In recent decades, the concept of “forest” has expanded to include urban and peri-urban areas, where urban forests encompass trees located in parks, gardens, streets, and abandoned areas (Sanesi et al. 2010). Contemporary cities face critical challenges such as urbanization, climate change, pollution, and the decline of human well-being (Francini et al. 2022), to which urban greenery can respond by providing ecosystem services such as temperature mitigation, CO₂ sequestration, water regulation, noise reduction, biodiversity enhancement, and health benefits (Bottalico et al. 2017; Cox et al. 2017). A report by the International Resource Panel, established by the UN under the UN Environment Programme (UNEP), predicts that by 2050 as many as 2.5 billion people will move to cities, with an increase in consumption of natural resources of up to 125%. Although they account for only a few percent of the total area of the world, they are the cause of more than 70% of greenhouse gas emissions, more than 60% of energy consumption and the local rise in temperatures due to the heat island effect. The most evident problems in the urban environment can be identified in the emission of greenhouse gases, the management and disposal of large amounts of waste, high consumption of potable water and energy, traffic, and finally land consumption (Anguelovski et al. 2018).

The National Recovery and Resilience Plan (NRRP) investment for the protection and enhancement of urban and peri-urban green areas represents a unique project in Europe, focused not on traditional urban greenery but on afforestation, with the aim of strengthening biodiversity, improving quality of life, and counteracting phenomena such as air pollution and climate change. The interventions involve Italy’s 14 metropolitan cities and their 1,268 municipalities, covering an area equivalent to 15.47% of the national territory. By 2026, at least 4.5 million trees and shrubs are expected to be planted over approximately 4,500 hectares, of which 3.5 million will be in designated final areas. In this framework, the initiative promotes the use of native forest species in urban reforestation projects, both to gradually replace non-native, often invasive species introduced in the past for aesthetic reasons (Blasi et al. 2022), and because native species are better adapted to local conditions and capable of ensuring the availability of genotypes suitable for coping with future climatic challenges (Pardi et al. 2023).

Many cities worldwide have developed innovative projects: Paris (France) with the reforestation of the Champs-Élysées, Barcelona (Spain) with a strategic urban greening plan (Shafie 2015; Lindholm 2017), Melbourne (Australia) with a master plan aimed at reducing temperatures and promoting citizen engagement (Breen et al. 2020), and Medellín (Colombia) with its Green Corridors that combine reforestation and riverfront restoration. Across Europe, similar initiatives have also contributed to attracting tourism and improving quality of life.

The initiative, launched under the Urban and Peri-Urban Forestry Plan (Ministerial Decree MITE No. 493/2021), is based on the principle of “planting the right tree in the right place” following biogeographical and ecological criteria standardized at the national level. The diversity of species in urban contexts plays a fundamental role, as greater botanical heterogeneity enhances the resilience of urban ecosystems, increasing their ability to respond to environmental stressors, plant diseases, and climate change (Sarigu et al. 2025). Overall, the funded projects will enable the establishment of more than 4,700 hectares of new forests.

In this broader context, several regional studies have highlighted the floristic and dendrological richness of urban environments in southern Italy. Within this framework, Venturella et al. (2024) provides the first comprehensive census of ornamental species cultivated in public and private green areas of the Apulia region, offering a valuable reference for evaluating species selection in urban reforestation programs. Focusing on the Apulian territory as well, Pardi et al. (2025) document the presence of trees of remarkable historical and ecological significance in the Municipality of Bari, demonstrating how monumental specimens can represent both a cultural heritage and a key component of biodiversity within the urban landscape. Similarly, Di Gristina et al. (2025) emphasizes the importance of systematic inventories for understanding biogeographical patterns, the spread of exotic species, and their ecological implications in Mediterranean urban contexts.

