Pollinators in the city

In the beating heart of our cities, there is a hidden world that can give us so much and of which we are often unaware: the world of pollinators. Bees, butterflies, birds and other animals play a crucial role in urban ecosystems. Through their tireless work of pollination, they enrich the biodiversity of cities, making them greener and enabling the reproduction of many plant species. Greener cities mean higher air quality and greater psychological well-being of citizens. But the work of pollinators goes further: they are essential for the production of food, contributing to food security and giving us the opportunity to enjoy fresh, local food. Both by working directly in urban gardens and communal gardens, and indirectly through the production of food that flows from the countryside into the cities.

The pollinators are very good Bioindicators for climate resilience, their presence provides us with information on how well ecosystems (including cities) can be prepared to withstand the changes due to climate crisis. Over the last few years we have been good at excluding green from our cities and with the decrease in greenery, pollinators have also decreased. Now that we have recognised its importance, we know that this is a cost we cannot afford. What is the solution? To intervene directly with regeneration by creating new habitats where there are none and indirectly by raising awareness through education. Restoring a balance between pollinators and urban activities is not easy, the first step is to understand the state of health of pollinators in cities and then plan targeted interventions. But how can we obtain this data?

Traditional methods impose a search on the field of pollinators, but there are faster indirect methods to estimate their presence. We can exploit indices derived from information in the analysed environment that are able to return the data we need. In particular, we can do this by exploiting the CLC, Corine Land Cover, which is a methodology through which we can define different land uses: cultivated field, forest, buildings, car parks and so on. To each land use type we can associate different indices thanks to literature data.

Thanks to the 3Bee platform, we can do analyses based on the CLC (Corine Land Cover). Once we have drawn a well-defined perimeter, we can analyse the area within it and the surrounding area. From the map, the CLC (Corine Land Cover) of the area is generated, thanks to which we are able to allocate the site on the basis of land use. With this information, the indices mentioned in the following paragraph are calculated, which allow us to compare different sites.

1) Floral Availability: measures the availability of nutrients in an area, based on identified CLC classes; 2) Nesting suitability: the ability of a substrate to be suitable for nesting for a given pollinator species, calculated according to the identified CLC classes 3) Relative abundance of pollinators: measures the relative abundance of pollinators for a given map pixel. It is evaluated using 3Bee's proprietary software; 4) Nectariferous potential: the average nectar productivity of a plant species and its melliferous potential. It is estimated by associating the values given in the scientific literature with different land cover classes; 5) Average Abundance of Species by Land Use: the abundance of species living in a given area, in relation to the abundance that these species would have under natural and intact habitat conditions; These estimates are indirect and obtained thanks to the GLOBIO model.

To analyse the health status of pollinators in the city we have chosen:
1) Duomo di Milano, as we can see from the CLC, a heavily cemented and asphalted district, like most of the surface area of all the cities in Italy. Here we find a Pollinator Abundance of 1 unit and Nectar Potential of 3 kg/hectare/year.
. 2) City Life, a district of the city of Milan in which greenery has been systematically integrated into its design. In this site we find an Abundance of Pollinators equal to 7 units and Nectar Potential of 45 kg/hectare/year.

. 3) Lambro Park, a city park composed mainly of green areas and rich in biodiversity. In this site we find a Pollinator Abundance of 24 and Nectar Potential of 116 kg/hectare/year.

The data confirm what we might expect from urban environments in which biodiversity has been set aside.
We have seen that Lambro Park has 3 times the abundance of pollinators of City Life and 23 times that of Milan's Duomo. Obviously the figure is similar for the site's Nectariferous Potential, which for Lambro Park is about 3 times that of City life and 30 times that of the Duomo area.
These data confirm that purely concrete areas tend to exclude biodiversity. By strategically reintegrating greenery within urban areas, these values clearly improve: this is the case of City Life, which, although it may have lower values than the Park, has far higher values than the Duomo area.

In light of these findings, we can say that urgent action is needed. But what can be the best practices to make our cities more habitable by pollinators? The first step is the regeneration of certain areas, integrating greenery in a strategic and targeted manner, inserting native species suitable for this purpose. An underestimated aspect is the correct management of greenery: mowed lawns may be aesthetically pleasing, but they are not helpful. Reducing the mowing of greenery in cities can lead to greater availability of food and nesting sites for pollinators. Municipal authorities can not only take the lead in these initiatives, but also set guidelines for private management. This two-pronged approach is the right one to allow pollinators to coexist with us, in our cities, and is the one adopted by 3Bee, which proposes concrete solutions in this context.