The power of nature in cities: new solutions for adapting cities to climate change

Climate change is already causing increasingly higher temperatures and heavier rainfall in Slovenian cities and towns, creating less healthy and safe living environments for people, animals, and plants. Natural elements and processes in plants and soil play a crucial role in mitigating the effects of climate change. This requires action by municipalities. In urban areas, this has led to nature preservation efforts and management of green spaces. New principles and concepts like green and blue-green infrastructure and nature-based solutions are gaining traction.

This was the focus of the international conference The Power of Nature in Cities, organized by the Ministry of Natural Resources and Spatial Planning, IPoP – Institute for Spatial Policies, and the Association of Municipalities and Towns of Slovenia on 12 November 2024 in Ljubljana. Over 160 participants had the opportunity to explore best practices and develop ideas for solutions suitable for Slovenian urban areas and municipalities with the help of international examples.

In Slovenia, the unique characteristics of urban areas and relatively preserved natural environments create a misleading impression that nature and its benefits are omnipresent and always nearby. As a result, managing green spaces and greening urban areas might seem less urgent, but this is not the case. In Slovenian urban areas, people also need upgraded green spaces and greener public spaces to better cope with high heat and heavy rainfall. Slovenian municipalities are already adapting their green spaces and planning new ones with support from the Ministry of Natural Resources and Spatial Planning.

The audience was reminded of these issues by the Minister for Natural Resources and Spatial Planning, Jože Novak, who emphasized that climate change and its consequences are happening faster and becoming more evident. He highlighted the crucial role of spatial planning in mitigating the impacts and strengthening the resilience of urban areas. Spatial planning must now, more than ever, aim for coordinated, deliberate, and rational use of space. The ministry supports climate change adaptation through regulations, as well as the preparation of strategic documents, guidelines, principles, and recommendations. Additionally, they provide financial support to municipalities for improving existing green spaces and greening new areas through the European Cohesion Policy.

The practice of ambitious greening and urban adaptation to climate change was further explored by Professor Cecil Konijnendijk. Known for the persuasive and practical 3-30-300 concept developed during the pandemic, he is currently one of the most prominent advisors and advocates for the role of trees and green spaces in climate resilience and public health, as well as the co-founder of the Nature-Based Solutions Institute. Among other points, he stressed that trees are the foundation of living environments and that protecting mature trees and ensuring favorable conditions for their longevity is of utmost importance. He highlighted the benefits urban trees (3), tree stands (300), and street trees (30) bring to the environment and well-being. He particularly emphasized the significance of proximity to trees for well-being and health, drawing attention to the role of “doorstep trees”, to which people have a uniquely personal and emotional connection. He reminded us of the environmental, societal, and economic impacts of New York’s Central Park and the concept of the “sponge city”. In both cases, trees and the processes occurring within them play a key role in delivering positive environmental outcomes.

Professor Konijnendijk underlined the importance of connecting residents and local communities with nature and referenced EU documents that advocate for preserving nature, particularly mature trees. He inspired us with practical examples and encouraged us to think about effective actions within our own local environments. He recommended four types of interventions he found most effective for adapting to climate change and ensuring public health and well-being: (1) increasing urban canopy cover, (2) establishing pocket parks in every neighborhood, (3) creating opportunities for social interactions in areas, such as community gardens, and (4) greening schoolyards and their surroundings.

Research underlying Konijnendijk’s approach to action demonstrates that simply having a view of trees and natural elements through the windows of one’s home significantly contributes to well-being and improved mental health. Moreover, sufficient canopy cover in urban environments can critically impact air temperature, thereby influencing heat-related health effects and reducing premature mortality. During the pandemic, Konijnendijk connected these findings with established recommendations from the World Health Organization, which emphasize the importance of having residential areas no more than 300 meters away from well-maintained green spaces for health and well-being. This led to the development of the 3-30-300 rule, which states:

• Every person should have a view of at least three large trees from their home or other spaces where they spend significant time (e.g., nursing homes, hospital rooms, classrooms, offices).
• Each neighborhood should have at least 30% tree canopy cover.
• Everyone should have access to a well-maintained green space large enough for recreation and recovery within 300 meters of their doorstep.

