Urban nature is surprisingly diverse

Nature and biodiversity must be nurtured in cities as well. Diverse nature benefits urban residents too. Verdant spots protect against heat, reduce stress and expose us to beneficial bacteria.

What’s the point of urban nature or its diversity? After all, Finland has a lot of forests and rural areas. This provocative question may arise when the conservation of urban nature comes up in conversation.

Susanna Lehvävirta, director of the Helsinki Institute of Sustainability Science at the University of Helsinki, has the answer: urban nature may well be more diverse and richer in terms of nature than monotonous production forests or, for example, drained peatland.

Fragmented urban nature is usually managed differently from commercial forests. Trees are allowed to grow large, and there is space also for decaying wood.

“There are surprisingly old trees in the forests of Helsinki, and aspen stands that provide habitats, for example, to flying squirrels as well as endangered mosses and bracket fungi,” Lehvävirta says.

Furthermore, what benefits urban nature also benefits urban residents. Vegetation provides cooling in hot weather, helps manage drainage water and prevents flooding. There is also plenty of research-based knowledge available on the effects of nature on wellbeing and health.

Taking advantage of research knowledge

Lehvävirta thinks municipalities should make every effort to preserve urban nature.

At the moment, a critical decade is underway in terms of curbing both biodiversity loss and climate change. The same solutions can be used to tackle both crises.

“There is already a lot of research-based knowledge available. By utilising it more broadly, decision-makers and authorities, urban planners and landscape architects would take an enormous leap forward in this area,” Lehvävirta estimates.

For the time being, Finnish municipalities have not utilised research adequately to prevent biodiversity loss and to reconcile human activity with nature. According to Lehvävirta, this is partly because of urgency, partly because of ignorance.

In fact, she is calling for universities to acknowledge the value of knowledge brokering. Researchers should actively broker their knowhow in support of urban planning.

“And the latest research-based knowledge in the field of sustainability should be included in the training of engineers and landscape architects. We also need continuing education.”

Lehvävirta wonders whether researchers’ expertise could be shared on social media too. For example, information on alien species or the benefits of the controlled non-management of home gardens could reach many thousands of urban residents in gardening-themed social media groups.

Nature solves human problems

And what kind of solutions could cities use to foster biodiversity while also enjoying all the positives that nature offers us?

Lehvävirta points first to the urban floods that have recently become a headline. Basements are flooded when the drains do not run. The damage caused generates great costs for residents, entrepreneurs and municipalities.

Floods would most likely be less frequent if we built green roofs and had more trees, bushes and permeable surfaces instead of asphalted ones. Increasing vegetation would also be an inexpensive solution. The management of drainage water is less expensive above the ground than beneath it.

“Individual trees can hold as much as 100% of the precipitation that falls on them. The water accumulates in the leaves or needles, slowly flowing down the branches and the trunk. At the same time, the tree provides a habitat for numerous epiphytes and insects, and can serve as a nesting place for birds or a route for flying squirrels. In the heat of the summer, the same tree offers shade and cooling.”

Plant choices in green areas and parks also make a difference. Should you plant in the flowerbed a plant that is found in the wild in Finland, or one that will turn out to be a harmful alien species in the future?

Researchers are monitoring alien species lists in the regions neighbouring Finland. If a species begins to spread rapidly in Sweden, it is likely sooner or late to do the same in Finland as well.

“We are currently fighting, among other species, the Himalayan balsam, the rugosa rose and the Canada goldenrod. The latter was added to the list of invasive species in August. In some places, it is already a big problem.”

Eradicating invasive species that appropriate living space from local wild species is difficult and expensive. In fact, municipalities can save millions of euros by favouring native species.

Another simple trick for nurturing the diversity of urban nature is lighting design. Dimming outdoor lighting or using motion detectors would reduce light pollution that is harmful to nocturnal animals.

Beneficial bacteria

The effect of nature on mental wellbeing has long been the subject of investigation. Spending time in nature and lush landscapes have been found to reduce stress hormone levels and blood pressure, as well as boosting creativity and learning ability. Verdancy also inspires people to exercise.

Recently, research has also been conducted on physical health effects.

Doctoral Researcher Mika Saarenpää from the Helsinki Institute of Sustainability Science investigates the effect of natural microflora on our immune system.

“The less exposed we are to natural bacteria, the more easily our bodies start to fight threats that are not actually threats. The immune system goes into overdrive, making allergies and autoimmune diseases increasingly common.”

Autoimmune diseases include type 1 diabetes and inflammatory bowel diseases.

Saarenpää investigates whether increasing urban greenness could increase exposure to bacteria and, consequently, prevent diseases.

“Plants and other organic material, such as decaying wood, should be added especially to the courtyards of daycare centres and playgrounds, as the immune system develops rapidly in childhood. Existing nature should also be fostered. In terms of microbial exposure, woods that start in the back garden are important. They are used by everyone – children, joggers, dog walkers and older adults.”

Too many animal and plant species are already endangered. If we don't act now, whole ecosystems are in danger of collapse.

Knowledge gives us hope. Donate now and help us to stop nature loss.