Plant facade
Contenido
En total, las fachadas del Bosco Verticale albergan 711 árboles, 5000 arbustos de grandes dimensiones y 15 000 plantas perennes y de hoja caduca, que se densifican en altura hasta recubrir una superficie equivalente a dos hectáreas (20 000 m²) de vegetación.[25] Hay 94 especies vegetales distintas: de estas, 59 son útiles para los pájaros, 60 son árboles y arbustos y 33 son se hoja perenne.[25].
Benefits
The vegetation provides numerous beneficial effects to the two towers and the urban environment that surrounds them, both from an environmental and climatic point of view. The Bosco Verticale contributes to the constitution of a microclimate that generates humidity, filters suspended particles (or diverts their path), significantly attenuates noise pollution, purifies the air by removing CO from the atmosphere and emitting O, protects from solar radiation through the shade of the leaves and protects from the wind through the wind-breaking action of the plants.[26].
From the point of view of fauna, Bosco protects biodiversity through the creation of biological habitats. The numerous plant species distributed on the facades constitute a true ecosystem capable of attracting birds and insects (1,600 were counted in 2014),[25] "becoming an urban sensor of the spontaneous plant and animal recolonization of the city."[27].
The Bosco Verticale is also a device against urban dispersion that "contributes to controlling and reducing urban expansion": if it were distributed uniformly over the territory in the form of single-family houses, each of the two towers would occupy an area of about 50,000 m².[27].
In the words of Stefano Boeri:
Arrangement of species and polychromy
Another peculiarity of the Bosco Verticale is the changing polychrome of the trees that cover its facades. With the passing of the seasons, the plants not only renew their colors, but also those of the entire architecture: thus, during spring the two towers assume delicate pastel tones, while in autumn, at the end of the growing season, warm colors emerge.[29].
Nor is the distribution of species a product of chance. In this sense, the plants were placed based on several criteria of a formal and aesthetic nature; For example, its ornamental qualities, flowering seasons, potential allergenicity, development of foliage and trunk architecture, and ease of maintenance are cited. In this way, evergreen plants are placed on the southwest side, while deciduous plants are placed on the northeast side.[30].
A good summary of what we have just said is given by Laura Gatti, the landscape agronomist who, together with Emanuela Borio, supervised the plant façade of the complex:[31].
Below is a table that shows the colors assumed by some of the plant species during the four seasons.[32].
Containers
Each of the containers in which the species are planted has been designed so as not to excessively influence the growth of the roots, avoiding the appearance of defects. The dimensions of the container vary according to the water and radical requirements of the plant; In the case of trees, they have a length of 1.10 meters and the same width, while for shrubs, containers of at least 0.5 meters in length and depth were adopted.[33].
All containers are made of cement and equipped with a waterproof bituminous layer and a protective coating capable of effectively limiting radiation. Along the interior surfaces there is a separation and drainage layer to separate the substrate from the waterproofing membrane, placed at the bottom of the container: the latter is made up of non-synthetic fabric filter elements, respectively a type of geotextile and a polyethylene anti-root cover.[34].
To anchor the plants, a solid welded steel frame was used, capable of effectively anchoring the land affected by the establishment;[34] in the case in which the tree in question reached considerable dimensions, other steel hooking systems were adopted, this time aerial.[35] The anchoring systems, among other things, do not only involve the containers, but also the plants, protected by temporary link devices to prevent them from overturning or falling, especially in conditions extreme and unforeseen environmental conditions.[36].
The cultivation substrate for all Bosco flora is composed of mixed organic and inorganic substances:[37] the masterful use of lapilli stands out, a porous volcanic slag that, due to its characteristics, has high water retention, optimal cationic exchange capacities and substantial durability over time.[33].
Identification codes
Each of the plants present in Bosch is unequivocally identified by a sequence of numbers and alphabetical characters. To find this code, it is enough to precisely determine the scientific name of the plant and the location (floor and terrace), such as:
The first two characters are the initials of the scientific name of the species (in this case, the holm oak, or Quercus ilex); The two subsequent sets of characters identify the floor number (the second) and the code of the terrace (V01) where it is located.[38].
Irrigation
Trees are watered using a centrally maintained drip irrigation system. The water it uses is not potable, but is recovered from the gray water produced by the building or from the aquifer slope.[39] This, once accumulated in a cistern, flows through a network of visible irrigation conduits that have a very low resistance to low temperatures and automatically block the water regime in the event that it is below zero degrees;[40] this control is completed by a series of remote monitoring probes that can also identify eventual breakdowns.[41].
The water supply to each plant is guaranteed by a control device composed of a relief valve, a pressure regulator and a filter unit. The electrically operated irrigation also takes into account the real needs of the vegetation: each valve is independent of the others, so as to guarantee the ideal flow of water. At this point, an automatic air valve and a drip wing allow irrigation of the growing substrate of each plant.[40].