«Settlement areas have great potential for more biodiversity»

In this interview, biodiversity expert Maria Sautter from the consultancy firm intep explains how the diversity of plant and animal life can be promoted on built-up areas and which conflicting objectives need to be resolved.

Ms. Sautter, what exactly is meant by the term “biodiversity”?

It refers to biological diversity, i.e. the diversity of life. This includes species diversity with animals, plants and fungi, but also genetic diversity within species with varieties and breeds. It also includes the diversity of habitats or ecosystems, such as forests, meadows and bodies of water.

When you think of biodiversity, images of these very habitats probably spring to mind. Are they still enough to preserve biodiversity today?

Unfortunately, only partially. Agricultural meadows and fields, as we know them in Switzerland, are often poor in structure and can therefore only be used by a few species. The use of fertilizers and pesticides is also problematic for biodiversity. Nutrient-poor and structurally rich meadows and fields with hedges, standard trees or dry stone walls would be valuable, but there are not many of these left in terms of area. Forests are of great importance for biodiversity, but are also under pressure because timber use, tourism and leisure activities in the forest are increasing. Here, protective measures and sustainable forestry are essential in order to preserve valuable habitats.

More and more land in Switzerland is being built on. How can biodiversity be promoted in urban areas?

Thanks to varied structures and different climatic conditions, urban areas have great potential for more biodiversity. Near-natural green spaces can provide habitats and connecting routes for various species. At the same time, there are further advantages: More greenery in the city improves air quality and reduces noise and heat, which improves the quality of life for residents.

What are the most important approaches to promoting biodiversity in built-up areas?

Trees are very important elements in built-up areas: they serve as retreats, nesting places and food for birds, small mammals and insects. The value of a tree for biodiversity and heat reduction increases with age. It is therefore important that a healthy tree population is preserved for a long time.

To protect wildlife, light pollution and the installation of large areas of reflective glass should be reduced. Light and glass act as traps and, if not used correctly, can lead to fatal accidents for birds, bats and insects. For this reason, protective measures such as effective bird protection markings should always be planned together with promotional measures such as façade greening.

Every green space is an added value for biodiversity, even small areas such as roadsides and tree grates. In order to specifically promote local biodiversity, the majority of plants used for greening should be native. This also applies to green roofs and façades, which provide additional habitats in densely built-up areas.

For which plants and animals is it difficult to provide a suitable habitat in built-up areas?

The densification of settlements and the heavy sealing of the soil make it difficult to create large and contiguous habitats. In addition, urban environments are often polluted by human activity, which deters sensitive species. For this reason, urban areas are not suitable for large mammals and specialized bird species that require large, undisturbed areas. Moisture-loving plants and animals can also only be supported to a limited extent, as habitats such as ponds and marshes need suitable climatic conditions to be maintained in the long term. This is often not the case in cities.

What do clients and specialist planners need to know if they want to integrate biodiversity into their construction project? What is the best way to proceed?

It is important to incorporate the topic early on in the construction process – preferably during strategic planning. If the site is analyzed in detail by a specialist, they can determine the local potential and develop specific objectives for biodiversity. On this basis, it is advisable to draw up a rough concept for the outdoor spaces as early as the preliminary planning stage, in which the position and type of green spaces and protective measures such as tree protection are defined. The concept can be refined in the later planning phases, for example with plant lists and small structures such as nesting aids. It is also important to define the maintenance requirements during the construction phase, as professional maintenance is the only way to promote biodiversity in the long term.

Are there suitable tools and guidelines for planning biodiversity measures?

The SIA standards 312 “Greening of roofs” and 491 “Avoidance of unnecessary light emissions in outdoor areas” are important aids in the construction sector. On the subject of bird protection, I can also recommend the Sempach Ornithological Institute’s leaflet “Bird-friendly building with glass and light”. In addition, more and more sustainability standards have defined biodiversity criteria and offer corresponding guidelines for planning and certification. In Switzerland, the SNBS and the DGNB System Switzerland have the highest requirements for biodiversity.

What conflicts of interest can arise when planning biodiversity measures and how can they be resolved?

Biodiversity requires space, and this is a precious commodity in urban areas. This conflict of objectives can be resolved by integrating green spaces into construction projects, for example through green roofs and facades, inner courtyards and community gardens. To avoid conflicts between people and animals, green spaces can be created and designated for different uses.

Another potential conflict of objectives can arise from the local production of renewable energy. The good news is that combining photovoltaics with green roofs or façades is technically possible and makes sense. If planned correctly, the systems even benefit from each other: the efficiency of the solar modules increases due to the evaporative cooling of the plants, which receive shade from the modules and thrive better.