Our survey focused on studying the diversity of forest vegetation in urban areas in Apulia. To this end, we conducted a census and analysis of urban reforestation projects planned and implemented in the six provinces of the Apulia region (Bari, Barletta-Andria-Trani, Brindisi, Foggia, Lecce, Taranto), with particular attention to spatial distribution and the composition of tree and shrub species. Among these urban reforestation projects, the reforestation project carried out in the city of Bari, particularly in the Poggiofranco – Municipio II district, is of particular interest, carried out in collaboration with the Di.S.S.P.A. of the University of Bari Aldo Moro, the municipal administration of Bari, the Campanale forest nursery (Cassano delle Murge, Bari), and the Alberitalia Foundation (Santa Sofia, Forlì-Cesena).

Initially, a comprehensive bibliographic and documentary review was conducted to identify and analyze all urban forestry projects promoted or implemented across the Apulia region. The main urban and environmental planning instruments were consulted, alongside official documents produced by local and regional authorities. Particular attention was given to projects funded within public environmental redevelopment programs, as well as to regional and national calls specifically addressing urban forestry, and initiatives implemented by municipal administrations or public–private partnerships. In parallel, technical reports, project plans, online documentation, and relevant gray literature were analyzed to reconstruct the most comprehensive overview possible of urban forestry activities in the region.

Subsequently, a census of the plant species used in the different interventions was conducted to verify and integrate the information obtained from the documentary research. This activity was carried out between August and September 2025, including direct field observations of the reforestation interventions. All recorded species are listed in Table 2, with nomenclature following Bartolucci et al. (2024) and Galasso et al. (2024). For each species, the botanical family, chorological type, biological form, and status (native or alien) in Italy are reported.

Finally, the collected data was mapped using QGIS software (QGIS Development Team 2023, https://qgis.org) to provide a comprehensive overview of urban forestry initiatives across the Apulia region.

Urban afforestation activities across the six provinces of the Apulia region involved a wide range of municipalities and urban and peri-urban areas (Fig. 1), with extensions ranging from a few hundred square meters to over 220 hectares. The interventions included the planting of tens of thousands of trees and shrubs, with the prevalence of native and Mediterranean species selected for their adaptability to the local pedoclimatic conditions.

In the province of Bari, the main projects, including “Terre dell’Alta Murgia,” “Dalla Murgia all’Adriatico,” Parco Rossani (Fig. 2), and Parco della Rinascita (Fig. 3), covered areas ranging from 0.03 to 220 ha, with plantings ranging from a few hundred to over 220,000 individuals (Table 1) (https://www.comune.bari.it/-/parco-della-rinascita-sull-area-ex-fibronit-approvato-il-progetto-esecutivo-dall-8-settembre-cantiere-a-pieno-regime-per-la-realizzazione-del-parco-ur; https://www.comune.bari.it/-/interventi-di-forestazione-e-greening-urbano-giunta-approva-i-progetti-esecutivi-di-5-interventi-per-un-totale-di-2-milioni-775-mila-euro). Trees species included Ceratonia siliqua L., Acer campestre L., Celtis australis L., Quercus ilex L., Fraxinus ornus L., and Pinus halepensis Mill., while shrubs included Myrtus communis L., Pistacia lentiscus L., Arbutus unedo L., and Rhamnus alaternus L.

The afforestation project carried out in the Poggiofranco district – Municipio II deserves mention. The project covered approximately 1.2 ha of calcareous soil and was implemented in February 2024 through collaboration between the University of Bari (Di.S.S.P.A.), the Bari municipal administration, Campanale forest nursery, and the Alberitalia Foundation. One- to two-year-old native tree and shrub species, grown from certified seeds collected in the forests of the Apulia Region, were planted in accordance with Legislative Decree no. 386/2003 (Candore and Girgenti 2019) to promote better establishment and adaptation. The planting scheme following an irregular curvilinear pattern (4 m between rows, 1.5 m within rows) at a density of 1,400 individuals (Fig. 4). Five tree species (C. australis, C. siliqua, F. ornus, Quercus suber L., Q. ilex) and four shrub species (A. unedo, M. communis, P. lentiscus, R. alaternus) were selected for drought tolerance and coherence with potential local vegetation. Q. ilex was the most planted species (400 individuals), followed by M. communis, A. unedo, P. lentiscus, and R. alaternus (180 each), while C. australis, C. siliqua, and Q. suber were least represented (60 each) (Tables 1, 2).

