In a Biodiverse Garden, the Mind Finds Ease
Testo in italiano al seguente link
Just as our home welcomes us, cares for us and provides us with a table around which to gather, so too does the outdoor space, the garden, become a place where nature massages our soul and recharges us after long days at work. A place to party and play, grow herbs and vegetables, but also read under the branches of a tree or simply breathe.
Often, outdoor space is designed when the building is almost complete and the budget is running low. This is a shame, because many scientific studies confirm that the physical and mental health benefits of a quality natural environment are enormous: blood pressure is reduced, the immune system is strengthened, and mental fatigue is alleviated. Exposure to natural light stimulates the production of vitamin D and increases the production of serotonin, helping to restore good mood.
Integrated view of environmental aspects
The SNBS standard has the merit of taking a 360° view of environmental issues in construction. While it is true that many designers perceive standards and labels as limiting and a hindrance to creativity, it should be emphasised that SNBS is one of the very few standards that has “thought things through to the end”, looking at the interaction between different environmental, economic and social sectors, as well as between the built and natural environments. The criteria are described in a comprehensive and very practical manner and can be used as a guide from the early stages of design, even beyond certification.
The objectives pursued are climate protection, adaptation to climate change, protection and sustainable use of water resources, transition to a circular economy, prevention and reduction of pollution, and protection and restoration of biodiversity. This article focuses on biodiversity.
Biodiversity: from the construction site to the definition of species
The image evoked when thinking of an ideal outdoor space is (very) different for each of us: from rustic gardens with flower-filled lawns, fruit trees and many small microhabitats, to natural-looking, well-tended English gardens, to minimalist Japanese gardens with a few tufts of grass and water features. The design of outdoor spaces is therefore just as varied.
An important first step, which should be taken from the early stages of design, is to examine the existing situation and decide how you want to use the outdoor space. Important design choices depend on these initial assessments.
When assessing the existing situation, it is advisable to observe what is present on the map and the context in which you find yourself. If you are working on an existing building, renovating or demolishing it, you need to examine whether it is used by small wildlife as a nesting or wintering site. Swifts, for example, breed almost exclusively in building niches, near the roof or between tiles. They therefore depend on cavities in buildings, to which they remain loyal for decades and which are put at risk in the event of construction work. Other animals such as house martins, bats and various species of insects, including some butterflies that hibernate in attics if conditions allow, also find refuge in buildings (or in their vicinity). The existing vegetation must also be assessed: if there are old trees with thick foliage, hedges or rows of native trees on the plot, these should be preserved. They are, in fact, valuable for regulating the microclimate and are of great value to the existing local fauna. Furthermore, these trees or shrubs have already “proven” that they are adapted to the site. This aspect must be carefully evaluated during the design phase, as it may be necessary to adjust the position of the buildings according to the existing valuable vegetation. In the case of renovation, it is possible to create alternative habitats during the construction phase or to carry out the work when the animals are absent from the buildings. For swifts, for example, there are nest boxes that can be placed on scaffolding as possible temporary nesting cavities. During the design phase, the creation of niches and access points to the new or renovated building should be planned, as well as the installation of artificial nests.
The context in which the property is located is equally important: if, for example, there are groves or protected natural areas in the surrounding area, or if it is located along an ecological transit axis connecting several habitats important for small fauna, this must be taken into account. In this case, the horizontal permeability of the site must be maintained by removing all obstacles to the passage of small wildlife. Close-meshed fences reaching down to the ground, closed walls or steps higher than 10 cm should therefore be avoided. On the other hand, wildlife must be protected from hazards, such as ventilation grilles or swimming pools, by installing exit aids or protective devices. Unnecessary light emissions and glass windows can also pose a danger to wildlife.
Welcome laziness!
