In an era of rapid urbanization, where over 56% of the world’s population lives in cities—and this figure is projected to rise—innovative approaches are emerging to reconnect urban environments with nature. Vertical forests and urban rewilding represent two complementary strategies that bring greenery, wildlife, and ecological processes back into densely built areas, fostering biodiversity while enhancing human well-being.
What Are Vertical Forests?
Vertical forests are high-rise buildings designed with extensive vegetation integrated into their facades, balconies, and terraces. Pioneered by Italian architect Stefano Boeri, the concept transforms skyscrapers into living ecosystems.
The iconic Bosco Verticale (Vertical Forest) in Milan, completed in 2014, features two residential towers hosting over 900 trees, 5,000 shrubs, and 15,000 perennial plants—equivalent to a hectare of traditional forest on a minimal urban footprint.
These structures use advanced irrigation systems (often recycling graywater) and careful plant selection to ensure sustainability.
Benefits include:
- Absorbing CO₂ (up to 25-30 tons annually per project) and producing oxygen.
- Reducing urban heat islands by cooling surroundings.
- Filtering fine particles and noise pollution.
- Boosting biodiversity: Milan’s Bosco Verticale has attracted over 1,600 bird and insect species, creating habitats in concrete-dominated areas.
Similar projects now exist in Nanjing (China), Eindhoven (Netherlands), and beyond, proving the model’s scalability.
Urban Rewilding: Letting Nature Reclaim Cities
Urban rewilding goes beyond manicured parks by restoring natural processes in city spaces—allowing native vegetation to grow freely, reintroducing wildlife, and reducing human intervention. It transforms underused lots, rooftops, roadsides, and industrial sites into self-sustaining ecosystems.
Examples include:
- New York’s High Line, an elevated park on abandoned rail tracks teeming with native plants and pollinators.
- Reduced mowing in Dublin’s parks to encourage wildflowers and insects.
- Pocket forests in cities worldwide, creating dense native habitats.
Rewilding enhances resilience against climate change, improves mental health through nature access, and supports pollinators vital for food systems.
How They Integrate: A Synergy for Thriving Urban Biodiversity
Vertical forests and rewilding overlap and complement each other. Vertical forests act as “vertical rewilding,” providing elevated habitats that connect to ground-level green corridors. Together, they create networks of biodiversity hotspots, mitigating habitat fragmentation in cities.
In Milan, the Bosco Verticale is often cited in urban rewilding discussions as a model for “renaturalizing” built environments. Scaling these approaches—through policies like Melbourne’s Urban Forest Strategy aiming for 40% canopy cover—can reverse biodiversity loss, where urban areas often see sharper declines than rural ones.
Challenges remain: high maintenance costs for vertical forests, potential conflicts with non-native species in rewilding, and the need for community buy-in. Yet, evidence shows these strategies improve air quality, lower temperatures by 2-4°C, and foster resilient ecosystems.
As cities grow, embracing vertical forests and rewilding isn’t just aesthetic—it’s essential for sustainable urban life where humans and nature thrive together. Projects worldwide demonstrate that even dense metropolises can become biodiverse havens.