The experimental project “Climate-friendly Parks”: evaluation of ecosystem services in urban micro-forests at Reggio Emilia (Italy)

Overurbanization is causing environmental issues that threaten human health and biodiversity in increasingly crowded cities. Urban green infrastructures are crucial for enhancing urban livability, restoring biodiversity, and providing numerous ecosystem services. This study evaluates the ecosystem services (ES) of an experimental urban greening project in "Marco Biagi" park in Reggio Emilia (Italy), as a part of the European Project Life CityAdap3. The municipality of Reggio Emilia planted several species between late 2021 and early 2022, covering a total of 8,76 m². The species were organized into two different micro-forests: - a native micro-forest, composed only of native species, characteristics of the woods of Po plain, that is the geographical area of reference; - an adaptative micro-forest where many species of the Mediterranean area were planted, being more suitable for future climatic conditions. Micro-forests have been realized according with the “Miyawaki method”, which involves a very high-density pattern (2-7 plants/m2, for a total of 450 individuals each), thus trying to simulate natural processes of ecological succession, from pioneer species to climax vegetation. Moreover, the rural edges, various tree rows, and a wetland area were realized in 2023, where several hydrophytes have been planted. The present research reports data of the first year of environmental monitoring and ES evaluation, starting from February 2024. Biodiversity assessment was performed on the two micro-forests and around the wet area; microclimatic mitigation effects of the green area were evaluated through the analysis of air temperature, air relative humidity, soil temperature, and soil water content. After 2 years from plantation, we have found a total of 772 individuals, differentiated into 72 different species. The Shannon-Wiener biodiversity index was computed, resulting in H’ = 3.44 with an evenness of J’ = 0.80; the biological spectrum, composed primarily of P scap and P caesp (around 64% of the total), reflects the predominance of the arboreal component of micro-forests. In general, we found that shrubs had a higher mortality rate compared to trees. iTree model has been applied to estimate carbon storage to find out which species have a greater carbon sink capacity, using allometric data (plants heigh and DBH measured on each individual). The total of trees in Marco Biagi park are estimated to store 0,332 metric tons of carbon, where Fraxinus excelsior and Quercus robur being the most efficient species (approximately 44.4% of the total carbon stored). Eco-physiological responses to heat stress during summer period were analyzed on two representative species of each micro-forest type (Quercus ilex and Quercus frainetto for adaptative forest; Carpinus betulus and Fraxinus excelsior for native forest). Stomatal conductance (gs) was analyzed through porometer and the emission of biogenic volatile organic compounds (BVOCs) were extracted from leaves and then determined through gas chromatography coupled with mass spectrometer. Data collected on the first year of environmental monitoring show that the different species are able to respond to environmental conditions, providing interesting and useful data about the environmental quality improvement of the area, especially according to the biodiversity and microclimatic mitigation.