Urban greenery as a link

Urban greenery as a link between cities, rural communities, the countryside, and public health in agroecological biodistricts

In large urban centers and small municipalities in Mediterranean biodistricts, public greenery is often considered a mere decorative feature: something that beautifies, provides shade, and enhances the image of the place. In most cases, it is not considered a strategic tool for regional development. Furthermore, even to experts, urban greenery and the biodiversity of biodistricts often appear as separate worlds: urban greenery on one side, and that of small towns or agricultural areas on the other.

And this is precisely where the error of perspective arises. Public greenery certainly fulfills an aesthetic function, but it represents and accomplishes much more.
It can become a territorial infrastructure capable of connecting the environment of large cities with urban communities, the countryside, and public health. In a Mediterranean context like the current one, with frequent heat waves, thinking of parks, tree-lined avenues, neighborhood gardens, and green spaces in small towns as purely ornamental spaces is extremely reductive. If properly designed, these spaces can perform ecological, climate regulation, social gathering, therapeutic, and economic functions.

Therefore, it is entirely legitimate to state that urban greenery, in the broadest sense of the term, within an agroecological biodistrict, is capable of fulfilling multiple functions.
Among the main functions are:
• Reduction of urban temperature (urban cooling): shading and plant evapotranspiration contribute to lowering the temperature of the air and, above all, of urban surfaces (asphalt, concrete), mitigating the urban heat island effect.
• Maintenance of biodiversity and ecological corridors: habitat for pollinators and beneficial fauna; connection between urban green areas, peri-urban areas, and the countryside.
• Microbiota and health: increased opportunities for exposure to environmental microbial biodiversity, with potential benefits for the human microbiota, immunity, and inflammation.
• Air quality and urban comfort: improved thermo-hygrometric comfort and reduction of micro-environmental stress.
• Promotion of movement and prevention: spaces for walking and light activities with positive effects on cardiometabolic risk and mental well-being.
• Social function: community cohesion, reduction of isolation, and inclusion.
• Therapeutic function: therapeutic gardens and sensory pathways for gentle rehabilitation, neurodiversity, and stress management.
• Agroecological education: soil workshops, seminars on Mediterranean biodiversity, material cycles, and composting.
• Reduction of public costs (including healthcare): prevention and climate adaptation as tools to ease the pressure on services in the medium term.
• Public function: farmers’ markets, fairs, and local initiatives as a concrete expression of the principles of the biodistrict within residential areas.

This is where greenery stops being “decoration” and truly becomes a bridge: between city and countryside, between community and public health, between biodistrict and the future.
Therefore, green spaces, if properly managed and enhanced, become infrastructures capable of impacting environmental, social, cultural, and health determinants.

Urban greenery can rightfully represent a bridge between agroecosystems and citizens, and therefore between urban, rural, and countryside environments.
In other words, it can increase opportunities for contact with microbial and environmental biodiversity through soil, plants, and bioaerosols. This can contribute to positive effects on the human microbiota, including the gut microbiota, and therefore on immunity, low-grade inflammation, and the risk of chronic conditions.

This is not green rhetoric.
It is a realistic hypothesis, supported by growing scientific research, which is very solidly summarized in the review published in Environment International: “Greenspace and human microbiota: A systematic review” (Zhang et al., 2024).
In practice, greater exposure to green spaces, measured with objective indicators such as satellite data and land use, is often associated with greater microbial diversity and changes in the composition of the gut and skin microbiota (Zhang et al., 2024). The message is promising, but the evidence is still inconsistent, and the causality and duration of the effects remain aspects that need further clarification. Put more simply, we are beyond the sensational slogan but already within the functional complexity of the biodistrict system (Zhang et al., 2024).

Indeed, in a complex vision, a city park is not just a collection of plants and soil: it is also a system of biological dust, microbial and zoological communities associated with greenery, and, above all, the social community that experiences it.
Furthermore, the use of greenery tends to increase physical activity and reduce stress in all age groups and across all districts. These factors interact with the microbiota through neuroendocrine and immune pathways, influencing intestinal permeability and inflammation (Hartig et al., 2014; Twohig-Bennett & Jones, 2018).

It is within this framework that the “biodiversity hypothesis”/”old friends” fits: reduced contact with environmental biodiversity in hyper-urbanized and hyper-sterilized contexts can contribute to immune dysregulation and less resilient microbial profiles (Hanski et al., 2012; Haahtela, 2019). This does not mean that “more microbes” automatically equates to “better health”; this parameter acquires value based on the clinical condition of those who use green spaces.
This implies that, at the urban, rural, and agricultural population levels, the loss of exposure to biodiversity is a serious and biologically relevant problem that cannot be ignored.