This rule has already been adopted as a framework for planning actions in many cities worldwide, including most Dutch cities. The Dutch government itself conducted a baseline analysis of tree canopy coverage for all cities in the country and established a unified inventory system for all urban trees.

Konijnendijk emphasized the importance of policymakers understanding the effects of actions proposed by experts. He advised beginning consultations with municipalities and cities with a walk through the streets alongside local policymakers, similar to his own practice. He remarked: “Sometimes you need to feel the positive effect of trees—take the politician for a walk, first along a nicely shaded street with trees and then along a sunny street.” Such an experience can fundamentally change the conversation about the importance of preserving trees, thoughtfully planting new ones, and developing and greening public spaces.

The lecture was followed by Professor Lilli Lička from the Institute of Landscape Architecture at BOKU University in Vienna, who is internationally recognized for her proactive approach to implementing theoretical principles and research findings in practice. Currently, along with over 20,000 supporters, she is advocating for the preservation of one of Vienna’s green corridors along the railway line, connecting the Vienna’s woods on the outskirts to the city center (Westbahnpark). This year, she was also the keynote speaker at the World Urban Parks Congress 2024 in Utrecht.

Lička added a social dimension to the discussions on the importance of preserving nature in urban areas and greening cities, highlighting her perspectives through various examples from Vienna. She spoke about the intersection of climate and social justice, as reflected in green spaces, the residents’ access to them, and their distribution. She began by referencing Jane Jacobs and her advocacy for public and street spaces, adding that today, the renowned urbanist would undoubtedly agree that public spaces are essential for quality living, social equity, and community cohesion.

Even in Vienna, often regarded as a green city with over 50% of its area covered by green spaces, these spaces are unevenly distributed. The majority of green areas are on the outskirts, while densely populated neighborhoods and the city center have significantly less green. Vienna’s continental location makes it particularly prone to overheating, with some urban areas becoming excessively hot during summer—a problem that is becoming increasingly severe each season and poses life-threatening risks for some residents.

Professor Lička highlighted the stark differences between new and older parts of the city. She noted that planning new green spaces is much easier in the new neighborhoods emerging across Vienna, as the city’s population grows by 20,000 to 25,000 every year. In contrast, in existing urban areas and already developed neighborhoods, high building density leaves little room for new green spaces. For these areas, the only viable solutions are small pocket parks and repurposing streets, roadways, and even parking spaces into temporary and permanent green oases.

She mentioned the creation of parklets as part of the Grätzloase program, where local residents propose greening and other projects and take responsibility for maintaining these spaces, which allow for outdoor living and socializing. Lička also revealed that Vienna has set an ambitious goal in its strategic development plans: ensuring that all residents have access to green spaces within 250 meters of their homes, an even closer range than the 300-meter recommendation by the World Health Organization.

“Public spaces are the vital organs in cities.”

Professor Lička emphasized the microclimatic role of green spaces and the importance of preserving so-called green corridors, which not only sustain biodiversity but also enable cooler air from the outskirts to flow towards the city center. One such corridor in Vienna is an abandoned railway line around which, in recent years, various development interests and ideas for construction have sparked a movement advocating for the creation of a new park—Westbahnpark.

Lička has been actively involved in this initiative through objective explanations, proposals, and even activist actions, strongly emphasizing the importance of preserving this corridor for the quality of life of local residents and better microclimate of the city. Meanwhile, city authorities are planning construction in the area but are attempting to address residents’ needs for green spaces by greening rooftops on new buildings. These measures, however, fall short against the full benefits of the greenbelt preserved along the railway embankment. “At some point, you have no choice but to become an activist,” Professor Lička summarized the situation regarding this case.

In the second part of the conference, we heard inspiring stories from various European cities that have implemented new and innovative practices for urban greening and green space management.