In the garden and in outdoor spaces in general, it is possible to effectively promote the natural habitat with just a few simple measures. Paradoxically, laziness could be the main driving force: mowing the lawn less often, leaving fallen leaves on the ground, accumulating wood and stones in the right places, even if a little haphazardly. Together with minimal control of invasive neophytes, this is the perfect recipe for transforming your garden into an area rich in biodiversity. For those who are ready to do and give more, it is essential that the outdoor space has native vegetation that is as rich as possible in species suitable for the site and that there are structures in place to provide shelter and raw materials (food and nesting materials) for different animal species. Ideally, the vegetation should flower from spring to autumn, thanks to the sowing or planting of species that flower at different times, and produce small fruits. The presence of thorny species is essential: they create a physical barrier that allows small fauna, such as hedgehogs, to enter the vegetation and find shelter and safety from predators, but also to be used as a pantry (see “Interesting facts” below). Wood piles provide shelter, but also food or, for example, ideal places for insects that specialise in dead wood to lay their eggs.
Mitigating the effects of climate change
Another key aspect is the implementation of effective measures to combat the heat island effect and adapt to climate change: trees with large crowns, permeable and greened surfaces that allow surface infiltration, filter ditches and other water retention structures help to modulate the water cycle and reduce the local temperature. As far as buildings are concerned, green roofs and facades not only promote biodiversity, but are also effective measures in terms of microclimate and rainwater management. A green roof can absorb 50% to 95% of annual rainfall, releasing water gradually in the hours following rainfall, and the temperature on the building is up to 20–40 °C lower than on a flat roof covered with gravel.
The outdoor space must be liveable
If the garden will be used by children, a section of mowed lawn should be provided so that they can play football safely. if a tenant suffers from allergies to certain animals or phobias, this must be taken into account; if there are elderly people, priority should be given to trees that provide shade and cooling; and for those who want to exercise and have locally sourced food, a large vegetable garden should be created with a water supply nearby. There are many possible measures, and it is essential that each project is tailored to those who will use the outdoor spaces.
Progettare e gestire in maniera corretta uno spazio esterno che metta al centro natura e essere umano è complesso e richiede una consulenza specialistica – peraltro offerta da alcuni Comuni o alcune associazioni ambientali come Pro Natura – ma ha un valore inestimabile in termini di benessere personale e per la collettività. A biodiverse garden is the ideal place to unwind and let your soul breathe.
“The miracle is not to walk on water, but to walk on green earth in the present moment and appreciate the beauty and peace that are available now”. Thich Nhat Hanh
The divining tree that refreshes us
The common oak (Quercus robur) is one of the trees with a high capacity to cool the surrounding air through evapotranspiration and is able to sequester CO2 and pollutants from the air. It is a very long-lived tree with a wide crown and can reach a height of up to 40 metres. Its acorns are particularly appreciated by the elegant and colourful jay, which collects up to 11 kg for its winter supplies. It has also been discovered that around 400 species of butterflies depend on this tree, as well as many other species of insects, spiders, birds and mammals. Last but not least, it was the tree sacred to Zeus and a symbol of strength and power, also used as an oracle.
Curiosity
Winged Zorro (reference in the text)
The red-backed shrike, whose male is easily recognisable thanks to its black Zorro-like eye patch, grey head and rust-coloured back, is one of the species that depends on thorny shrubs. Its peculiarity is that it impales surplus prey on thorns, thus keeping a supply for lean periods. It also prefers thorny shrubs for nesting: when choosing the right shrub, the female has the final say, after the male has shown her several examples.
Food delivery arrives by train
Researchers at the University of Zurich have discovered that sparrows wait for trains arriving at Zurich Central Station to peck at insects that have been hit during the journey from the glass and locomotive. They have even observed that sparrows seem to prefer and specifically wait for regional trains, which are slower and richer in food.
Natural mosquito repellents
Spiders, wasps, swifts, flycatchers, but also reptiles and bats: they all feed on insects, including mosquitoes, which are such a nuisance in summer. During the breeding season, if conditions are favourable, a pair of swifts can catch up to 20,000 winged insects per day, including mosquitoes, flies, wasps and aphids. A bat can eat up to 2,000 mosquitoes per night. A good reason to have them around.