In addition, smaller-scale interventions were implemented in several other municipalities of the Province of Bari, including Ruvo di Puglia (https://www.comune.ruvodipuglia.ba.it/Amministrazione/Documenti-e-dati/PNRR-Piani-urbani-integrati-Verde-metropolitano-Green-Lane), Modugno (Fig. 5) (https://www.comune.bari.it/-/-mille-alberi-per-il-parco-urbano-asi-fastweb-per-il-futuro-di-bari-domani-l-avvio-del-progetto-di-forestazione-nell-ambito-della-campagna-nazionale-m), Molfetta (https://molfetta.news24.city/2024/02/19/al-via-opere-di-riforestazione-urbana-finanziati-per-500mila-euro/?amp=1), Triggiano (https://triggiano-api.municipiumapp.it/s3/7460/allegati/articolo-gazzetta-del-mezzogiorno-del-27-09-2022.pdf), Altamura (https://comune.altamura.ba.it/it/news/approvato-progetto-r-a-m-i-presso-parco-san-giuliano; https://www.altamuralife.it/notizie/messi-a-dimora-nuovi-alberi-in-via-manzoni-piazza-zanardelli-e-via-matera/), Gravina (https://www.gravinalife.it/notizie/programma-sperimentale-riforestazione-urbana/), Noci (https://www.noci24.it/politica/palazzo-di-citta/23685-ex-discarica-di-marrasca-completata-la-piantumazione-di-3-584-tra-alberi-e-arbusti) , and Putignano (https://gardendesignsrl.it/progetti/riqualificazione-urbana-del-quartiere-s-pietro-piturno-putignano-ba/), with areas ranging from 0.225 to 5 ha and planting densities of 214 to 11,000 individuals, using similar species (Tables 1, 2).

In the province of BAT (Barletta-Andria-Trani), the intervention in Barletta (https://www.barlettaviva.it/notizie/nasce-un-nuovo-parco-urbano-nella-zona-167/) involved the planting of 114 trees along urban streets, including A. campestre, C. australis, Ginkgo biloba L., Pinus pinea L., P. halepensis, and Quercus robur L. (Tables 1, 2).

In the province of Brindisi, two urban regeneration projects are underway, redeveloping the city of Brindisi entrance and creating a multifunctional park in the Perrino district (https://www.brundisium.net/index.php/brindisi-via-libera-dalla-regione-al-progetto-di-riqualificazione-urbana-previsti-interventi-su-porta-lecce-e-quartiere-perrino/). Planned plantings include P. lentiscus, Spartium junceum L., Viburnum tinus L., Cistus spp., Salvia rosmarinus Spenn., Thymbra capitata (L.) Cav., M. communis, C. siliqua, Tamarix arborea (Ehrenb.) Bunge, Quercus pubescens Willd., Q. ilex and Q. suber (Tables 1, 2).

In the province of Foggia, interventions included urban and industrial forests in Foggia (https://www.italpress.com/foggia-arbolia-e-leonardo-realizzano-bosco-urbano-con-1-600-piante/), Cerignola (https://ilmegafono.eu/2025/03/05/cerignola-in-verde-completata-la-piantumazione-di-160-alberi-prosegue-la-manutenzione-del-verde-pubblico/), and Torremaggiore (https://www.reteclima.it/sink/forestazione-urbana-alberi-a-torremaggiore/), with plantings of up to 1,650 individuals, including Q. ilex, Q. pubescens, F. ornus, Pinus halepensis, and various local shrub species (Tables 1, 2).

