Biodiversity

Bioswales

Bioswales can play a large(r) role as ecological corridors and promote biodiversity. If the plants used are more varied and taller than just grass, many animals including birds, small mammals, amphibians and insects can find habitat.

Swales are often sown with grass mixtures that can withstand longer periods of drought. With more variety in the planting – in the form of herbs, perennials, shrubs, trees and even flower bulbs – bioswales are more resistant to alternating dry and wet periods (grass is less able to withstand this). More plant variety is more attractive to animals and humans.

Naturally designed bioswales require less maintenance than grass-only bioswales. They don’t need to be mowed often. There is less chance of being entered by people, dogs and cats.

In order to strengthen biodiversity in the city, it is important that there is at least one large green area that is extensively managed and is part of the green network in the city.

More green connections

Combinations of green with grey and red are also valuable. Consider green networks of (railway) roadsides, roundabouts, embankments, avenues, streets, squares, roofs and facades, which connect the public space (e.g. parks), gardens, buildings and the landscape. Animals that can’t fly can use these networks to expand their habitat.

To support flying animals, such as bats, birds, bees, bumblebees, wasps, moths, and butterflies, it is desirable that green areas are connected to each other as a networks through the city. Patches of habitat should be spread out, but not too far apart (no more than 500 meters), and preferably with food sources in between.

Ecoducts

The construction of fauna passages and ecoducts (bridges for animals) has created a considerable measure of new nature. Research shows that these structures increase the habitats of many wild animals, including include wolves, wild boars, otters, deer, badgers, salamanders, frogs and bats. Their habitats had become unnaturally small due to the construction of roads, waterways and railways. Wildlife passages and wildlife crossings provide these animals with access to food and shelter and make it easier to find a suitable mate. Animals can cross safely, reducing the number of fauna casualties caused by collisions with road and train traffic or drowning.

Defragmentation of nature by realising ecoducts in particular is the most effective, yet is achieved at the greatest financial cost. Shared use facilities (humans and animals) and large fauna tunnels may be more cost effective.

Soil

Biodiversity starts with the soil. A healthy soil with a rich and healthy soil life improves infiltration and water retention and produces healthy plants. This reduces the need and cost of pest and disease control. When no chemical pesticides are used, no harmful substances end up in the food chain.

Pollination

Pollination and pollinators are essential for biodiversity. Insects provide pollination and help to maintain plant species. Insects, eggs, and caterpillars of the pollinators serve as food for other animals. Pollination produces seeds, fruits and berries that are eaten by many birds, mammals and humans.

Honeybees, solitary bees, bumblebees, wasps, and butterflies are essential for pollination. These insects depend on sufficient pollen- and nectar-rich plants in their environment.

Butterfly idylls are places full of flowers for people to enjoy and for butterflies and bees to survive. To support butterflies, it is important to select plants that provide food and drink for both butterflies and caterpillars. Success requires support from people involved in the idyll (e.g. the landowner, local residents, nature clubs and schoolchildren) and management by an expert party. A limited mowing regime and mowing in two stages, encourages a flower meadow to grow.

Plant species that are under pressure in rural areas often grow in flower meadows. Investments in a living public space that demonstrably contribute to the enhancement of biodiversity are eligible for investment deduction (MIA/Vamil) in the Netherlands. This is interesting, for example, for a sports or industrial estate.

Recreational lawns can include more flowering plants, such as dandelion and clover.

Review

In cities, there is not always room for flowery grassland. It is important that there are flowers all year round, not just in spring or autumn. Large, healthy flowering trees and shrubs can be an important source of food, producing good quantities of nectar and pollen. Consider linden and hawthorn, and also of exotic species such as false acacia.

There is a varied range of pollen- and nectar-rich trees and shrubs which are an alternative to the commonly chosen species.

Birds benefit from varied planting with a range of heights. Trees provide views, food, safety and support breeding by providing nesting habitat.

Including trees in an urban ecosystem increases variation and structure, which promotes biodiversity. This is greatly facilitated by the presence of undergrowth and naturally dead wood. Natural forests are often hotspots for biodiversity.

In cities, species richness is higher in urban forests than in green areas without trees. Biodiversity is often greater at the edges of a forest than in the middle (due to more light), which is the reason why smaller (urban) forests with relatively lighter peripheral areas are valuable. Parks and other woodland areas can act as ‘islands of biodiversity’ in urban areas. Greenery in the city can be a refuge for endangered species and offers good opportunities for reversing biodiversity loss.

Ecological barbed wire

A natural impenetrable hedge is a good alternative to a fence with surveillance cameras around a site. Thorny hedges also provide nesting opportunities. A flowering mixed hedge is very suitable for enhanced biodiversity, with the added advantage that it requires less (precise) pruning.

Roof and façade greenery

A green roof attracts many kinds of small insects, which in turn attract birds. Special biodiversity roofs have been developed. Façade greenery in the form of climbing plants, provides food and shelter for numerous birds and insects.

Nature-inclusive construction is only effective if the structures provided for fauna are sensitive to the likely species in the area and if food and habitat can be found nearby. It is the relationship between building and environment that matters. One can learn from good examples in other places, but they cannot always be copied exactly one-to-one at another location.

Nature-inclusive construction is more than just installing nesting facilities in or on buildings. If there is no food to be found in the area, there will be no bees, butterflies, birds or bats.

Exemption

Incentives to encourage design and construction practices to support nature vary around the world

In the Netherlands, until recently, sites were kept free of nature to prevent the establishment of protected plants and animals. That is no longer necessary. With the Temporary Nature Scheme, exemptions can be obtained in advance for the species that may be able to settle on a site. With this scheme, nature (more species) can temporarily emerge in places that would otherwise remain barren and unused. This makes it more attractive for project developers to give an area a temporary green interpretation. In addition, mowing is less frequent.

A nature-friendly and a low-maintenance outdoor space go well together.

Nature-inclusive construction is a way to comply with the Nature Conservation Act. If nature-inclusive construction is carried out on the basis of a species management plan, this can be used to compensate for the loss of places for animals to stay elsewhere in the area. In that case, there is no risk of fines or delays due to the shutdown of work.