“The preservation of biodiversity is not just a job for governments. International and non-governmental organisations, the private sector and each and every individual have a role to play in changing entrenched outlooks and ending destructive patterns of behaviour.” ― Kofi Annan
Cities are growing while natural areas are shrinking. But even in urban environments, we find green spaces that offer home to many species, making it all the more important to promote nature in such human-dominated landscapes. We are two members of a research team that recently examined the biodiversity of domestic gardens in the city of Basel and its surroundings. We focused on a diversity that is often overlooked but plays an essential role in the ecosystem: the small ground-dwelling invertebrates that we unconsciously may trample beneath our feet. In our just-published article, we analyze to which degree urbanization and local characteristics affect the diversity of these little animals.
As part of this ongoing research project, we interviewed the Basel garden owners to explore how their management decisions affect biodiversity. In this way, we learned much about the gardeners’ views and motivations, and found an amazing species diversity while surveying their gardens. In what follows, we would like to share some of our insights and provide five tips on how to promote biodiversity in private gardens. For even now, in the fall, there is plenty you can do!
Dare to be chaotic! Allow at least part of your grassland to grow over more extended periods. This yields valuable habitat for many species, and the beautiful flowers attract pollinators like butterflies and bees. Also, don’t trim all your flowers and shrubs when they are wilted. Many animals still love them. Even fallen leaves and branches provide attractive homes. Not to mention dead tree trunks: they are highly popular among many beetles and other animals.
Go regional. Native plants will increase the diversity of insects and other animals in your garden. Why? Because compared to exotic plants, they are much more suitable as habitat and food resource for local species. Moreover, choosing regional plants will also help to prevent a problem relevant to nature conservation: many non-native plants, including some popular garden plants, can become troublesome invasive species that will spread and colonize habitats outside of your garden. And since they have few natural enemies in our region, they can spread massively and displace native species. Governments worldwide spend a lot of money to contain such invasive species.
Be nature’s architect. Different animal have different requirements. If your garden offers a high habitat diversity, chances are good that you garden will become home to a wide range of animal species. Even small structures, like piles of stones, can offer valuable homes. The same is true for compost heaps and ponds. Compost, in particular, provides an essential food resource for many animals. Among our gardens, those with a compost heap had more ant and snail species than those without. Artificial structures, as well, can be beneficial, such as bird boxes, earwig houses or hedgehog shelters. However, when setting these up, carefully follow recommended specifications, to not accidentally create a structure that is detrimental to the occupants’ survival.
Trust nature. Pesticides and herbicides not only affect target species ― some remain in the environment for long periods. Better to find ways to promote natural enemies by providing suitable habitats that balance nature and prevent pest insects and weeds from getting out of control. Remember, even “organic” snail bait is usually poisonous and it affects those snail species that actually don’t eat your veggies! Indeed many snail species feed on dead plant material and contribute to the recycling of nutrients. To supplement natural enemies’ work, you can also apply alternative methods like weeding and installing snail repellent fencing. The same goes for artificial fertilizers: Preferably go for eco-friendly alternatives such as compost or use them with restraint.
Inform yourself and be patient. Many garden owners are highly motivated to promote biodiversity. Unfortunately, the beneficial effects of their efforts may be limited by gaps in their knowledge. Garden owners frequently miss the magnitude of biodiversity already in place and the potential for improvements. Fortunately, there are many valuable resources on the internet, including which native plants to promote as food resources for insects. Importantly, garden owners should persist in their efforts: Allowing enough time for the plants to grow and for animals to detect their new homes.
As you step out into your garden, you will also embark on a path of discovery. Observing closely how your plants grow and how new species move in, will allow you to learn about them, and to find new ways to promote biodiversity. Importantly, it will also be a constant source of joy.
About the authors: Brigitte Braschler is a researcher, and Valerie Zwahlen a PhD student in the Conservation Biology unit of the Department of Environmental Sciences at the University of Basel. They are ecologists interested in protecting biodiversity and they hope that this article inspires readers to promote nature at their doorsteps.
The authors want to thank the Basel garden owners for welcoming us to their private domains, as well as for their interest in our findings and willingness to improve their gardens for biodiversity.
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