How connecting isolated habitats can help nature flourish in our cities

Imagine you’re a fairy wren living in a patch of scrubland behind a suburban school yard. So far it’s been pretty good, but a recent increase in cats in the neighborhood and the council’s insect control tactics mean it’s time to start looking for a safer place to live.

There’s a problem, though. You’re a small, bright blue bird who tends to make short flights from bush to bush, safe in the foliage. Outside of your little patch of habitat, there don’t seem to be any places you can easily reach. On one side, there are sprawling sports fields; on the other, a busy six-lane highway. Where are you going?

It’s a bad situation for a fairy wren, and for many other native species in cities. In ecology, we call this habitat fragmentation.

The map of suitable habitats for urban wildlife often looks like a collection of islands in an inhospitable sea of ​​other land uses. These species face threats or barriers such as roads, buildings, fences and feral predators. This poses several problems, such as blocking access to feeding areas, increasing competition for nesting sites within habitats and even reducing gene flow by making it difficult to find mates.

Our research published in Landscape and urban planning shows how native species in our cities can benefit if we focus on creating strategically located green spaces that connect isolated patches of habitat.

Why we need to care for urban species

Despite the many challenges that plants, animals and insects face in urban areas, cities are important places to care for our native species. Urban areas still provide valuable nesting and feeding resources, especially for tree-dwelling mammals, canopy-feeding birds and aquatic-adapted species.

In addition to their conservation value, urban habitats are valuable places for people to encounter nature in the places where we live and work. Urban nature has been shown to be important in balancing the stresses of city life, particularly in underserved communities. It is also good for our physical health and social connectedness – even improving children’s cognitive development.

It’s no surprise that research shows that people want more nature in their cities.

But actively supporting native species is generally not the norm in many cities. The practice of planning and design to deliberately bring nature back into urban areas is still evolving. Our open-access research article in Landscape and Urban Planning offers insights into how we can address one aspect of the problem: habitat fragmentation.

What did the research look at?

We investigated how greening projects can best connect habitat for New Holland honeyeaters (Phylidonyris novaehollandiae), blue-banded bees (Amegilla spp.) and mole crickets (Gryllotalpa spp.) in Melbourne, Victoria. These are all species that occur locally but experience some degree of habitat fragmentation.

We need to green a lot for climate adaptation and to create open space for new residents in our growing cities. What if we could do this greening in a way that also increases the living environment for non-human residents?

We compared a scenario in which a large number of small green spaces (formerly parking lots) were created primarily for climate adaptation purposes with two scenarios in which a smaller number of green spaces were created exclusively in areas identified as important connections between habitat fragments.

What were the findings?

Overall, the benefit of each space in the target scenario was more than twice as great as in the scenario where we had created green spaces for climate adaptation purposes, even with the same design of the individual green spaces.

Here you see an image of the type of green spaces we modeled in this study.

We found that two of our three species benefited significantly from the location of green spaces that specifically targeted connectivity to their habitats.

Blue-banded bees and mole crickets did particularly well. These small creatures have a harder time navigating the space between habitat patches. When these small green spaces formed “stepping stones” between larger patches, they greatly increased the amount of habitat a bee or cricket could reach.

Connecting habitats when we create new green spaces is one way to give native species a chance in our cities. It also gives us (and our children) a better chance of experiencing nature every day.

Of course, adding this “ecosystem connectivity” lens to our green space planning is not a panacea for biodiversity. We will still need to deliver a lot of new green space.

And we will need to design it carefully to support native wildlife while providing cooling, reduced flood risk and recreational spaces. We also need to make sure we choose the right species to model our maps on, and then design our spaces.

But if we get this right, one day the wren may have little green ‘stepping stones’ to help them navigate their way through the city to a happy new home.

This article is republished from The Conversation under a Creative Commons license. Read the original article.