Advancing Urban and Extra-Urban Afforestation: A Case Study of the Italian National Urban Forestry Plan in the Metropolitan City of Genoa

Abstract

Urban afforestation is a key strategy for combating climate change and enhancing urban living by reducing carbon emissions and improving air quality. Reflecting these priorities, Italy’s National Ecological Transition Plan (NETP), led by the Ministry of Ecological Transition (MiTE), introduced the National Urban Forestry Plan to accelerate sustainability and resilience in urban areas. This plan focuses on reducing carbon emissions, enhancing natural capital through reforestation, and promoting Nature-Based Solutions (NBS) for climate adaptation. Our study aligns with this framework by exploring how local urban forestry initiatives support the NETP’s objectives, providing a concrete example of policy implementation. Genoa (Italy) serves as a compelling case study. In 2023, the city received PNRR funding under the “Protection and Enhancement of Urban and Extra-Urban Greenery” initiative to improve air quality, restore biodiversity, and strengthen ecological corridors. Our research identifies three key areas for improvement: ecological planning, citizen engagement, and impact monitoring. We present initial findings and quantitative data, evaluating CO₂ sequestration potential, communication strategies, and consider the strengths and weaknesses of the specific context. These findings highlight the need for further investigation to optimize and communicate urban greening efforts.

1. Introduction

Nature-based solutions play a vital role in reducing carbon emissions and enhancing carbon sequestration, significantly contributing to achieving climate adaptation objectives. These solutions encompass reforestation, afforestation, and the conservation of forests, wetlands, coastal habitats, and grasslands. Forests are among the most effective carbon sinks [1]. Urban forests represent a complex system that includes forests, groups of trees, street trees, and individual trees situated in urban and peri-urban areas.

According to the FAO Guidelines on Urban and Peri-Urban Forestry [2], urban forests are considered the “backbone” of Green Infrastructure (GI), which is defined as a “strategically planned and managed network of natural land, landscapes, and other open spaces that protect the values and functions of ecosystems while providing a wide range of benefits to human populations and wild nature” [3]. Urban forests (UF) serve as a critical connection between rural and urban areas, significantly enhancing a city’s environmental sustainability by delivering essential ecosystem services and improving urban quality of life. Recognizing this, FAO has urged cities worldwide to invest in forest-based solutions to foster more sustainable and resilient urban development [4]. These initiatives not only address climate challenges but also support biodiversity, mitigate urban heat island effects, and contribute to public health and well-being, underscoring the multifaceted benefits of integrating urban forestry into strategic planning.

Urban forests significantly contribute to atmospheric purification by absorbing gaseous pollutants such as ozone, nitrogen oxides, and sulfur chlorides, intercepting particulate matter—including dust, ash, pollen, and smoke—and releasing oxygen via photosynthesis. Additionally, trees play a pivotal role in mitigating urban heat through shading and transpiration processes, which, in turn, can suppress ozone formation. Beyond these ecological functions, urban forestry is critical for carbon sequestration, energy demand reduction, and the promotion of sustainable urban development frameworks [5]. Urban forestry also facilitates essential ecosystem services such as carbon storage, erosion control, landslide risk mitigation, and biodiversity conservation. These functions align closely with international climate objectives, enabling local governments to adopt localized, bottom-up strategies that contribute to global sustainability targets [6,7].

Urban areas account for over two-thirds of global energy consumption and generate more than 70% of greenhouse gas (GHG) emissions, making afforestation a critical strategy for combating climate change in these settings [8]. Evidence suggests that increasing urban tree canopy cover can reduce summer temperatures by up to 3 °C, thereby lowering peak ozone levels and improving air quality [9]. Urban afforestation is therefore a pivotal strategy for mitigating climate change and improving urban living conditions. It contributes directly to the decarbonization of metropolitan areas and aligns with the objectives of the Paris Agreement. As urban populations continue to expand, the integration of urban forestry into climate strategies becomes increasingly essential for fostering resilient and sustainable urban environments capable of both adapting to and mitigating the impacts of climate change.

Municipalities play a central role in the effective implementation of urban forestry as part of climate mitigation efforts. Sustainable Energy and Climate Action Plans (SECAPs) frequently incorporate urban forestry as a key component of broader initiatives aimed at reducing carbon footprints and meeting climate objectives. The strategic inclusion of urban forestry into municipal planning and execution is critical for achieving long-term decarbonization goals. By facilitating these efforts, local governments contribute significantly to the broader global commitment to addressing climate change through scientifically informed, localized action [10].

UF, which include all trees within urban realms such as parks, streets, private properties, and greenways, play a critical role in carbon sequestration. Forests act as a temporary carbon sink, delaying the release of stored carbon until the wood is harvested and reintroduced into the carbon cycle. This process helps offset emissions from urban activities, particularly in cities, where transportation, industry, and energy production are major sources of greenhouse gases [11]. Despite growing public interest in urban forestry, its role in climate mitigation has received comparatively less scientific attention than rural reforestation studies [12].

According to literature, urban forestry demonstrates a lower climate mitigation potential—estimated at 82.4 ± 25.7 MtCO₂ per year—compared to rural reforestation, which sequesters approximately 1600 MtCO₂ per year. Nevertheless, UF can offset more than 25% of carbon emissions within city boundaries, making it a vital strategy for local-level climate change mitigation [12]. Urban forests currently cover approximately 6.0 ± 1.5 million hectares globally, representing 9.7% of total urban areas, with estimates suggesting that 100,000 urban trees can sequester around one million tons of CO₂ [13].

UF, parks, and street trees are particularly effective for carbon sequestration due to their high woody biomass. However, their sequestration capacity varies widely, influenced by factors such as biome type, plant species, biophysical parameters, location, climate, and maintenance requirements [14,15]. To optimize carbon sequestration in urban areas, strategies include the protection, rehabilitation, or creation of green spaces and the introduction of vegetation with high carbon storage potential. Overall, the global implementation of urban vegetation strategies could improve annual carbon sequestration by 0.1 to 0.3 GtCO₂, highlighting their significant potential for supporting climate mitigation targets [16]. Heavily urbanized areas exhibit the highest emissions per unit area (57.95 kg CO₂e/m²), followed by suburban areas (7.99 kg CO₂e/m²), whereas afforested areas emit the least (0.73 kg CO₂e/m²) [7]. Expanding green spaces, particularly on brownfields, presents an opportunity to enhance carbon sequestration while simultaneously delivering additional ecosystem services.

