Last 16 December, Milan hosted Veg-Gap workshop for the presentation of the project. The project’s partner representatives met at the
Training Hall of Milan City. The meeting “Milan changes air – the role of urban forestation” was organized by Città Resilienti project
management for Milan City. As already done in Bologna in October and in Madrid in early December, the aim was to introduce, at a local
level, the actions envisaged by the European project LIFE Veg-GAP "Vegetation for urban green air quality plans" and to explore the relation
between the project and the current local environmental strategies related to air quality, green infrastructure and Milan's adaptation
to climate change.
Works were introduced by Piero Pelizzaro, Chief Resilience Officer for Milan City, and by the project’s coordinator Mihaela Mircea of Enea.
Space was then dedicated to two reports, which made the point on what has already been detected and done, as part of Veg-GAP project,
in the cityof Milan.
Alessandro Alivernini of CREA (Council for Agricultural Research and Agricultural Economy Analysis), project partner, presented the
methodology used to elaborate the overall vegetation map of Milan. From the species database, which was provided by the Municipality
of Milan, botanical analyzes were carried out on the vegetable component: altogether there are 242 species in the city but 80% of the
tree population is represented by just 16 species, of which Celtis australis, followed by Platanus x acerifolia and Carpinus betulus are
the most common. The specific value of pollution mitigation, CO2 sequestration and potential emission values of Isoprene and Monoterpenes
(BVOC, Volatile Organic Compounds of biogenic origin) were then defined for each species.
Sandro Finardi of ARIANET, another project partner, presented the method for calculating biogenic emissions of volatile organic compounds
on the basis of the individual plant species present on the territory. He stressed the need to build a plant cover database that includes the
tree population present within urban and agricultural areas.
This information base was built by integrating the municipal census of trees and the regional forest map with the use of level 4 CORINE Land
Cover. The Veg-GAP project innovation was illustrated by comparing the tree cover and isoprene and monoterpenes (BVOCs) emissions,
with those that would have produced by a traditional modeling approach, which neglects the presence of trees within the urban fabric.
Finally, it was stressed that the VEG-GAP project is a first step towards the integration of urban vegetation effects and reforestation plans
into modeling analysis in support of air quality plans.
Three tables then began to work on specific topics. The first one dealt with Veg-GAP and about how to promote the relation and the data
exchange between Veg-GAP project and Milan Air and Climate Plan. During the discussion, a sensitive issue emerged concerning the recent commitment by city administration of Milan to propose massive tree-planting interventions and the information provided by the Air and
Climate Plan on the plants better suited to absorb pollutants. The concern revealed by the table, especially by administration’s members,
is if Veg-Gap project might risk making interventions or providing indications that could be negative and counterproductive.
For this reason, providing a list of the species to “ban”, or in any case to plant in reduced number within areas where the ozone concentration
is already high, was considered a matter of priority, in order to take into account both the emission and absorption aspects.
Another aspect that has attracted great interest and attention consists in the green infrastructures, in particular green roofs, a topical and
interesting theme from different points of view: cooling, energy efficiency and social cohesion. In this sense, it is necessary to deepen the interactions and results already acquired by the projects, Decumanus and Clever Cities, in which the City of Milan participates as a partner,
in order to promote synergies and to avoid overlaps.
The second working table dealt with the urban forestation program and with the impacts on air quality in order to understand if the database
taken into account until now by VEG-GAP project could be further implemented and in order to explore vegetation scenarios for the City
of Milan that may be as significant, plausible and feasible as possible, and finally subject them to the modeling developed by the project.
The table proposed the use of PIF (Piano di Indirizzo Forestale) and the forest management plans to update the datasets with some wooded
areas currently not present in, and to train the algorithm to recognize species from satellite images. These data are potentially useful,
above all for the classification of the Metropolitan City’s trees, which doesn’t have exhaustive databases about its heritage.
Furthermore, Parco Nord has a detailed knowledge of the arboreal heritage present inside the park, approximately 140 hectares (wooded
areas, rows and shrubs). They propose to find these data for a validation of the obtained results. The Urban Forestry Program, ForestaMI,
has its own database created on the basis of the topographic one. At the same time, they also worked from below, asking individual
municipalities to indicate possible planting areas.
During the discussion, the possibility emerged to use other more exact databases, such as the RELambro, Open Agri and Cà Granda Foundation projects’ ones.
Regarding the exploration of new vegetation scenarios, the discussion was oriented towards three possible scenarios:
● Inside the PGT, recently approved Piano di Governo del Territorio, which will govern Milan’s visions and projects by 2030, the largest
planting area concerns 10,000 square meter in the 20 new parks and planned railway yards, projects that are expected to be implemented
by 2030 and which provide useful material to be submitted to the model.
● Another considered area consists in roofs. The study carried out by the City of Milan as part of the Decumanus project identified the roofs potentially suitable for hosting green spaces, which can be used as a possible scenario in the VEG-GAP modeling, in order to evaluate its effectiveness compared to the urban-scale effects on air quality.
● The parking area was taken into account, a promising area for the need expressed by the adjustment guidelines now at the drafting stage,
to provide for the shading of parking places, for urban cooling purpose; regarding the concrete feasibility of new trees planting, a precise
and in-depth verification is necessary.
The debate and sharing that took place during the workshop raised ideas for further checks and arguments. For an exact calculation of the emissions, the first necessary step is to carry out a mapping of the vegetation present in the territory of Milan, as exhaustive as possible,
including the metropolitan city. The participants in the Air Table and in particular those who provide for drawing up the Air and Climate Plan,
will be able to integrate the document they are preparing about air quality requirements, including the biogenic sources assessed and
simulated in the project among the emission sources. In forecasting the tree species to be used for the City of Milan’s Planting Plans,
biodiversity must be preserved and ensured. This is an aspect that will have to be taken into account when specifying the most suitable
species within Milan context, together with aspects related to maintenance costs. The roofs’ scenario that the project intends to analyze
will be the subject of a specific working table in the coming months.