Urban parks are typically evaluated based on their size and in relation to the size of the city in which they are located.
We believe that the evaluation of public green spaces (even in small areas) should take into account not only the quantity (square meters) but also the quality of the green space.
The difference between these two parameters is an ecologically “alive” green space that is truly experienced by the community. Indeed, studies on the microbiota warn against this. What matters is the quality, biodiversity, accessibility, and type of interaction with the designated green space (Zhang et al., 2024). In practical terms, a functioning park that truly acts as a bridge cannot be a weeded meadow maintained with synthetic chemicals; it must be a system managed with agroecological practices.

An agroecological biodistrict established within Mediterranean areas is often characterized by a microclimatic context of islands and intense, frequent heat waves, which impact cardiovascular and respiratory health, especially among the most vulnerable. For this reason, increasing and reshaping urban greenery should not be an aesthetic choice but an ecological measure of climate adaptation and prevention, useful in urban, rural, and agricultural settings.

A recent Italian study published in Nature Communications estimates that an increase in “residential greenness” may be associated with a significant proportion of avoidable mortality, with substantial differences between types of municipalities and levels of urbanization (Giannico et al., 2024). Other studies indicate that urban tree cover in Europe can produce potential health benefits related to mortality/morbidity attributable to exposure to pollutants, in specific settings and microenvironments (Sicard et al., 2025).

In the Mediterranean, where diet represents a cultural advantage (Mediterranean pattern), the key is to prevent the urban lifestyle from rendering it ineffective. Sedentary lifestyle, traffic stress, residential isolation, and limited exposure to nature “extinguish” part of the protective potential generated by parks. Urban greenery thus becomes a systemic ally, involving health, movement, relationships, and exposure to the environment.

When referring to the therapeutic function of greenery, however, it is important to clarify that a garden cannot replace therapy, but can support treatment, rehabilitation, and psychophysiological well-being. For decades, literature has shown that views of natural elements can be associated with better post-operative recovery than views of non-natural environments (Ulrich, 1984). Today, this translates into the design of therapeutic gardens for the elderly, for people with neurodiversity, for mental health management, gentle rehabilitation, and sensory pathways for the disabled. From a Mediterranean ecological perspective, this also means creating microclimates: shade, ventilation, and thermal safety.

Furthermore, urban and rural greenery, as well as cultivated and spontaneous biodiversity, can positively impact the National Health System. Savings are plausible and estimable, but we still need models built on local data.
That said, the general direction is clear: the more accessible and well-managed greenery there is in a Biodistrict, the greater and better the health outcomes (physical activity, mental well-being, cardiometabolic risk) and the fewer harmful environmental factors such as heat and pollutants (Twohig-Bennett & Jones, 2018; Giannico et al., 2024; Sicard et al., 2025).

However, the economic literature is increasingly translating these effects into value. Reviews highlight relationships between greenery, prescriptions, and medical spending (Patwary et al., 2024; Tate et al., 2024), and studies propose cost-effectiveness approaches to compare the use of NBS in urban settings for public decision-making (Panduro et al., 2024). For Italy, the work of Giannico and colleagues offers a concrete approach, providing an estimate of the potential health impact of residential greening on a national scale (Giannico et al., 2024), a good starting point for building specific economic models for the National Health Service (NHS).

The key, therefore, is governance: if we consider green parks as preventive healthcare infrastructure, not disconnected from the countryside, it makes sense to measure their performance and economic returns. In a country that spends heavily on chronic conditions, environmental prevention is not an extravagance: it is a strategy.

Furthermore, a well-designed public garden is also a social device: it fosters proximity, spontaneous interactions, and neighborhood networks throughout the area encompassed by a Biodistrict. Social cohesion is a determinant of health and, in vulnerable neighborhoods, can impact mental well-being, perceived safety, and physical activity.
In other words: green spaces must be part of equity policies.
If access is unequal, health becomes unequal.

This social function is particularly consistent with the Biodistrict concept: communities are not a public to be “served,” but rather local stakeholders. A park capable of offering green paths, social gardening, environmental education, and local events becomes a multiplier of relationships and healthy habits.
If we think in terms of a Biodistrict, urban green spaces become a hub of the territorial network. A Biodistrict connects organic agricultural production, landscape, community, and health. Bringing this approach to urban centers means bridging the gap between the countryside and the city and building an agroecological continuum.

In practice, parks should be treated as miniature agroecological systems: reconstructed soils nourished with high-quality organic matter, non-chemical management of wild flora, true plant diversity (not ornamental monocultures), stratification, resilient Mediterranean species, and scalar flowering. It makes no sense to declare a biodiversity objective (including microbial biodiversity) and then cyclically pollute urban habitats with herbicides and pesticides. This approach is perfectly aligned with the agroecological practices that govern biodistricts: fewer external inputs, more ecological processes, and sustainable practices.

