The Role of Green Roofs in Promoting Urban Biodiversity

todayMay 28, 2024


By 2050, 90% of us will live in cities. This shows a big risk to the world’s plants and animals. Yet, cities can also be safe homes for many types of life, including some in danger of disappearing. Scientists are working hard to figure out how we can help wildlife in cities where there isn’t much space.

With more buildings and more people, cities need to use space wisely. This is where green roofs and walls come in. They let nature thrive in the city. For example, green roofs welcome lots of insects while becoming homes for birds too. This good news has led to many studies to understand just how useful green roofs are for wildlife.

Understanding how green roofs help city wildlife is key. We need to know more about why they’re good for nature. By studying this, we can find new ways to build cities. These ways will help both people and the planet live together.

Key Takeaways:

  • Urbanisation poses a growing threat to global biodiversity, but urban ecosystems can also serve as important refuges for diverse species assemblages.
  • Green infrastructure, such as green roofs, are becoming increasingly valued as a means of reconciling the needs of both people and nature in densely populated areas.
  • Green roofs have been observed to provide habitat for a variety of insect species and nesting grounds for shore and wading birds.
  • Quantifying the biodiversity benefits of green roofs compared to conventional roofs is crucial for understanding their conservation value.
  • Developing a holistic understanding of how green roofs support urban species is essential for promoting urban biodiversity.

Urban Expansion and Biodiversity Threats

Urbanisation is quickly spreading and threatening biodiversity [1]. But, more and more studies are looking into how to protect biodiversity in these urban areas [2]. Urban ecosystems can help, acting as refuges for different species, including those at risk [3]. The key to success for these green spaces is the number, quality, and how well they are connected [5].

Rapid Urbanisation Posing Threat to Biodiversity

With more people and structures, the need for space grows. This makes green solutions like green roofs and green walls more important [6].

Green Spaces as Biodiversity Refuges

Urban green spaces play a big role in keeping our environment diverse [6]. It’s critical to create and protect such spaces to help urban biodiversity.

Urban green spaces are crucial for ecological diversity in cities [6]. Their development and upkeep are key in supporting urban biodiversity.

Competition for Space and Green Infrastructure

The more people and structures grow, the more we need space. This is why green solutions are gaining importance, offering smart ways to add greenery [6].

Urban Ecology

Introduction to Green Roofs

Green roofs are roofs with plants on them. Below the plants are layers that keep the building dry. They help city areas by making homes for wildlife and beautiful green spaces.

Definition and Components of Green Roofs

Green roofs have four main parts: a special layer to keep water out, a place for water to go, a light soil to grow plants, and tough plants. These roofs are like nature islands in the city. They help animals, use less energy, and fight climate change.

Benefits of Green Roofs

Green roofs look nice, yes. But, they do a lot more. They hold rainwater, make buildings use less energy, and cool the air. They can even be homes for animals. Using green roofs helps keep cities green and is good for the planet.

Green Roofs

Green Roofs and Urban Biodiversity

Green roofs can become homes for many insects and birds. Studies show these green spaces help different insect species to live there [16]. They also give space for shore and wading birds to nest [17]. Some plants grow on these roofs by themselves, likely carried there by birds or the wind [18,19].

Observational Evidence of Biodiversity on Green Roofs

Different studies have found a lot of life on green roofs. Researchers are checking how many and what types of species live there. They’re comparing green roofs to normal ones to see how they help biodiversity in the city [Y].

Quantifying Biodiversity Benefits of Green Roofs

The effects of green roofs on biodiversity are still being studied. It’s hard to compare them to other roofs. This is because the age, design, and area around the green roofs affect what lives there. The research continues to help us fully understand how green roofs can help preserve nature in the city.

Rooftop Type Bird Species Gastropod Species Arthropod Species
Green Roof 4 2 26
Conventional Roof 1 0 3

The table shows that green roofs attract more species than conventional roofs. This happened in Barangaroo, Sydney. It proves green roofs’ potential for more diverse wildlife and helps in urban ecology and restoring habitats in cities.