In addition to direct carbon sequestration, afforestation contributes indirectly to decarbonization by reducing energy consumption. Urban trees provide shade, mitigate the urban heat island (UHI) effect, and lower ambient temperatures, which in turn decreases the demand for air conditioning. This natural cooling effect reduces energy use and the associated greenhouse gas emissions from power plants. Furthermore, energy cost savings are realized through the combined effects of shading, evapotranspiration, and wind speed regulation, which help conserve energy in buildings. Urban green spaces also encourage active transportation, such as walking and cycling, reducing dependency on motorized vehicles and thereby contributing to lower emissions. This shift not only supports decarbonization but also aligns with broader sustainability goals by improving public health and reducing air pollution [17].

In alignment with international commitments, the European Union has introduced the European Green Deal, aiming to achieve net-zero emissions by 2050 and a 55% reduction in emissions by 2030. Complementing the Green Deal is the Next Generation EU initiative, developed to stimulate economic recovery following the COVID-19 pandemic. This program operates through two primary mechanisms: the Recovery and Resilience Facility, which mandates member states to submit detailed plans for investments and reforms, and the REACT-EU package, which provides recovery assistance to support cohesion and regional development across Europe.

Given the growing political interest and significant public investment in Nature-Based Solutions (NBS) in Italy, the National Urban Forestry Plan has been introduced as a strategic framework for sustainable urban development. Italy’s national policies, including the National Ecological Transition Plan (NETP), emphasize the enhancement of natural capital and the expansion of urban green networks. Spearheaded by the Ministry of Ecological Transition (MiTE), the NETP provides a comprehensive approach to fostering urban resilience, with key objectives such as reducing carbon emissions, increasing green infrastructure, and promoting NBS for climate adaptation.

Our study aligns with this framework by examining how local urban forestry initiatives support the NETP’s strategic goals, demonstrating how national policies translate into tangible, city-level actions.

2. Materials and Methods

Urban forestry plays a crucial role in climate change mitigation and adaptation, particularly in Mediterranean cities, where rising temperatures and extreme heat events are increasingly frequent. Vegetation cover significantly influences urban microclimates, reducing urban heat island (UHI) effects through evapotranspiration, shading, and surface cooling. This relationship is particularly relevant in coastal cities like Genoa, where urban density, topography, and meteorological conditions contribute to temperature amplification, exacerbating thermal discomfort and energy demand for cooling. The success of urban reforestation initiatives relies on the careful selection of tree species adapted to urban microclimates and a comprehensive understanding of their ecological physiology. Addressing the specific environmental challenges of urban areas enhances the effectiveness of reforestation efforts, making significant contributions to climate change mitigation and urban resilience.

Genoa was selected as a case study due to its specific conditions, dense urban fabric, and ongoing urban greening initiatives, which together create an ideal setting to assess both the benefits and challenges of implementing nature-based solutions. Local authorities have been actively incorporating urban greenery into city planning to enhance ecosystem services, such as air quality improvement, temperature regulation, and biodiversity conservation. Despite spatial limitations and challenging topography, the city has pioneered urban forestry projects, including reforestation efforts, green corridors, and the revitalization of underutilized areas.

Due to the ongoing nature of the urban afforestation projects in Genoa and the limited availability of detailed implementation data from local authorities, this study adopted a mixed-methods approach based on policy analysis, literature review, and preliminary quantitative estimates.

First, we conducted a policy coherence analysis by comparing the urban reforestation projects currently underway in Genoa with the directives and strategic goals outlined by the National Urban and Peri-Urban Forestry Plan, as defined by Italy’s Ministry of Ecological Transition (MiTE). The analysis assessed compliance according to key criteria derived from national guidelines, including: (1) targeted increase in tree canopy cover; (2) contribution to ecological connectivity and biodiversity; (3) prioritization of native species adapted to urban and peri-urban environments; and (4) alignment with Nature-Based Solutions (NBS) principles aimed at climate adaptation and resilience.

Second, to quantify the potential carbon sequestration of urban forestry initiatives, we estimated the CO₂ capture capacity based on species-specific carbon sequestration rates derived from existing scientific literature and market values recognized internationally (e.g., IPCC guidelines, scientific publications, and forestry databases). We considered predominant species selected for afforestation in Genoa, incorporating tree growth rates, lifespan, and climatic suitability for Mediterranean urban environments.

Third, we evaluated the strengths and weaknesses of urban afforestation specific context, explicitly addressing the challenge posed by Genoa’s dense urban fabric, steep topography, and limited availability of space within urban boundaries. Given these constraints, reforestation initiatives were primarily implemented in peri-urban zones.

Given the preliminary stage of the projects analyzed, our evaluation primarily focused on verifying compliance with certain ecological criteria explicitly set by the National Urban and Peri-Urban Forestry Plan, such as the use of native species, species diversity, and structural composition of urban forests (proportion of shrubs to trees). Due to the lack of finalized quantitative data from ongoing projects, we performed a qualitative assessment based on available documentation, administrative reports, and literature-based estimations.

The evaluation criteria include: ecological benefits (e.g., biodiversity conservation, habitat restoration, climate regulation); socio-economic factors (e.g., recreational opportunities, public acceptance, aesthetic improvement); implementation feasibility (availability of land, maintenance requirements, adaptability of selected tree species); and potential drawbacks such as limited accessibility by citizens, higher costs of maintenance due to remote locations, and delayed impacts on urban microclimates.

The data sources utilized in this study included official documents and reports from national and local authorities (e.g., MiTE, PNRR documentation), peer-reviewed scientific literature on urban forestry, and semi-structured interviews conducted with key stakeholders involved in urban greening initiatives in Genoa. Literature sources included policy analyses regarding urban forestry efforts across major Italian metropolitan cities (e.g., Milan, Rome, Bologna, Turin), providing a comparative framework for interpreting Genoa’s initiatives.

The methodological framework of this study was developed within the PRIN2022 project “Better Policy” (Building Environmental Tools To Empower Responsive Policies Outreaching LIfeCYcle: Guidelines and protocols to enable Public Administrations-driven processes in the Italian construction sector), coordinated by the author and focused on decarbonization strategies within public administration processes. Although primarily concerned with reducing emissions in the construction sector, exploring complementary strategies such as urban reforestation was deemed relevant given the broader climate resilience objectives of the project.

