for the local environment, but also for mitigating climate change, ensuring health, wellbeing and territorial development © Matt Cardy/Getty Images

But that is not all: "By providing shade and cooling the air in urban areas, trees help to mitigate heatwaves and lessen the effects of climate change. If correctly positioned around buildings, they also reduce the need to use air conditioners by 30 per cent. Whereas in cold places, they protect homes from the wind and thus allow savings of between 20 and 50 per cent of the energy needed for heating".

From Beijing to Lima, the commitments of cities belonging to C40

The members of the C40 network, which includes 96 major cities around the world committed to defending the climate, are well aware of all this. They represent 25 per cent of global gross domestic product and one twelfth of the Earth's population. One of the metropolises belonging to the network is Beijing, which in 2012 launched the most significant reforestation programme in its history. In the areas immediately on the city's outskirts, the decision was taken to relocate numerous industries, with the aim of making room for new trees. In this way, the goal is to bring the urban green surface area up to 42 per cent of the total.

Trees in bloom in Bonn, Germany © Andreas Rentz/Getty Images

Similarly, the Kenyan capital Nairobi decided — thanks to pressure from local communities — to protect the nearby Karura Forest. Urban expansion had long since reached the woodland, which was being sacrificed to make way for property development schemes. Wangari Maathai, an environmentalist, had led a campaign to save the area. Thanks to a high level of community involvement and a strong awareness campaign, the environmentalists ultimately achieved their goal.

Meanwhile in Lima, Peru, the local authority decided to invest in the forest as an element capable of reducing the risks of natural disasters — in particular the landslides that can occur as a result of earthquakes. "The local population — the United Nations add — has understood that planting trees means reducing hazards, stabilising slopes, preventing rockfalls and limiting landslips." As a result, a 14-hectare park was created, in which 3,500 indigenous trees were planted, watered by means of a used-water treatment system. Footpaths and viewpoints have made it an attraction for residents and tourists alike — confirming that developing urban forests is a strategy with countless positive effects.