Furthermore, an adequately sized urban park can also close ecological cycles; valorizing pruning residues, producing compost produced in controlled supply chains, managing organic matter as the “biological wealth” of urban soil, etc.
It is a concrete transfer of the circular economy to the urban environment.
And if we add urban and community gardens to greenery, we introduce a crucial component: social, nutritional, and tactile relationships—that is, real, daily “contact” with a living agroecosystem.

From this perspective, expanding and adequately managing public green spaces in cities is not an expense for purely ornamental purposes.
It is an investment in prevention, equity, and resilience, with realistic impacts on health (including microbiologically), social cohesion, and the economic burden on the National Health System. In a warming, aging, and increasingly urbanized Mediterranean, urban and rural green spaces, as well as biodiversity in local districts, are a public health choice.
And, frankly, it is one of the most concrete we have.

Francesco Di Lorenzo
Agronomist

Essential Bibliography
Bratman, G. N., Hamilton, J. P., Hahn, K. S., Daily, G. C., & Gross, J. J. (2015).
Nature experience reduces rumination and subgenual prefrontal cortex activation. Proceedings of the National Academy of Sciences, 112(28), 8567–8572.
https://doi.org/10.1073/pnas.1510459112

Giannico, O. V., Sardone, R., Bisceglia, L., Addabbo, F., Pirotti, F., Minerba, S., & Mincuzzi, A. (2024).
The mortality impacts of greening Italy. Nature Communications, 15, 10452.
https://doi.org/10.1038/s41467-024-54388-7

Haahtela, T. (2019).
A biodiversity hypothesis. Allergy, 74(8), 1445–1456.
https://doi.org/10.1111/all.13763

Hanski, I., von Hertzen, L., Fyhrquist, N., Koskinen, K., Torppa, K., Laatikainen, T., … Haahtela, T. (2012).
Environmental biodiversity, human microbiota, and allergy are interrelated.
Proceedings of the National Academy of Sciences, 109(21), 8334–8339.
https://doi.org/10.1073/pnas.1205624109

Hartig, T., Mitchell, R., de Vries, S., & Frumkin, H. (2014).
Nature and health. Annual Review of Public Health, 35, 207–228.
https://doi.org/10.1146/annurev-publhealth-032013-182443

Panduro, T. E., Nainggolan, D., & Zandersen, M. (2024).
Cost-effectiveness analysis of urban nature-based solutions: A stepwise ranking approach. Nature-Based Solutions, 6, 100186.
https://doi.org/10.1016/j.nbsj.2024.100186

Patwary, M. M., O’Brien, B. A., Preen, D. B., Bulsara, M., & Mohamed, M. A. (2024).
A systematic review and conceptual framework of green space exposure associated with healthcare expenditures and medical prescriptions.
Science of the Total Environment, 899, 169635.
https://doi.org/10.1016/j.scitotenv.2023.169635

Roslund, M. I., Puhakka, R., Grönroos, M., Nurminen, N., Oikarinen, S., Gazali, A. M., … Sinkkonen, A. (2020).
Biodiversity intervention enhances immune regulation and health-associated commensal microbiota among daycare children.
Science Advances, 6(42), eaba2578. https://doi.org/10.1126/sciadv.aba2578

Sicard, P., Agathokleous, E., Araminienė, V., Carrari, E., De Marco, A., Paoletti, E., & Calatayud, V. (2025).
Effect of tree canopy cover on air pollution-related mortality and morbidity in Europe: A modelling study.
The Lancet Planetary Health. https://doi.org/10.1016/S2542-5196(25)00112-3

Tate, K. A., Brown, C., & Stafford, M. (2024). A scoping review of economic evaluation methods and outcomes of urban green and blue space interventions for public health: Challenges and ways forward.
Ecological Economics, 223, 108266.
https://doi.org/10.1016/j.ecolecon.2024.108266

Twohig-Bennett, C., & Jones, A. (2018).
The health benefits of the great outdoors: A systematic review and meta-analysis of greenspace exposure and health outcomes. Environmental Research, 166, 628–637. https://doi.org/10.1016/j.envres.2018.06.030

Ulrich, R. S. (1984).
View through a window may influence recovery from surgery.
Science, 224(4647), 420–421. https://doi.org/10.1126/science.6143402

Zhang, Y.-D., Zhou, G.-L., Wang, L., Browning, M. H. E. M., Markevych, I., Heinrich, J., Yang, B.-Y. (2024). Greenspace and human microbiota: A systematic review. Environment International, 187, 108662.
https://doi.org/10.1016/j.envint.2024.108662

Zhang, Y. D., Fan, S. J., Zhang, Z., Li, J. X., Liu, X. X., Hu, L. X., Yang, B. Y. (2023). Association between residential greenness and human microbiota: Evidence from multiple countries.
Environmental Health Perspectives, 131(8), 087010.
https://doi.org/10.1289/EHP12186