3. Results

3.1. National Urban and Peri-Urban Forestry Plan

Recently, there has been a growing nationwide interest in urban reforestation to counteract the effects of climate change and enhance biodiversity [18,19,20,21]. Several major Italian metropolitan cities have initiated significant urban forestry projects, including Milan (“ForestaMi” project), Turin, Rome (“Roma Resiliente” plan), Bologna (“Città 30 e Verde” project), Florence, Naples, Bari, and Catania.

In Italy, climate and ecological transition policies are shaped by a comprehensive framework that includes the National Climate Change Adaptation Strategy (SNAC) and its implementation plan, the National Climate Change Adaptation Plan (PNACC). Additional guiding policies include the National Sustainable Development Strategy (SNSvS), the National Biodiversity Strategy, the National Integrated Energy and Climate Plan 2030 (PNIEC), which outlines decarbonization objectives, the long-term Italian strategy for greenhouse gas emissions reduction, and the National Air Pollution Control Program (PNCIA). The National Recovery and Resilience Plan (PNRR) serves as the main tool for achieving the objectives of political strategies. It defines Mission 2—Green Revolution and Ecological Transition, Component 4—Protection of Land and Water Resources, with Investment 3.1 focusing on the protection and enhancement of urban and extra-urban green areas. The PNRR project for Investment 3.1 designates Metropolitan Cities as the implementing bodies responsible for planning and executing interventions under an Urban and Peri-Urban Forestry Plan. The Italian Government, through the Ministry of Ecological Transition (MiTE), has established the National Urban and Peri-Urban Forestry Plan, aligned with the broader objectives of the PNRR [22]. This plan outlines the planting of 6.6 million trees, aiming to develop urban and peri-urban forests across the 14 largest metropolitan areas, restoring degraded habitats, and reconnecting ecological corridors in urbanized contexts. Metropolitan areas, as key centers of human activity, face significant environmental challenges, including high levels of air pollution and the Urban Heat Island effect due to extensive land use and multiple pollution sources (e.g., vehicular traffic, industrial activities, heating). These pollutants negatively impact human health and impose economic costs on society through environmental and health damages. Urban areas also contribute substantially to global warming by emitting GHG. In Italy, 3.3% of the urban population lives in areas exceeding European air quality limits, prompting the European Commission to initiate infringement procedures related to PM2.5, PM10, nitrogen dioxide, and non-compliance with Directive 2016/2284 on national emission reductions [23].

Resources allocation is based on environmental and social criteria, such as air quality and areas subject to infringement procedures. The plan provides a standardized methodology for selecting appropriate tree species suited to local ecological conditions. MiTE established a Steering Committee to ensure effective implementation to oversee operations, provide scientific support, and monitor impacts. The plan emphasizes using local native plants to avoid biodiversity loss while enhancing ecosystem resilience [23]. In terms of cooling effects, peri-urban forests can reduce summer temperatures up to 170 m from their edge, extensive urban forests up to 100 m, and roadside trees up to 30 m [23].

Vegetation types were evaluated based on their ability to absorb CO₂, remove atmospheric particulate matter (PM10), and mitigate the Urban Heat Island (UHI) effect. A study of 10 Italian metropolitan cities found that 1 hectare of urban forest removes approximately 17 kg/year of PM10, valued at EUR 1825, with a total estimated value of EUR 1.532 billion across the cities. Given the European Union Emissions Trading System (EU ETS) carbon price of EUR 100.34 per metric ton as of February 2023, the monetary value of CO₂ absorbed by Italian forests over the first five years can be calculated. Assuming an average absorption rate of 20 to 30 tons per hectare over five years, the estimated value ranges from EUR 2006.80 to EUR 3010.20 per hectare.

Deciduous broadleaf species have demonstrated superior capacities for atmospheric pollutant removal, including CO₂ sequestration (3,953,280 g/m²/year), O₃ absorption (5677.76 g/m²/year), and NO₂ uptake (2358.30 g/m²/year). Additionally, several species with exceptional carbon sequestration capacities have been identified, reaching up to 1025.47 g CO₂/m²/year in species such as Celtis australis, Platanus × acerifolia, Ulmus pumila, and Quercus rubra [24]. On a per-tree basis, it is estimated that a single tree can absorb carbon dioxide at an average rate of 21.8 kg/year, underscoring the cumulative impact of widespread urban reforestation. In the Mediterranean region, Pinus pinea has been identified as a species with the highest potential for carbon absorption and storage. This naturalized archeophyte species, while not spontaneously occurring, has shown significant promise in urban forestry programs tailored to the local environment [25].

According to the plan, evergreen broad-leaved trees and Mediterranean conifers are the most effective for CO₂ sequestration and PM10 removal (

Table 1. Quantitative and monetary evaluation of CO₂ absorption through the planting of different tree species according to Urban and Peri-Urban Forestry Plan. Adapted from: https:/mase.gov.it/ accessed on 16 December 2024.

Functional Type of Vegetation	Average CO2 Absorption (t/ha/yr)	CO2 Absorption First 5 Years (t/ha)	Lower Monetary Value of CO2 Absorbed First 5 Years (EUR/ha)	Higher Monetary Value of CO2 Absorbed First 5 Years (EUR/ha)	CO2 Absorption at 20 Years (t/ha)	Lower Monetary Value of CO2 Absorbed First 20 Years (EUR/ha)	Higher Monetary Value of CO2 Absorbed First 20 Years (EUR/ha)
Deciduous broadleaf	6.6	21.9	208.2	835.2	121.6	1154.8	4631.5
Evergreen broadleaf	9.5	31.5	299.1	1199.7	174.6	1658.9	6653.0
Mediterranean conifers	9.0	29.7	281.9	1130.5	164.5	1563.2	6269.1
Mountain conifers	5.7	18.7	177.2	710.6	103.4	982.6	3940.6

). While assessments currently show variability, more precise data will be available with advanced planning.

To maintain structural efficiency and ecosystem functionality, it is required to plant species that are suited to the local environment and consistent with the area’s natural vegetation. Effective reforestation necessitates the use of plant material specifically adapted to the microclimatic and soil conditions of each locality. A recent detailed review of nurseries in Sicily and Apulia indicates that these facilities are capable of producing high-quality, locally adapted plants with strong potential to withstand the effects of climate change [26]. This approach is critical for preserving biodiversity, safeguarding endangered species, and preventing genetic pollution. Forest nurseries are integral to this process, as they provide seedlings derived from native seeds, ensuring ecological compatibility and resilience. However, recent Italian regional forestry policies have largely overlooked nursery activities, resulting in a decline in both regional nurseries and skilled personnel. This has constrained the availability of high-quality native plant material. Hence, the success of this ambitious initiative is contingent upon a substantial supply of native trees and shrubs, which are currently underproduced in Italian nurseries. Despite this, the quantity of plant material remains insufficient to meet the increasing demand driven by contemporary green policies [26].