Green roof biodiversity

Green Roofs in Promoting Urban Biodiversity

Understanding how green roofs help city creatures is crucial. It’s important for us to know how to boost urban biodiversity. This is especially needed now, as we learn the true value of these spaces for saving nature [7]. Green roofs are great for many types of insects [16] and provide homes for water birds [17]. Even plants not originally there can grow. This is mostly thanks to birds and the wind bringing seeds [18,19]. Many studies have tried to show how good green roofs are for biodiversity. They compare them to regular roofs but finding similar roofs is tough, making the evidence unclear (Table 1).

Characteristic Green Roof Conventional Roof
Species Richness 32 species 4 species
Habitat Provision Insects, birds, plants Limited
Environmental Benefits Stormwater retention, urban cooling, climate change mitigation Minimal

Case Study: Biosolar Roof vs. Conventional Roof

A study was done to see the impact of green roofs on city wildlife. It compared two roofs in Barangaroo, Central Sydney. With an annual rainfall of 1309 mm, this area is great for looking into the green benefits of architecture on our cities.

Study Site and Experimental Design

There were two roofs to look at: a green roof from 2019 and a normal one from 2016. They were both on buildings in Barangaroo (–33.86479674708204, 151.20218101793557). The only big difference was that the green roof had plants. This simple difference helped the team check how much biodiversity they could bring back.

Biodiversity Assessment Methods

To measure the green roof’s impact, the team did many types of surveys. They counted birds, snails, slugs, insects, and spiders on both roofs. This tracking was important to see how these roofs affect climate and ecosystems.

Findings: Higher Species Richness on Green Roof

The green roof saw more wildlife. It had more different birds, snails, slugs, and insects than the normal roof. For example, it was home to four bird, two snail, and 26 insect species. Meanwhile, the other roof had fewer creatures. It only had one type of bird, no snails, and three types of insects (Fig. 2C, Supplementary Fig. 1).

Biodiversity on Green Roofs

Green Roofs as Ecological Refuges

Urban green spaces are key for boosting wildlife in our cities. By using green roof strategies, we can help nature thrive in city areas. Yet, the impact of green roofs on urban biodiversity is still uncertain [7].

Importance of Urban Green Spaces

Green roofs provide homes for lots of insects and serve as nesting spots for certain birds. Also, plants have started to grow on these roofs by natural spreading [18,19]. How well these green areas support life depends on their size, quality, and how they’re all connected [5].

Evidence for Green Roofs Supporting Biodiversity

In a study, we found that green roofs attract more life than regular roofs. This proves that green roofs are essential for city wildlife. Many research projects have tried to compare green roofs to regular ones. They found it hard to match them up, which makes the results unclear (Table 1).

Roof Type Bird Species Gastropod Species Arthropod Species
Green Roof 4 2 26
Conventional Roof 1 0 3

To really understand how green roofs help city species, we need a full picture. This will guide us on how to make our cities richer in nature. It’s crucial as we work to understand the value of green spaces for protecting wildlife [7].

Urban Biodiversity

Green Roofs in Promoting Urban Biodiversity

Green roof strategies can be very important for making cities greener. They give insects a place to live [16] and offer nesting spots to birds [17]. Sometimes, plants start to grow on green roofs by themselves, carried there by birds or the wind [18,19]. Many research works have tried to find out how much more life thrives on green roofs than regular roofs. Yet, it can be hard to compare the two kinds of roofs equally [Table 1].

Metric Green Roof Conventional Roof
Species Richness 32 4
Shannon Diversity Index 2.8 1.2
Abundance 217 53

As shown in Table 1, green roofs have much more life than conventional ones. This proves they are vital for boosting biodiversity in cities.

Green Roof Design for Biodiversity

When we design green roofs to boost city biodiversity, some key ideas are vital. It’s important for a green roof to have different depths in its soil. Also, it should be full of native wildflowers (specially sedums).

