Five important facts about urban forests

In the wake of dangerous heatwaves in Europe, Paris pledges to expand urban green spaces across the city. This blog post presents important findings from research and practice on the benefits of urban forests.

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urban forest in Barcelona
Barcelona, Spain seen through the trees in Park Güell. Photo: Sarah Feder.

Paris made headlines this week for a new project to build the largest urban farm in Europe, right in the heart of the French city. This urban farm is part of a broader urban greening trend in Paris, aligned with the city government’s ambitious goal to “green” 50% of urban surfaces by 2050.

In the wake of devastating heatwaves across Europe, with dangerous implications for human health in densely populated cities like Paris, these actions are particularly important. Urban areas can be as much as 8-12 degrees hotter than their more rural surroundings due to a phenomenon called “urban heat islands.” Urban forests, farms, and other urban green spaces have gained attention in global city planning efforts for their capacity to provide shade and to cool ambient temperatures through evapotranspiration.

However, the benefits of urban trees don’t stop there, and the impacts of urban forests may be more important than you think. This article presents five of the invaluable benefits urban forests provide, drawing on research and practice from experts at the European Forest Institute (EFI), and other leading scientists in the field.

1. Urban forests are “not a niche”

Although the global policy focus on the potential of urban forests is definitely increasing, a report published by the University of Copenhagen suggests that urban forests are not a new phenomenon, and are certainly not uncommon among European cities. Even in the 19th century, forested areas were integral to many cities; in fact, as urban areas in Europe have grown, fragments of previously rural areas have been absorbed into the urban green landscape.

The report presents a summary of results from a 2018 workshop on urban forests in Europe, supported by the European Forest Institute, that brought together leading practitioners and researchers to examine data gathered through the National Forest Inventory (NFI) “and identify its applications to nature-based solutions for urban societies”. Researchers concluded that in Europe’s most densely populated countries, almost 20% of forest area can be found in urban or peri-urban (natural areas or agricultural land that are adjacent to urban zones) areas, specifically within 2 km from cities. In Nordic countries, urban and peri-urban forests had nearly 180 times more forest visits than rural forests. These results, while highlighting the value that city forests can provide, also show that we are already benefiting from healthy urban forests across Europe.

malmo sweden forest
Autumnal woods just outside Malmö, Sweden.

2. Forests make people healthier

Urban forests provide key ecosystem services, like filtering air and water, that are essential to healthy human communities in cities where air pollution and water management can pose public health risks. Research has found that proximity to green space can be correlated with improved physical well-being, healthy lifestyles, and even psychological well-being. In a study carried out by the Forest Policy Research Network in Serbian cities, respondents perceived higher social benefits from activities carried out in a green space. According to the study’s results, green areas may even have the potential to replace medication use for certain psychological problems. Research like this is central to a pilot project led by Mireia Pecurul-Botines, of the Forest Science Centre of Catalonia (CTFC), which aims to incorporate forests into holistic health and well-being programmes with a local school in Solsona, Spain. The project, which focuses on the intangible benefits of simply spending time in a forest environment, also sheds light on the importance of forests in building social networks and strengthening community efforts to protect and promote forest resources.

urban park in London
City residents enjoy a sunny day in an urban park in London, UK.

3. Urban forests promote environmental education

Urban areas are at the center of many global changes: urban sprawl stretches into forest and agricultural lands; young people are drawn to cities; and urbanisation places increasing pressure on rural ecosystems that are weakened by fragmentation, abandonment, and climate change.

As Marco Marchetti and his co-authors elaborate in their paper, Natural capital and bioeconomy: challenges and opportunities for forestry, the relationship between rural and urban areas, while it can be fraught, is crucial to strengthen resilience in both landscapes. The bioeconomy concept has been embraced as a holistic, long-term solution to revitalise rural areas while continuing to provide for human needs in Europe and beyond. Synergies within the urban-rural relationship are central to the success of such bioeconomy policies and practice. Marchetti et. al suggest that to maintain the identity and support the role of rural landscapes, urban populations holding political and economic power must recognise the importance of the countryside both as a producer of food and energy, and also as the site of healthy, high-quality lifestyles. “Green infrastructures can contribute to these goals,” the paper highlights, by connecting people to natural and semi-natural areas, and thus facilitating awareness and understanding between rural and urban populations.

Rock Creek Park, one of the first national parks in the US, in Washington, DC. Photo: Christopher Arderne.

4. Money grows on trees

From an urban planning perspective, trees provide quite a bang for their bark. In contrast to expansive forest landscapes, in a city, small groupings or even individual trees can provide measurable economic, environmental, social, and health benefits for urban populations. According to this video from EFI, planting trees near buildings can cut air conditioning use by 30% and reduce heating use by 20-50%. When tree-planting is integrated into urban and landscape planning across an urban area, trees can cool cities between 2-8 degrees – a particularly salient function as heatwaves in Europe will likely intensify in the coming years. These services, among many others, contribute to lowering yearly costs for cities, and for individual citizens. This video from the Halifax Regional Municipality in Canada shows how their urban planning department harnesses the many benefits – including financial – that trees can provide to urban residents.

Urban and peri-urban forests can also provide financial benefits to cities by helping to alleviate social burdens and barriers: the SocialForest team uses vocational training in forest management to help integrate at-risk youth in Spain, and my own research on urban heat suggests that the fair distribution and quality of green spaces in a city can be linked to social equity.

antwerp city street
Trees line a city street in Antwerp, Belgium.

5. Urban forests are essential in the face of climate change

A city’s resilience to climate change can be understood both by its ability to adapt to changes, and its capacity to help mitigate their impacts. As political entities, urban planners, and rural land managers are working to develop “nature-based solutions” to improve climate resilience across regions, urban forests have taken a leading role for their many functions and benefits within urban landscapes. Like all forests, urban forests can play a role in storing carbon. One study based on national urban tree cover data and field data from U.S. cities estimated that urban forests in the U.S. currently store over 600 million tonnes of carbon. Additionally, the urban forests under study had faster rates of carbon sequestration than other forests, storing nearly three times as much carbon per year as protected national forests in the Pacific Northwest.

Trees can also help urban communities adapt to threats that are exacerbated by climate change: providing shade and lowering ambient temperatures during heatwaves; reducing flood risk in the case of extreme weather events; and even limiting the development of ground-level ozone, which can lead to toxic air pollution. These inspiring stories of climate resilient cities from FAO Forestry show how strengthening and expanding our urban forests not only enhances the resilience of cities in the face of climate change, but also demonstrates how we as humans can adapt and respond to our changing environment.

Craving more urban forestry facts?

In addition to the references provided throughout this article, you can find out more by exploring the urban forestry tag on MedForest, by visiting the Resilience Programme page on EFI’s website, or by looking through abstracts from the 2019 European Forum on Urban Forestry, which is supported by EFI.