To assist Metropolitan Cities in identifying suitable reforestation areas, summary maps of potential vegetation based on the Vegetation Series of Italy mapping were provided in the Plan. These maps, which outline the mature stage of vegetation for each series, are intended as a general guide to promote more detailed studies that consider local soil, vegetation, and climate conditions. A recommended list of trees and shrubs serves as a basic guide for experts, who may also select additional species that align with the biogeographical and ecological context. The list integrates evergreen and deciduous species to maximize CO₂ storage and particulate matter removal throughout the year. It also includes species tolerant of high temperatures, promoting adaptation to climate change. Overall, a high level of biodiversity is recommended to ensure the resilience and robustness of reforestation efforts.

The following section analyzes the case of the Metropolitan City of Genoa, selected for its proximity, access to data on an ongoing reforestation project, and collaboration with local experts.

3.2. The Case of Genoa, Italy

Genoa was selected as a case study due to its combination of Mediterranean climatic conditions, dense urban fabric, and ongoing urban greening initiatives. These factors create an ideal setting for assessing the efficacy and challenges of implementing nature-based solutions (NBS) in mitigating extreme heat effects. Despite spatial constraints and complex topography, Genoa’s urban forestry initiatives—including reforestation efforts, green corridors, and revitalization of underutilized spaces—demonstrate the potential of nature-based interventions in enhancing urban climate resilience.

The city is wedged between the Ligurian Sea and the Apennine mountains, resulting in urban districts that climb steep hillsides. The average slope gradient in parts of Genoa reaches about 50%, with peaks up to 70–75% incline on the surrounding hills [27]. This steep terrain poses obvious challenges for afforestation. Planting trees on very steep slopes is technically difficult—access for planting and maintenance is hard, soil tends to be shallow and prone to drying, and gravity can cause newly planted saplings (and soil amendments) to wash downhill during heavy rain.

The Metropolitan City of Genoa spans 183,375 hectares, with 12% designated as agricultural land and 8% as built-up areas. The landscape of Genoa is marked by a clear contrast between the densely built-up coastal and valley areas, which have minimal greenery, and the rest of the municipality, dominated by forests, shrublands, and abandoned fields, though transitional zones emerge along the hills and riverbeds where urban and natural elements intermingle. Forested and semi-natural areas cover 80% of the total municipal territory, the highest percentage of such land cover among Italy’s metropolitan cities. These areas are primarily characterized by deciduous broadleaf forests, such as chestnut and beech woods, which play a crucial ecological and cultural role. Advances in remote sensing technologies have significantly improved the ability to study and manage these ecosystems. Metrics such as the Leaf Area Index (LAI) and phenological indicators provide valuable data for ecological research, urban green infrastructure planning, and the refinement of models assessing the ecosystem services offered by urban vegetation. In Genoa, the dominance of forested and semi-natural areas is particularly evident in their contribution to seasonal patterns in LAI. During summer, the dense canopy structure is reflected in high average (4.47) and maximum (6.37) LAI values. These values drop sharply in winter to an average of 0.77 and a maximum of 3.93, underscoring the deciduous nature of the predominant vegetation. This pronounced seasonal variation highlights the need to incorporate temporal dynamics into ecosystem assessments, enhancing our understanding and management of these landscapes.

Despite its high forest cover, air quality suffers from the negative effects of port activities. Recent monitoring data highlight that Genoa’s geographical setting as a coastal city with a busy port significantly influences its air quality. According to ARPAL, Urban PM10 concentrations average around 30 μg/m³—near or slightly above the EU annual limit of 25 μg/m³—with particularly elevated levels recorded in areas adjacent to the port. Moreover, NO₂ measurements in the port vicinity average approximately 50 μg/m³ [28], with episodic peaks coinciding with high shipping activity, clearly indicating the substantial contribution of port operations to local air pollution. Elevated levels of black carbon further corroborate the impact of combustion-related emissions from maritime traffic on Genoa’s air quality, underscoring the need for targeted mitigation strategies.

Genoa’s climate is Mediterranean but highly variable and locally intense—this adds another layer of challenge for urban forestry. On the one hand, the city enjoys mild, wet winters and hot, dry summers typical of its region. On the other hand, the Ligurian coast is infamous for sudden severe storms. Liguria (and Genoa in particular) is characterized by short but intense rainfall events that can drop huge volumes of water in just a few hours [29]. These cloudbursts regularly cause flash floods and severe runoff down the steep streets. For newly planted trees or forested slopes, heavy rain can mean soil erosion around roots, seedlings getting washed out, or even debris flows taking out vegetation. Afforestation projects must therefore include erosion control—for example, using mulch, geotextiles, or terracing to protect young plantings until they are established.

In 2024, temperatures exhibited frequent fluctuations. The coolest values, occasionally dropping below historical minimums for the period, were observed at the end of April, in June, and mid-September. Conversely, the warmest values, nearing historical maximums, occurred between mid-January and March, early July to mid-August, as well as in October and December. The annual average temperature was approximately 16 °C. During July and August, average minimum temperatures ranged between +20.8 °C and +20.9 °C, while average maximum temperatures varied from +27.2 °C to +27.5 °C. High humidity levels, particularly at night, often resulted in a pronounced feeling of mugginess, even when temperatures were not exceptionally high [28].

The Mediterranean region is experiencing a notable intensification of heat waves, with rising nighttime temperatures and extreme daytime peaks (Figure 1). During the summer of 2024, particularly in late July, Genoa endured prolonged extreme heat, with temperatures exceeding 35 °C and locally approaching 40 °C, accompanied by high humidity levels (Figure 2a,b). This follows an alarming trend, with an increasing frequency of “tropical nights”—when nighttime temperatures fail to drop below 28–30 °C. The situation is further underscored by record-breaking heat events in 2023, including Liguria’s first-ever coastal 40 °C, recorded at Rapallo (GE) on 21 August 2023, with a peak of 40.6 °C. Inland areas experienced even more extreme conditions, with temperatures reaching 41–42 °C.

