Evaluating the Ecological Functions of Vegetation Cover in Enhancing Citizens’ Health and Quality of Life in the Masoudieh and Nezamieh Gardens, with an Emphasis on the Baharestan District of Tehran

Abstract

Rapid and unsustainable urbanization in Tehran, particularly within dense and historic districts like District 12, has led to a reduction in vegetation cover, an increase in impervious surfaces, and exacerbated air pollution. These conditions have resulted in consequences such as the formation of urban heat islands, increased concentrations of particulate matter, and threats to public health, especially in the southern and western parts of Tehran. Vegetation plays a key role in improving air quality and citizen health through its ability to absorb carbon dioxide, produce oxygen, and reduce pollutant concentrations. However, the decline of green spaces in historic gardens like Negarestan, Masoudieh, and Nezamiyeh has weakened these ecological functions. This research analyzes the changes in vegetation cover in Masoudieh and Nezamiyeh gardens from 1887 to 2025 (1266 to 1404 in the Solar Hijri calendar) and examines its relationship with air quality and the health of local residents, using historical data, satellite imagery, software simulations (i-Tree Canopy), and field surveys. The results indicate a dramatic decrease in the green cover of Nezamiyeh Garden from 4 hectares in 1887 to 0.026 hectares in 2025, while Masoudieh Garden's cover has decreased from 0.9 to 0.74 hectares. This significant loss of vegetation has led to a severe decline in the capacity to filter pollutants, reduced carbon dioxide sequestration, and a diminished economic value of ecosystem services. Questionnaire findings also reveal that citizens perceive the reduction in green space and the rise in air pollution as direct causes of physical and mental health problems, emphasizing the need for formal institutional interventions to restore historic gardens and expand green areas. For future planning, two scenarios were modeled: increasing the green cover in the gardens to 35% and 70%. The minimum scenario (35%), which utilizes vacant spaces and roadsides, represents a realistic approach for gradual restoration. The maximum scenario (70%), involving the complete reconstruction of the gardens, offers the potential to restore historical ecosystem services. The modeling shows that increasing vegetation cover significantly reduces the concentration of particulate matter, enhances carbon dioxide absorption and the value of ecosystem services, and improves public health. This research underscores the importance of reconstructing and preserving historic gardens in dense urban fabrics and proposes practical solutions for developing historical green spaces to achieve environmental sustainability, ecological justice, and an enhanced quality of life for citizens.