Book review of THE NATURE OF OUR CITIES

‍Editor’s note: This book review was originally written by Lieve Mertens and published in SamPol in January 2025. This version has been translated into English.‍

Children are naturally drawn to nature, yet they play outside less than their parents did. During the COVID-19 pandemic, we became more aware of our need for a connection with nature. It was during this time that Cecil Konijnendijk introduced the 3-30-300 rule for better mental well-being: having a view of three trees, 30% tree canopy coverage in one's neighborhood, and a park of at least one hectare within 300 meters of home.

Dutch-Canadian ecological engineer and author Nadina Galle speaks with people around the world who use technological innovation as a means to restore nature in our cities and our connection to it.

In the prologue, Galle paints a picture of a city without nature. It is evident that we need nature to protect us from heat and floods, but also for our mental well-being. Where we live has a major impact on our lifespan. Nature is a powerful tool against climate change and health problems.

Galle describes how nature is often sacrificed for economic interests. For example, in the late 1950s, the construction of a four-lane highway through Maastricht was celebrated as the beginning of a new mobility era. Residential blocks and trees were sacrificed, and while neighborhood social life declined, asthma rates increased. The highway attracted more traffic, and plans for expansion followed. However, after decades of activism, the plans were revised to build an underground tunnel instead. To build a truly smart city, we must prioritize a healthy environment. Now, the highway runs underground, with a local road and newly planted trees above.

However, these newly planted trees struggle during prolonged droughts. A sensor system that measures soil moisture could improve their survival rates. Galle discusses the Internet of Nature, where AI, machine learning, and other technologies help restore nature. There doesn’t have to be a conflict between technology and nature.

The Importance of Trees in Cities

‍Trees provide many ecological services: they absorb CO₂, purify the air, cool down hot days, and protect against flooding. Many people feel better around trees. However, urban trees do not always have ideal conditions, and the lifespan of a street tree is limited. A good urban tree management plan requires an inventory. This data can come from satellite images, LiDAR devices on cars and backpacks, or even volunteers mapping street trees. However, trees on private property remain outside these inventories, and in many cities, more trees disappear from private land than are planted in public spaces.

Urban Heat Islands and Solutions

‍On extremely hot days, cities suffer from the urban heat island effect, where temperatures are significantly higher than in surrounding rural areas, especially at night. The more paved surfaces there are, the more heat accumulates. Temperature differences within a city can be substantial: during the 2021 heat dome in Portland, temperatures in green neighborhoods reached 37°C, while in highly paved areas, they hit 51°C. The forecast for Portland was 45°C, but for some, it was much worse.

Drought, Wildfires, and Flooding‍

Prolonged drought increases the risk of wildfires. The Internet of Nature can help detect wildfires early, even at night. AI-powered image recognition can assist in preventing wildfires by identifying areas that need vegetation management under power lines.

There is a close link between heat domes, wildfires, and floods. After a wildfire, the loss of vegetation removes a crucial natural barrier against heavy rain, leading to floods. The best flood protection is natural solutions, such as widening rivers and restoring ecosystems. In urban areas, stormwater must be slowed down to prevent sewer overflows. Smart floodgates can be adjusted based on weather forecasts and water levels.

Biodiversity Loss and Citizen Science

‍Biodiversity loss is a growing concern, but it is difficult to track. Volunteers play a role in species inventories, while AI assists in identifying species. This sometimes leads to surprising discoveries, like species thought to be extinct. Once species presence is known, governments can implement necessary protections.

When more people participate in biodiversity tracking, public knowledge about nature increases and our relationship with nature improves.

Forest Bathing and the Healing Power of Nature

‍Forest therapy (or Shinrin-yoku) emerged in 1980s Japan, during rapid urbanization. Forest bathing helps people reconnect with themselves in a drastically changing landscape. Nature has a healing effect, and this understanding should play a role in urban green space policies.

Putting a Price on Nature’s Value

‍In a society where value is often measured in financial terms, it can be helpful to assign monetary value to nature’s ecosystem services. There are formulas to calculate the return on investment for green infrastructure.

To map nature, automated image recognition is applied to satellite images, including non-green natural features like rocks and rivers. This data can be combined with air quality and light pollution data to generate an urban nature score. A low score signals areas that would benefit from targeted green investments.

Encouraging Healthier Lifestyles Through Green Urban Planning

‍To improve public health, we must change our surroundings. Holding individuals responsible for unhealthy lifestyles doesn’t work. When neighborhoods have more green space and wide sidewalks, more people walk.

To encourage people to protect nature, they must first experience it. In urban areas, people spend most of their time indoors. Cities should be designed so that people live in green environments where children can play in nature.

Technology as a Tool for Connection, Not a Goal

‍Sometimes, technology can help reconnect people with nature, such as through games like World Safari or biodiversity challenges. We protect what we know.

Nadina Galle sees technological innovation as a tool to introduce more nature into cities and strengthen our relationship with it. However, technology should not be the ultimate goal, and caution is necessary.