Three key factors are driving these temperature anomalies:

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Exceptionally Warm Sea Surface Temperatures (SSTs)—The Ligurian Sea’s surface temperatures have reached unprecedented levels, locally approaching 29 °C, reducing the thermal contrast between sea and land. This has diminished the cooling effect of sea breezes, intensifying coastal heat stress.

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Elevated 850 hPa Isotherm Temperatures—Atmospheric temperatures at ~1500 m altitude have been recorded at +20/22 °C, typically corresponding to surface temperatures of 36–38 °C. While Liguria’s complex topography and sea influence historically moderated these effects, the mitigating mechanisms appear to be weakening.

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Föhn Winds and Adiabatic Compression—Under certain meteorological conditions, downslope föhn winds descending from Liguria’s mountain ranges accelerate warming through adiabatic compression, causing temperature spikes from early morning hours, compounding extreme heat conditions.

Given these climatic trends, the implementation of urban forestry strategies in Genoa is particularly urgent. Increasing urban vegetation can help counteract rising temperatures by:

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Reducing surface and air temperatures through evapotranspiration and shade provision;

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Mitigating urban heat island effects, particularly in densely built environments;

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Improving thermal comfort by enhancing wind circulation and reducing heat retention in urban materials.

The Municipality received PNRR funding titled “Protection and Enhancement of Urban and Extra-Urban Greenery” in 2023. The grant funding for afforestation projects originates from the national strategy outlined in the Urban and Peri-Urban Forestry Plan [23]. The funded projects that have been executed include three main projects: “Genoa Verde”, “Extra-urban Afforestation”, and “Genoa and Eastern Genoese”. These projects highlight a commitment to the sustainable and resilient management of urban and peri-urban green areas with objectives for environmental improvement and climate change adaptation (

Table 2. List of ongoing projects in the Metropolitan City of Genoa. Source: Metropolitan City of Genoa.

Project	Location	Description	Status	Duration	Final Target	Total Cost(EUR)
“Genoa Verde” (code MASE GE01)	Genoa, Scarpino area (where the city’s main landfill is located)	Urban and peri-urban afforestation to stabilize soil, increase biodiversity, restore degraded areas and CO2 sequestration	Intervention completed and under maintenance	Start Date: 8 May 2022 End Date: 31 March 2026	30 hectares 30,000 plants	1,291,156.52
“Extra-urban Afforestation” (code MASE GE02)	Arenzano, Bric Bardella Punta Goetta Cogoleto, Prato Zanino Ronco Scrivia	Planting in riparian zones to improve biodiversity, supporting the ecological resilience of areas not covered by Natura 2000	To be completed by the end of 2023 with planting, work inspection, and start of maintenance	Start Date: 8 May 2022 End Date: 31 March 2026	40 hectares 40,000 plants	1,728,882.20
“Genoa and Eastern Genoese” (code MASE GE01-2023)	Bogliasco, Genoa, Pieve Ligure	The project aims to increase forest cover and improve biodiversity and the ecological functionality of ecosystems in these areas	Finalization of project. To be completed by the end of 2024	Start Date: 31 January 2024 End Date: 30 June 2026	40 hectares 40,000 plants	1,726,267.06

).

Based on the analyses carried out during the preparation phase of the Plan, resources were allocated specifying the targets (hectares/number of plants) for each Metropolitan City.

Recent studies emphasize the importance of prioritizing tree planting in urban areas and along linear infrastructures, as these locations offer significant opportunities to integrate vegetation into human-dominated landscapes. Furthermore, they argue that afforestation efforts yield the greatest biodiversity benefits when focused on degraded lands. This approach not only supports ecological restoration but also reduces the pressure to afforest wild open areas, thereby helping to conserve their natural ecosystems and maintain biodiversity [30]. In this case, the selected areas include degraded former industrial areas, riparian zones, and open fields upon the hills. The selection of areas for the afforestation projects was made in collaboration with the metropolitan municipalities.

3.3. Afforestation Projects in the Metropolitan City of Genoa: Plant Choice

The initial project sheets approved by the Ministry do not explicitly mention a detailed calculation of CO₂ absorption during the growth of the plants in the afforestation projects. However, they discuss the overall positive impacts on the environment and air quality through the reduction of greenhouse gases and the increase in vegetation cover, particularly using evergreen species that can absorb CO₂ more effectively.

Recent studies demonstrated that a newly planted urban forest in Southern Europe requires 13 years to function as an effective carbon sink; results indicated that 7–8 years are required for canopy development to offset carbon emissions from soil and other sources, with full carbon neutrality achieved after 13 years [31]. The exponential increase in CO₂ removal capacity beyond this point aligns with similar findings [32]. Tree biodiversity was found to play a decisive role in enhancing CO₂ sequestration. The selection of tree species should prioritize a mix of evergreen and deciduous species to ensure year-round CO₂ assimilation. For example, evergreen species like Cupressus sempervirens act as carbon sinks during winter, while deciduous species such as those from the Tilia and Ulmus genera exhibit higher photosynthetic rates during the growing season. Incorporating CO₂ sequestration potential as a criterion for species selection maximizes the ecological benefits of urban forests. Several abiotic stresses, including drought, nutrient deficiency, and pollution, could constrain CO₂ assimilation in urban environments. For instance, prolonged droughts typical of Mediterranean climates may cause trees to close stomata to conserve water, thereby reducing carbon uptake. Optimal tree density (309 trees/ha), was near the saturation threshold, ensuring efficient carbon sequestration without delays in the offset timeline [33].

The selection of native species for reforestation efforts is critical. However, climate change poses a substantial challenge, as native species and ecotypes may no longer be optimally adapted to current or future climatic conditions. For example, southern ecotypes may already exhibit greater adaptability in northern regions, where heatwaves and prolonged droughts are becoming increasingly frequent and severe. The evolutionary potential of many European tree species could be undermined if genotypes and ecotypes are mixed without careful consideration of the characteristics of local populations [30].

In all three projects, the emphasis on the selection of native species was required to ensure the resilience and environmental integration of the new plantations, as well as to improve the biodiversity and ecological stability of the areas involved (see

Table 3. List of Selected Plant Species for the implemented projects in the Metropolitan City of Genoa. Source: Metropolitan City of Genoa.