The first speaker was landscape architect Martí Franch Batllori, founder of the EMF Landscape Architecture studio. He seamlessly built upon the preceding presentations by sharing the story of landscape management in the peri-urban green areas of the Catalonian city of Girona. Their innovative approach represents a new practice in landscape maintenance, functioning as a process of creating space and green infrastructure. It draws inspiration from nature-based solutions and the work of French botanist and public garden and park designer Gilles Clément.

At the center is a strategy to activate Girona’s extensive natural outskirts for everyday leisure use, enhanced quality of life, increased urban appeal, and improved fire safety. Before the project began, the area was an overgrown, underutilized space. Over two years, Martí Franch and his team, together with municipal technical teams and green space maintenance workers, thoroughly explored the area, assessed its conditions, and designed a maintenance plan. This plan not only focused on creating an engaging environment for daily walks, regeneration, and recreation but also incorporated tailored maintenance strategies such as mowing and pruning, adjusted to plant types, site conditions, and usage frequency.

Without any significant additional funding, the city leveraged a creative approach to activate new green spaces for public use. This effort also initiated a shift in how both municipal authorities and residents perceive green spaces and their maintenance. The impact of this new method has highlighted the untapped potential of landscape management for existing green spaces. It has also proven to be economically efficient, with an average cost of just €1–2 per square meter for the new maintenance approach.

»Updated public systems like software. We need to update our cities.«

By introducing creative planning into maintenance processes, it is possible to enhance the culture of space management while also achieving broader development goals, such as preserving biodiversity and improving fire safety. Through collaboration and education, Girona has gained a wealth of new local knowledge in just two years. Thoughtfully designed activities for residents—such as walks, concerts, and art installations—have brought communities closer to the new green spaces. Public communication and awareness efforts are gradually transforming entrenched perceptions of aesthetics, promoting the acceptance of differently managed and functional green areas that enhance biodiversity and strengthen natural processes.

“We should all be a little bit more ‘punk’ when it comes to city greening.”

The collaboration between the landscape architecture office and the city initially began as a two-year pilot project. It has now evolved into a more stable partnership through a contract resembling those of public utility companies. This agreement ensures more sustainable collaboration, planning, and funding for new developments in other areas. Discussions are also underway to establish even more long-term cooperation with municipal services, with aspirations to follow France’s successful model, where such long-term partnerships are already well-established.

The next speaker was Tomas Stoisser from the Department of Green Spaces and Water Management in the City of Graz. He brought the discussion closer to practical urban realities by presenting the city’s current practices in urban tree planting and maintenance, as well as the implementation of the sponge city principle in Graz, Austria. In a city of approximately 300,000 residents, the administration manages about 26,000 urban trees, a number that is rapidly increasing.

Faced with challenges like heatwaves and heavy rainfall, the city and its residents expect more from their urban trees. Initial analysis revealed that one-third of the existing trees were in poor condition and would need replacement in the near future. Currently, the city replaces about 300 of these trees annually and plants an additional 500 new ones. For planting trees in urban squares and streets, Graz employs the Stockholm approach, which focuses on meeting the growth needs of trees in challenging urban environments. This method involves planting trees in specially designed substrates. Combined with measures to minimize root pressure, this approach creates favorable conditions for trees planted in paved areas. The city also uses traditional planting methods and consistently compares the results of the two approaches.

“We need big trees with big canopies in dense urban areas.”

In line with the sponge city concept, Graz aims to enhance rainwater retention on-site by introducing clusters of trees or “green islands” into the urban space. Group planting in shared, interconnected planting pits forms a type of point-based green-blue infrastructure that is significantly more effective in providing ecosystem services than planting individual trees. Consequently, the city strives to incorporate as many tree groups as possible into urban spaces. These groups, along with permeable and well-configured planting environments and undergrowth, help retain rainfall, cool the environment, and improve the aesthetics and experience of urban areas.

Additionally, during street renovations and modifications to paved and traffic-dense surfaces, Graz ensures that rainwater is retained on-site and that any excess water is redirected to the trees and their planting areas. They further enhance rainwater retention by adding biochar to the planting substrate, which initially absorbs water and then gradually releases it as needed by trees and other plants. Gravel is also added to improve water infiltration into the groundwater. The city actively experiments with new planting techniques and closely monitors their effects, continually refining both planting methods and the selection of tree species and seedling quality to better match the conditions and locations of the planting sites.