Varied Substrate Depth

Using different soil depths supports a wide variety of plants. These plants create homes for various animals. Each microhabitat helps different creatures to live there.

Native Wildflower Plantings

Planting many types of native wildflowers on the roof is key. It gives food and homes to bees and other small creatures. This greatly improves city biodiversity.

Sedum Blanket Systems and Limitations

Sedum blankets help some insects find food, good for bees in late spring. But they’re not enough for many other city wildlife. Using a mix of plants, especially native flowers, makes green roofs even better for biodiversity.

Green roof biodiversity

Biodiversity on Extensive Green Roofs

Studies in Switzerland and the UK show extensive green roofs help wildlife. Many insects from dry grasslands come to these roofs. They are key spots for Habitat Restoration and Biodiversity Conservation in Urban Ecology.

Invertebrate and Pollinator Habitats

Ground nesting birds like the Skylark and Common Tern make homes on green roofs. This helps create Urban Ecology and Sustainable Cities. They turn roofs into important Rooftop Gardens.

Ground Nesting Birds on Green Roofs

In cities, green roofs are great for bird feeding areas, like for the Black Redstart. Birds like Goldfinches from Europe love these spots. These roofs are big for Green Roofs in Promoting Urban Biodiversity.

Foraging Habitat for Urban Birds

Using Eco-friendly Architecture benefits birds in Urban Areas. It includes Rooftop Gardens that promote Biodiversity Conservation. These are essential in crowded cities.

Green Roofs in Promoting Urban Biodiversity

Semi-Intensive and Intensive Green Roofs

Semi-intensive and intensive green roofs look like gardens. They attract lots of wildlife. They should be designed well, using both native and non-native plants.

Garden Spaces for Wildlife

Intensive green roofs are mainly for people. But, they create a mini-habitat in cities by planting natives like herbs, shrubs, and trees. This boosts urban ecology and helps save different species.

Native Plantings for Biodiversity

Using a mix of native and non-native plants on green roofs can help many kinds of animals. It makes these areas better for nature. This also makes cities more ecofriendly and strong against problems.


The wide use of green roof techniques is key in boosting urban biodiversity. They offer important ecological spaces in busy cities. These roofs give homes to many insects and nesting places for birds. Many studies have looked at the extra biodiversity benefits urban green roofs bring.

Understanding how green roofs help urban species is key. This helps in making cities better for urban biodiversity. Knowing the conservation value of these areas is also crucial. Eco-friendly architecture, sustainable cities, and rooftop gardens play a big part in saving and growing urban ecology.

Working to lower the environmental impact of cities is vital. This includes fighting climate change. Using green roofs in urban planning can greatly help. It promises to make cities better and full of life in the future.


What is the threat of urbanisation to biodiversity?

Urbanisation’s fast growth threatens biodiversity. Yet, cities can also be great for rare plants and animals. This includes species at risk both locally and worldwide.

How can green spaces help promote urban biodiversity?

Green spaces are vital for bringing more living things into cities. They need to be plentiful, well-designed, and work together. As cities get busier, having green areas like roofs is more important than ever.

What are the key components and benefits of green roofs?

Green roofs are covered with living plants and a special soil layer on top of a roof. They help with water, save on energy, and make cities cooler. Animals and plants can also live on them, adding to city life.

How can green roofs support urban biodiversity?

Green roofs are like homes for bugs and birds, including some harder-to-find species. Sometimes, new plants grow there on their own, carried by the wind or birds. Despite this, we still need more research to show how beneficial green roofs are to urban wildlife.

What are the key principles for designing green roofs to promote biodiversity?

To help create more life, a green roof should be deep and full of different plants. A well-made roof can be a home for many creatures, including birds looking for food. Where possible, we should use local plants to support the environment.

What were the findings of the case study comparing a green roof and a conventional roof?

A study in Barangaroo, Sydney, looked at two roofs. It found more types of species living on the green than the traditional roof. The green roof had birds, snails, and insects, while the other roof had less.

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Written by: Jackie De Burca

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