Project	Tree Species	Shrub Species	Use of Native Plants
Genova Verde	Quercus ilex Quercus pubescent Ostrya carpinifolia Prunus avium Fraxinus ornus Alnus glutinosa.	Erica arborea Prunus spinosa Juniperus communis Sorbus torminalis Cistus salviifolius Cytisus scoparius Rhamnus alaternus	The goal was to use native plants to support local resilience and biodiversity.
Extra-urban Afforestation	Acer campestre Alnus glutinosa Fraxinus ornus Ostrya carpinifolia Populus alba Populus nigra Quercus ilex Quercus pubescens Salix alba	Arbutus unedo Cistus salviifolius Cornus sanguinea Crataegus monogyna Myrtus communis Pistacia lentiscus Salix purpurea, Prunus spinosa, Rhamnus alaternus Rosa sempervirens Viburnum lantana Viburnum tinus	Native species only, maintaining a ratio of 70% trees and 30% shrubs consistent with the potential natural vegetation of the area, to preserve and enhance ecological coherence with the local environment.
Genoa and Eastern Genoese	various species including Quercus ilex, Fraxinus ornus	various species of Cistus and Thymus	Use of predominantly native plants to strengthen fire resistance and improve biodiversity in areas prone to clearings and gaps due to previous fires.

). The species were identified according to the criteria established by the Public Notice. Each reforestation intervention must provide for the planting of 1000 plants per hectare, with the presence of shrubs in a percentage ranging between 10 and 30%, chosen according to the successional dynamics of the potential natural vegetation and, when possible, referring to the species indicated for each metropolitan city in the Plan. The forest propagation material must consist of native species, and its procurement by the Metropolitan Cities must be ensured by nurseries that guarantee provenance certification.

Planting was planned for both trees and shrub species. The rules set by the Ministry require that plants, shrubs, or seeds have a well-specified provenance and certificates of origin. It was not required that they come from Ligurian nurseries. In fact, there are no regional forest nurseries in Liguria. For both realized projects, both seeds and plants were used, provided by nurseries identified by the two economic operators who won the work tenders. For the project “Genoa and Eastern Genoese”, since the project is in its initial phase, efforts are being made to obtain the entire range of plants needed through the agreements with certified nursery companies.

The PNRR Afforestation projects “Genoa Verde” and “Extra-Urban Afforestation” are advancing with work execution and on-site testing underway. The planting phase has been completed, and the mandatory five-year monitoring and maintenance plan has started. Meanwhile, the “Genoa and Eastern Genoese” project is in the executive design phase, preparing for tender documentation and subsequent implementation. These projects aim to enhance urban resilience and sustainability by improving air quality, increasing biodiversity with native species, sequestering carbon to mitigate climate change, managing hydrogeological risks, and enhancing overall well-being and quality of life. Despite initial challenges, such as meeting the December 2023 milestone and securing suitable land for afforestation, progress has been consistent. Activities now focus on ongoing maintenance, including plant health monitoring, replacement of dead plants, irrigation, and control of invasive vegetation, aiming to meet the planting targets by November 2024, with completion deadlines set for December 2024 and December 2025. Afforestation efforts extend beyond urban areas, influencing the urban microclimate, although a detailed climatic analysis was not explicitly required by the Ministry. The Metropolitan City is proceeding with its maintenance and monitoring phases for “Genoa Verde” and “Extra-Urban Afforestation”, while also moving forward with the planning and execution of the “Genoa and Eastern Genoese” project. These initiatives collectively represent a comprehensive strategy to enhance the resilience and ecological sustainability of the metropolitan area. During planting, forest plants have been marked with orange paint and/or shelters to help monitor their future growth. Monitoring and verification of planting are conducted using a drone for irregular, naturalistic spacing (Figure 3).

Key Aspects of Reforestation in Genoa include:

• Plant Density: Reforestation requires 1000 plants per hectare, with 10–30% shrubs based on successional dynamics of natural vegetation and recommended species.
• Using Native Species: The selection of native species emphasized resilience biodiversity, and ecological stability.
• Focus on evergreen broad-leaved trees and Mediterranean conifers, most effective for CO₂ sequestration and PM10 removal.
• Provenance Certification: Forest propagation material must consist of native species with certification of origin from approved nurseries.

The “Genova Verde” project focuses on targeted interventions across various areas of the metropolitan city of Genoa, aiming to enhance forest and environmental resources. In the Sestri Ponente area, located northwest near the Scarpino landfill, the forest parcels are characterized by mixed conifer and broadleaf forests interspersed with vegetation-free zones showing signs of surface erosion. The forest management plan includes measures to diversify and expand shrub and tree cover, employing species with strong biotechnical properties for soil stabilization. Additionally, the plan seeks to enhance biodiversity and increase the area’s attractiveness to birdlife.

As for the extra-urban reforestation efforts, two key areas stand out. The Cogoleto-Arenzano zone is marked by Mediterranean shrublands and bushy areas, shallow soils, and rocky terrains with sparse vegetation cover, along with clusters of maritime pine forests. The Ronco Scrivia area, on the other hand, features a riparian zone with the potential for poplar and willow groves, alongside former industrial zones with sandy and deep soils. Here, the primary goal is to establish a buffer zone to counterbalance urban settlements and infrastructure, while also creating recreational and sports areas along the river.

Finally, the potential natural vegetation communities in these areas include the Ligurian sub-acidophilous holm oak series (Viburno tini—Querco ilicis sigmetum) and the Ligurian edaphically indifferent downy oak series (Rubio—Querco pubescentis sigmetum), both of which are well-suited to local conditions and contribute to restoring ecological balance.

4. Discussions

Although our methodological framework identified comprehensive evaluation criteria (ecological benefits, socio-economic factors, and spatial constraints), due to the current status of urban forestry initiatives in Genoa, only preliminary qualitative assessments were possible. Specifically, our results confirmed adherence to national guidelines regarding native species selection and vegetation composition. However, quantitative assessments of socio-economic benefits or detailed ecological impacts (such as biodiversity restoration or long-term climate mitigation effects) are not yet available and will require systematic monitoring over time. Spatial constraints were qualitatively discussed, emphasizing the challenges of densely built environments that led to prioritizing peri-urban zones.

The projects, aligned with both national and European Union strategies, aim to enhance citizens’ quality of life and well-being through a series of reforestation, afforestation, and densification initiatives. These efforts address critical challenges such as air pollution, climate change mitigation, and biodiversity loss.