In the province of Lecce, peri-urban afforestation involved areas such as Borgo Pace (https://www.comune.lecce.it/news/dettaglio/2024/01/19/forestazione-urbana-via-ai-progetti-per-borgo-pace-orto--botanico-e-svincolo-tangenziale-est), Tangenziale Est, and the Salento Botanical Garden (https://www.provincia.le.it/lecce-presentazione-dellintervento-di-forestazione-sostenuto-da-edison-e-realizzato-in-collaborazione-con-la-provincia-di-lecce-e-la-citta-di-lecce/), with trees including Quercus coccifera L., Q. ilex, Q. suber, and P. halepensis, and shrubs including P. lentiscus, V. tinus, Cistus spp., and Erica arborea L. Additional significant interventions were carried out in Minervino (https://www.provincia.le.it/un-bosco-per-minervino-provincia-di-lecce-e-fondazione-sylva-per-un-salento-piu-verde/) and Nardò (https://fondazionesylva.com/nardo/), with a total of 11,000 planted individuals (Tables 1, 2).

Finally, in the province of Taranto, initiatives covered the Paolo VI district (https://www.arbolia.it/it/news-ed-eventi/arbolia-realizza-a-taranto-un-nuovo-bosco-urbano-da-oltre-4-500-.html), the Archaeological Park of the Magna-Greek Walls (https://www.panorama.it/attualita/taranto-bosco-urbano-wintre-arbolia), and the Tamburi district (https://www.comune.taranto.it/it/news/riqualificazione e rigenerazione del quartiere tamburi i lavori proseguono secondo il cronoprogramma), totaling approximately 5,500 individuals. Tree species included Quercus trojana Webb., Q. ilex, C. australis, P. pinea, and Platanus × hispanica Mill. ex Münchh., while shrubs included Phillyrea angustifolia L., P. lentiscus, R. alaternus, P. latifolia, Vitex agnus-castus L., and Rosa canina L. (Tables 1, 2).

The survey of urban afforestation projects, either completed or in progress across the six provinces of Apulia, reveals an evident predominance of the province of Bari, which accounts for 25 initiatives. Lecce follows with 6 projects, Foggia and Taranto with 3 each, Brindisi with 2, and finally BAT with only one project (Fig. 6).

Analysis of the selected species revealed a clear predominance of taxa belonging to the family Fagaceae (11 taxa), representing the most abundant group. The families Rosaceae (6 taxa), Lamiaceae, and Oleaceae (4 taxa each) followed in decreasing order of representation (Fig. 7).

Chorological analysis showed that most of the selected species are native taxa (44), indicating a preference for autochthonous flora to enhance urban resilience and ecological balance. Naturalized alien species accounted for 6 taxa, followed by casual aliens (3), and invasive and cryptogenic taxa (2) (Fig. 8).

The analysis of urban afforestation projects implemented across the six provinces of the Apulia Region highlights a growing awareness of the strategic role of urban green infrastructure in mitigating the negative impacts of urbanization and climate change. The concentration of interventions in the Metropolitan City of Bari suggests that metropolitan and densely populated areas are considered priorities for urban forestry investments. This pattern reflects not only the availability of financial resources, partly supported by NRRP, but also the increasing integration between urban planning, environmental sustainability, and climate adaptation policies (Konijnendijk et al. 2013; Kabisch et al. 2016).

The predominance of native taxa (44 out of 55 recorded species) clearly demonstrates a regional strategy aimed at strengthening the ecological resilience of urban and peri-urban ecosystems and conserving local biodiversity. The recurrent use of species belonging to the Fagaceae, Rosaceae, Oleaceae, and Lamiaceae reflects ecologically informed choices targeting taxa adapted to Mediterranean climatic conditions, characterized by high drought tolerance, resistance to elevated temperatures, and the ability to thrive on poor or calcareous soils typical of many urban areas in Apulia (Jim and Chen 2009; Gill et al. 2007). Within the Fagaceae, the genus Quercus emerges as the most represented, with eight taxa. Its predominance reflects not only its ecological versatility under different pedoclimatic conditions but also its strong cultural and landscape significance within the Apulian territory, where oaks represent a key identity element of the traditional forest landscape (Biondi et al. 2004).

