Earth Day: Open Your Eyes to Biodiversity

First celebrated in 1970, Earth Day now mobilizes more than a billion people each year in nearly 190 countries. This day serves as a reminder of the urgent need to take action on environmental issues and encourages concrete steps to protect the planet.

To Protect Biodiversity: Let’s Open Our Eyes

In 2025, Earth Day Canada‘s campaign invites citizens to “open their eyes” to protect biodiversity. Observe, understand, act: that is the heart of this invitation. It’s about learning to see the richness of life around us, recognizing the role of species, becoming aware of the threats they face… and taking concrete action to protect them.

Connecting Natural Environments, One Garden at a Time

Planting a native perennial, leaving a corner of the garden untended, sowing flowers for pollinators, avoiding pesticides… These individual actions, however modest, can transform our living environments. Repeated from one garden to another, they create ecological continuity across our communities. And little by little, passages for wildlife emerge.

An ecological corridor is a green path that connects separate natural environments. It allows animals and plants to move, feed, reproduce, or change habitats, particularly in response to seasonal or climate change. These corridors can be woodlands, rivers, parks… or even urban gardens.

In urban areas, natural environments are often fragmented by roads and other structures. However, with careful planning, cities can contribute to ecological connectivity. Well-located parks, vegetated strips, or even cemeteries and road embankments can serve as passages for wildlife.

When large green spaces are lacking, small private gardens can fill the gap. These “stepping stones” allow insects, birds, and small mammals to move from one habitat to another.

Every green space, large or small, counts. By connecting them, we can create a living ecological network that benefits both nature and city dwellers.

Gardens as Genetic Corridors

But gardens do more than just connect environments: they can also strengthen the bonds within species themselves. In addition to serving as physical passageways, they facilitate genetic exchange between animal populations, particularly among pollinating insects.

This was demonstrated in a study conducted in California by Jha and Kremen (2013). The researchers observed that increasing floral diversity in urban gardens, combined with a reduction in impervious surfaces such as asphalt, allowed bumblebees (Bombus vosnesenskii) to move more easily between urban and rural environments. This type of movement promotes what is known as gene flow—the exchange of genes between different populations—which enriches genetic diversity. A more diverse population is better equipped to cope with disease, climate change, and other disturbances. Gene flow thus strengthens the resilience of species and their ability to adapt to a constantly changing environment.

So even on a small scale, a garden can contribute to the ecological connectivity of an area.

Essential Havens for Biodiversity

Urban green spaces, particularly community and residential gardens, can also play a crucial role as refuges for declining species, thereby contributing to regional biodiversity conservation. Far from being mere decorative feature, these environments sometimes become valuable reservoirs of biodiversity.

For example, a study conducted in New York shows that community gardens are home to a wide variety of bees, including several native species, some of which are rare or sensitive to habitat loss. Their density and frequency of observation are sometimes comparable to, or even higher than, those measured in certain peripheral natural environments.

In Toronto, a citizen science project led by the University of Toronto has identified more than 360 species of bees in the city, one of the greatest urban diversities recorded in North America. These data show that, when well designed and maintained, urban green spaces can support rich and functional biodiversity.

This role as a refuge is all the more essential in a context where natural environments are increasingly fragmented or transformed. Urban green spaces, including private gardens, play a crucial role in safeguarding biodiversity on a larger scale by acting as true ecological sanctuaries in the heart of disrupted landscapes.

Factors Influencing Biodiversity in Urban Areas

At first glance, cities may seem unwelcoming to nature. However, between sidewalks and walls, there is still space for life to take root. Gardens, balconies, and even alleys can provide a foothold for biodiversity. But it all depends on how these spaces are designed.

Native plants are particularly valuable to local wildlife because they have evolved together over time. Many herbivorous insects, such as butterfly caterpillars, depend on specific plant species for food. In turn, these insects feed birds, amphibians, and other predators, supporting an entire food chain. Incorporating native plants into landscaping therefore helps strengthen this ecological network.

The larger a garden is, the more species it can accommodate. Size directly influences the diversity of habitats available and the quantity of resources on offer. A review published in Biodiversity and Conservation showed that species richness in urban gardens is often correlated with their size. This does not mean that small gardens are useless, but it does highlight the importance of preserving, connecting, or expanding green spaces whenever possible.

A garden consisting solely of lawn offers little shelter and food. On the other hand, a garden structured with several layers of vegetation—trees, shrubs, perennials, ground cover—creates a diversity of microhabitats. This complexity attracts different species, depending on their needs, from the ground to the foliage. Even the presence of a woodpile, a patch of fallow land, or an open hedge can multiply the possibilities for urban wildlife.

Connect to Protect: An Inspiring Example

In Seattle, an original project has demonstrated that even in the heart of the city, citizens can play a direct role in creating functional ecological corridors. Launched in 2008 by artist and designer Sarah Bergmann, the Pollinator Pathway aimed to connect two large urban green spaces one kilometer apart, passing through a residential street. The concept was to transform front yards and small green spaces into gardens for pollinators, planted with native species.

The project relies entirely on collaboration between homeowners, volunteers, landscape architects, students, community organizations, and universities. Together, they designed, planted, and maintained these microhabitats, which now form an ecological corridor in the middle of the city. Today, about 20 of them are still actively maintained, and together they are home to more than 1,000 native plants.

The results were concrete: field surveys observed a clear increase in the presence of solitary bees, hoverflies (pollinating flies), and butterflies in the transformed areas. The project also inspired similar initiatives in other cities, demonstrating that an ecological corridor could emerge from a series of small, coordinated actions at the neighborhood level and that there was potential for collaboration between residents, volunteers, and local institutions to promote biodiversity in urban areas.

Earth Day: The Power of Community

Earth Day reminds us of the power of collective action. From citizen marches to neighborhood mobilizations, group actions are pushing for change in our societies. But these efforts are fueled by our individual, concrete, everyday actions. A flower-filled meadow for pollinators, a shared vegetable garden, a hedge of native plants: each of these actions, repeated and multiplied, becomes part of a larger change.

Want to transform your garden into a haven for biodiversity? Whether you have a large yard, an urban courtyard, or just a balcony, every action counts. Space for Life’s “My Space for Life Garden” program offers resources to guide you in designing a garden that is friendly to pollinators, birds, and local wildlife. In addition to recognizing your efforts with official certification, the site offers a wealth of practical information for creating diverse designs tailored to your situation.

For more information on Earth Day activities, visit Earth Day Canada or EARTHDAY.ORG.