In particular, the initiatives adhere to modern environmental and urban planning policies that emphasize afforestation as a tool for promoting urban resilience and sustainability. The Metropolitan Municipality has set general objectives that reflect these priorities. First, the projects aim to improve air quality by leveraging the natural capacity of plants to absorb CO₂ and other air pollutants, thereby enhancing the atmosphere in urban and peri-urban areas. Another key objective is the increase of biodiversity, achieved by introducing a diverse range of native plant species to create and strengthen habitats for local flora and fauna. Additionally, the interventions contribute to climate change mitigation through carbon sequestration by the trees and shrubs planted. Vegetation also plays a critical role in responding to hydrogeological risks by stabilizing soil and managing rainwater runoff, thus mitigating erosion and flood risks. Finally, the creation of green spaces seeks to enhance urban well-being by offering psychological benefits and improving the quality of life. These spaces provide opportunities for rest and recreation, fostering a healthier and more connected local community.

Evergreen broad-leaved trees and Mediterranean conifers yield the highest returns and are also the most efficient in terms of particulate matter removal (see

Table 4. Quantitative and monetary evaluation of CO₂ absorption through the planting of different tree species. Adapted from: https://www.mase.gov.it, accessed on 20 Decembere 2024.

Functional Type of Vegetation	Average CO2 Absorption (t/ha/yr)	CO2 Absorption in the First 5 Years (t/ha)	Lower Monetary Value of CO2 Absorbed in the First 5 Years (EUR/ha)	Higher Monetary Value of CO2 Absorbed in the First 5 Years (EUR/ha)	CO2 Absorption at 20 Years (t/ha)	Lower Monetary Value of CO2 Absorbed in the First 20 Years (EUR/ha)	Higher Monetary Value of CO2 Absorbed in the First 20 Years (EUR/ha)
Deciduous broadleaf	6.6	21.9	208.2	835.2	121.6	1154.8	4631.5
Evergreen broadleaf	9.5	31.5	299.1	1199.7	174.6	1658.9	6653.0

).

Quantitative CO₂ evaluation aligns with IPCC guidelines and established scientific literature [34,35]. The estimated average CO₂ absorption rates of 6.6 tCO₂/ha/yr for deciduous broadleaf forests and 9.5 tCO₂/ha/yr for evergreen broadleaf forests are consistent with standard carbon density values and turnover rates. Given that the carbon stock for trees is 120 tC/ha, and applying a moderate turnover rate of 2.5% per year, the estimated annual carbon sequestration would be 3 tC/ha, translating to approximately 11 tCO₂/ha/yr (using the IPCC conversion factor of 3.67). These reported values fall within a plausible range, considering that deciduous forests experience seasonal biomass loss, whereas evergreen forests maintain more consistent carbon uptake. While these figures align with general scientific estimates, specific variations depend on forest type, age, and environmental conditions.

To enhance the robustness of the quantitative CO₂ sequestration assessment, it is essential to incorporate confidence intervals for these estimates. This will allow for a more precise evaluation of potential variations arising from environmental conditions, such as soil composition, climatic fluctuations, and species-specific growth dynamics. Additionally, scenario-based analyses should be conducted to account for uncertainties linked to land-use changes, forest management practices, and long-term climate trends.

By calculating the arithmetic average of the minimum ministerial estimates of total CO₂ absorption over 20 years for deciduous broadleaf forests (121.6 tCO₂/ha) and evergreen broadleaf forests (174.6 tCO₂/ha), an average value of 154 tCO₂/ha was obtained. Therefore, the total CO₂ absorption for 110 hectares of urban forestry interventions would amount to 16,940 tons, corresponding to a total monetary value of EUR 643,632 in the first 20 years. However, the economic valuation methodology requires further clarification, particularly regarding the assumptions underlying the monetary calculations.

Official estimates from ministerial sources indicate that the lower and higher monetary values of CO₂ absorbed in the first 20 years range between EUR 1154.8 and 4631.5 per hectare for deciduous broadleaf forests (assuming an absorption rate of 6.6 tCO₂/ha/year) and between EUR 1658.9 and 6653.0 per hectare for evergreen broadleaf forests (assuming an absorption rate of 9.5 tCO₂/ha/year). Based on these values, the implicit carbon price ranges between approximately 8.75 EUR/tCO₂ and 35.09 EUR/tCO₂ for deciduous broadleaf forests and between 8.75 EUR/tCO₂ and 35.02 EUR/tCO₂ for evergreen broadleaf forests. This implicit price range is considerably higher than the 6.11 EUR/tCO₂ reported in some literature sources [36], but remains below recent market prices for carbon credits, which have fluctuated between 58 EUR/tCO₂ and 102 EUR/tCO₂ in the past two years. This suggests that the ministerial estimates fall within a reasonable, albeit somewhat conservative, valuation framework. A more detailed discussion of the economic parameters used in the present analysis—such as carbon pricing mechanisms, inflation-adjusted valuation, and sensitivity to market fluctuations—would enhance the credibility and applicability of the monetary assessment. Given the wide range of values, it is recommended to incorporate updated market prices for carbon credits when assessing the financial benefits of CO₂ sequestration projects. Additionally, periodic recalibrations of economic models should be considered to reflect evolving market conditions.

Forestation has been successfully carried out in peri-urban areas following sustainable reforestation principles, respecting native vegetation series, and enhancing biodiversity. However, the specific impacts of these interventions on the urban environment remain unclear, particularly in relation to adjacent green spaces in densely populated areas. Effects such as the reduction of the urban heat island effect, improvement of air quality through atmospheric pollutant absorption, noise reduction, and the enhancement of residents’ psychophysical well-being require further study. Conducting additional research to better quantify and understand these potential benefits will be crucial in guiding future urban forestry policies toward interventions specifically tailored to the urban context. It is also worth noting the mitigation effect exerted by vegetation on the local climate, which is extremely important in an urban context characterized by the heat island effect. Research indicates that urban green spaces, including forests and roadside trees, can significantly mitigate surrounding temperatures, with the extent of this cooling effect varying based on the size and type of vegetation. Regarding urban forests, another study observed that the temperature within urban forests decreased by approximately 1.9 °C over a distance of ~3 km from the traffic island near the city to the forest, indicating a substantial cooling effect extending several kilometers [37].