The preference for native species entails multiple ecological and environmental advantages, as they generally require less maintenance and reduced irrigation inputs, while simultaneously supporting key ecosystem services, such as microclimate regulation, stormwater management, carbon sequestration, and mitigation of the urban heat island effect (Strohbach et al. 2012; Weber et al. 2014). Moreover, native species contribute to enhancing urban biodiversity by providing habitat and trophic resources for fauna and promoting ecological connectivity between urban and natural green areas (Niemelä 2014).

In this context, the pilot project implemented in Poggiofranco district site in Bari, the result of collaboration between the University of Bari Aldo Moro, the Municipal Administration of Bari, the Alberitalia Foundation, and the Campanale Forest Nursery, represents a significant case study. The establishment of a pilot green area with the planting of 1,400 tree and shrub individuals is consistent with the potential natural vegetation of the Cyclamino hederifolii–Quercetum ilicis association (Biondi et al. 2013). The use of xerotolerant taxa typical of the Mediterranean environment ensures the ecological compatibility and long-term resilience of the planted ecosystem within the dry Thermo-Mediterranean bioclimatic zone. Furthermore, interventions of this kind demonstrate the application of advanced design criteria based on irregular and curvilinear planting schemes, with spacing calibrated to promote establishment, growth, and adaptation to the urban microclimate.

A particularly relevant aspect of the analyzed projects is the rehabilitation of degraded or abandoned urban areas, including the former Fibronit industrial site in Bari, the former Marrasca landfill in Noci, and several peripheral or industrial zones. These interventions demonstrate how urban reforestation can serve as an effective tool for environmental and social regeneration, transforming neglected spaces into accessible and multifunctional public areas that enhance urban quality of life and foster social cohesion. The design of thematic parks, green memorials, and pedestrian pathways integrated within local urban planning represents an innovative approach in which ecological functions are combined with cultural and recreational values (Weber et al. 2014).

Despite the strong focus on native species, the occurrence of some naturalized or potentially invasive taxa, such as Broussonetia papyrifera and Platanus × hispanica, highlights the need for continuous monitoring and adaptive management to prevent undesirable impacts on urban biodiversity (Pyšek et al. 2020).

Overall, the results emphasize the importance of integrating ecological, phytopathological, and urban planning knowledge in the design and management of urban forests. Such integration is essential to maximize long-term ecological performance, enhance urban resilience to climate change, and strengthen the social and cultural dimensions of green infrastructure in Mediterranean cities.

Urban reforestation in Apulia represents an emblematic example of an integrated and sustainable approach, in which the selection of native species, the rehabilitation of degraded areas, and the careful planning of green spaces contribute to the creation of resilient urban environments. The Apulian experience provides a replicable model for other Mediterranean regions, demonstrating that well-designed urban forestry interventions can serve as effective tools for climate change mitigation, biodiversity conservation, and the enhancement of urban environmental quality.

In particular, the case study of Bari stands out as a significant example of how urban forestry can integrate scientific knowledge, local governance, and community participation to create multifunctional green spaces capable of providing both ecological and social benefits. The rehabilitation of degraded and abandoned areas through tree planting confirms the potential of reforestation as a means of environmental regeneration and social cohesion, capable of transforming the urban landscape toward greater sustainability and livability.

However, the occurrence of naturalized or potentially invasive species highlights the need for continuous monitoring and adaptive management to prevent undesirable ecological imbalances. Future planning should strengthen interdisciplinary collaboration among ecologists, urban planners, and policymakers to ensure that species selection, planting design, and management practices are consistent with local ecological conditions and long-term climate resilience goals.

In conclusion, this survey demonstrates that urban reforestation, when grounded in sound ecological principles and integrated within sustainable planning strategies, can serve as an effective and replicable model for Mediterranean cities facing the combined challenges of urban expansion and climate change.