We concluded the stories from European cities with a presentation by Ferenc Albert Szigeti, URBACT expert of the BiodiverCity network and founder of TeAM HUB, a hub for nature-based solutions in Hungary. He guided us through practices aimed at preserving and enhancing biodiversity in Hungarian cities. 

In Hungary, they among others face the challenge of conserving wild grasslands (steppe), which are characteristic of their climate and environment but are not widely recognized by communities as valuable spaces or ecosystems. In Veszprém, they addressed this mindset by establishing wild grasslands in neighborhoods, where only the edges of these areas are mowed more frequently, and the spaces are equipped with information boards. They quickly realized that this approach also led to cost savings in the maintenance of green spaces.

In Budapest, they transformed green spaces in ways that strengthened biodiversity. A new park now features a mosaic of different habitats, including wetlands and other water elements such as rain gardens. These are interwoven with grasslands with special mixtures of flowering grasses and other honey-bearing plants, along with perennial plantings. The area also includes shelters for wildlife and fruit trees to enhance biodiversity.

“Nature is an ally in the climate change combat.”

In the Budapest district of Hegyvidék, they initiated a pilot project involving the planting of young, locally adapted tree species sourced from nearby forests, which are more likely to thrive under new conditions. The pilot project is part of a community program through which residents can request free tree pruning, compost bins, rainwater collectors, and seedlings, as well as participate in the establishment of community gardens. The program includes educational and awareness-raising activities, such as “Climate-Friendly Evenings,” and provides detailed guidelines for planting, composting, and more on its website.

The concluding part of the conference focused on finding solutions for adapting Slovenian towns and cities to climate change through greening initiatives. The discussion brought together representatives from the national government, association of city municipalities, municipality, utility company in charge of public green spaces and experts on public green spaces.

• Dr. Nataša Bratina (Ministry of Natural Resources and Spatial Planning) highlighted Slovenia’s delay in climate adaptation and drew attention to the EU’s requirement to ensure 40% open green spaces in urban areas. She announced new professional guidelines and accelerated measures at the national level. She also emphasized the success of the cohesion fund call for greening, which received 130 municipal applications.
• Miran Košpenda (Association of City Municipalities of Slovenia) discussed the collaboration within the Urban Agenda EU Partnership for urban greening, particularly in a working group focused on securing financial resources. He suggested that the Slovenian Climate Fund could serve as a significant funding source for greening projects, as current cohesion funds are not predictable in the long run.
• Valentina Glinšek (City Municipality of Celje) presented their strategic measures for preserving nature in urban areas, such as a tree maintenance plan and the management of an urban forest. The municipality received the URBACT Good Practice recognition for its sustainable forest management efforts.
• Jože Krulec (Public Utility Company ZELENICE) described the work of Celje’s utility company, which manages 104 hectares of public green spaces. The company is introducing modern practices and preparing a tree registry but faces challenges such as a lack of skilled personnel and local nurseries.
• Urška Kranjc (LUZ d.d.) highlighted the importance of an interdisciplinary approach to designing new developments, combining technical and landscape solutions. She stressed the need for better training among contractors and the importance of effective communication with the public regarding changes, such as tree removal and new plantings.

Maja Simoneti, the moderator of the roundtable, concluded the conference by emphasizing that in urban and other settlements, every tree and green space matters and brings benefits. This applies both to those that must be preserved and to those that are thoughtfully integrated into the urban environment. She reminded us that by caring for ourselves and the effects of climate change, we are also nurturing biodiversity and strengthening the power of nature in cities.

Galerija fotografij

Avtorica: Tea Stepan

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Conference is organised by the Ministry for natural resources and spatial planning, IPoP – Institute for Spatial Policies and Association of Municipalities and towns of Slovenia as part of the project Supporting the implementation of spatial and urban policy. The event organised with support of URBACT and European Urban Initiative.