Urban reforestation initiatives supported by the Italian Recovery and Resilience Plan represent an important opportunity to enhance urban environments and improve quality of life for future generations. However, the realization of these objectives is hindered by several obstacles. Limited spaces for reforestation in densely built urban areas, political inaction, and insufficient nursery stocks of native plants pose significant barriers. Addressing these issues requires enhanced inventory management, expanded production capacities, and greater investment in nursery infrastructure to ensure the successful implementation of reforestation strategies. The decision to focus reforestation efforts on peri-urban areas appears to be influenced by the characteristics of densely populated urban structures, where space for planting is limited. In urban centers, planting opportunities are constrained by small park sizes and partial private ownership of green spaces due to historical factors. Additionally, there has been limited integration of greenery within buildings, a situation exacerbated by stringent landscape protection regulations applied across large portions of urban areas.

Although afforestation offers multiple benefits, its capacity to absorb CO₂ remains limited when compared to the overall emissions produced by urban areas. This highlights the need to complement peri-urban interventions with targeted measures within urban boundaries, aiming to enhance the ecological performance of cities. At present, urban forestry projects are in the process of being completed, and therefore no documentation on their outcomes has yet been made public. However, it is interesting to analyze how different administrative bodies (municipalities, metropolitan cities, and regions) have chosen to communicate the ongoing processes. In most cases, official websites have published documents related to administrative procedures and calls for tenders for reporting the works. This approach aims to provide citizens with useful tools to understand the actions of public administrations, also in compliance with the necessity of transparency. However, the nature of such documentation makes it difficult to read for an audience that is not well-versed in legal-administrative matters. To address this, some institutions have included news articles or press kits on their official channels, designed to be picked up by newspapers and media outlets at both local and national levels. Among these, notable examples include the Municipality of Rome [38] and the Metropolitan City of Genoa [39], which has also produced a video to better inform citizens about the implementation of ongoing projects. Other institutions have included technical-scientific documentation to complement the information provided by the ministry. Among them, the Metropolitan City of Turin [40] has made a detailed list of project sheets accessible on its website, while the Metropolitan City of Bologna has added a series of attachments containing technical-scientific guidelines for metropolitan forestry [41].

In general, however, there is a certain inconsistency in the information and content published, particularly regarding public outreach communication as well as technical-scientific information, which is essential for ensuring greater involvement of the scientific community in the crucial phase of evaluating the objectives achieved and the results obtained.

5. Conclusions

This study evaluates the reforestation initiatives implemented in the metropolitan area of Genoa, focusing on their outcomes and challenges. Reforestation efforts in peri-urban areas have been executed adhering to sustainable principles, respecting native vegetation series, and enhancing local biodiversity. These initiatives are estimated to have an average carbon dioxide absorption capacity of 154 tons per hectare over 20 years. For the 110 hectares targeted by urban forestry interventions, the total anticipated CO₂ absorption amounts to approximately 16,940 tons, with a corresponding monetary valuation of EUR 643,632 for the carbon sequestered over the same period. Given the preliminary nature of this evaluation, detailed economic assessments should be addressed in future studies, incorporating comprehensive cost-benefit analyses based on finalized implementation data and updated market carbon prices.

Despite these positive outcomes, the specific impacts of these initiatives on key urban environmental factors remain uncertain. Afforestation efforts have the potential to influence the urban microclimate beyond the immediate area of intervention. However, detailed climatic analyses have not been required by local authorities. Moreover, forest nurseries have faced significant challenges in maintaining native biodiversity, often resorting to non-native genotypes whose adaptability to local conditions is uncertain. These challenges highlight critical gaps in the planning and implementation of reforestation efforts.

Qualitative considerations highlighted key strengths and limitations, particularly related to Genoa’s dense urban fabric and challenging topography. The primary strengths include enhanced ecological connectivity, improved biodiversity through the planting of native species, and potential contributions to mitigating urban heat islands and enhancing air quality. Conversely, significant limitations include limited citizen accessibility due to the peri-urban location of interventions, increased maintenance challenges posed by steep terrain, and insufficient integration of greenery within densely built urban areas. These findings suggest the necessity for complementary urban-scale interventions—such as microforests, pocket parks, and vertical greening—to effectively overcome spatial constraints and maximize ecological and socio-economic benefits.

Integrating greenery into urban areas as Genoa necessitates innovative, scientifically grounded approaches to address spatial constraints while maximizing ecological and environmental benefits. Regulatory constraints—from tight urban planning rules to heritage protections—require creative navigation and policy innovation, while the physical hurdles of steep, unstable terrain call for engineering savvy and adaptive planting techniques. Small-scale afforestation projects, such as microforests or the conversion of derelict urban lots into vegetated pocket parks, can enhance biodiversity and ecological stability. Vertical greening systems, such as modular green walls, could offer a viable solution for enhancing building envelopes, improving air quality, and mitigating the urban heat island effect. These systems can be designed with native or drought-tolerant species, ensuring low water consumption and ecological compatibility. Similarly, rooftop forests present a transformative potential by repurposing underutilized spaces into carbon-sequestering ecosystems. When integrated with photovoltaic systems, rooftop greenery can simultaneously optimize energy efficiency and urban sustainability. To ensure widespread adoption, urban planning regulations must mandate green infrastructure in new developments, supported by spatial analysis to identify optimal intervention sites.

The realization of these interventions depends on addressing key challenges in nursery capacity, native plant availability, and biodiversity conservation through robust policy measures. Expanding the production of high-quality, climate-resilient native plant species requires significant investment in nursery infrastructure and operations. Policy frameworks should establish certification programs to ensure that nurseries adhere to standards of biodiversity preservation and ecological suitability. Furthermore, fostering collaboration between nurseries and research institutions can enhance species selection and propagation techniques, prioritizing genotypes that are resilient to changing climatic conditions. A centralized database for plant stock and demand, integrated with a national monitoring system, could align nursery outputs with regional and municipal afforestation objectives. To maximize carbon sequestration and ecosystem services, reforestation strategies should employ a mix of evergreen and deciduous species, ensuring year-round functionality. Public-private partnerships and economic incentives, such as subsidies for nurseries employing sustainable practices, can bolster these efforts. Enhanced inventory management, coupled with region-specific species recommendations, will be critical for achieving long-term ecological sustainability and meeting national climate targets.

Further research is needed to quantify the impacts of peri-urban afforestation interventions, particularly in terms of their effectiveness in mitigating the urban heat island effect and improving air quality through pollutant absorption. Given the diverse environmental conditions of urban areas, each city must develop tailored solutions that align with its specific territorial characteristics. In this regard, Genoa could stand out as a valuable model for cities situated in hilly landscapes. Future studies should also play a crucial role in shaping urban forestry policies, steering them towards context-specific interventions that consider local soil properties, vegetation dynamics, and climatic conditions.