An improved method for assessing mismatches between supply and demand in urban regulating ecosystem services: A case study in Tabriz, Iran

Abstract

Regulating ecosystem services provided by urban forests are of great importance for the quality of life among city dwellers. To reach a maximum contribution to well-being in cities, the urban regulating ecosystem services (URES) must match with the demands in terms of space and time. If we understand the matches or mismatches between the current urban dwellers' desired quality conditions (demand) and the supply of URES by urban forests (UF) in the cities, this will facilitate integrating the concepts of ecosystem services in urban planning and management, but such an assessment has suffered from major knowledge limitations. Since it is complex and problematic to identify the direct demands for URES and the spatiotemporal patterns therein, improving the demand indicators can help to determine the actual requirements. In this paper, a methodological approach based on indicators is presented and demonstrated for two important URES: air quality improvement and global climate change mitigation provided by urban trees and shrubs. Four air quality standards and greenhouse gas reduction targets were used and compared to supplies of the URES in Tabriz, Iran. Our results show that the mean contribution of the URES supply to air quality standards and greenhouse gas reduction targets is modest. Hence, in Tabriz, there is a strong mismatch between demand and supply. Mismatches at the city scale will have to be reduced by both a reduction in pollutant emissions and an increased provisioning of URES supply through urban greenery. The presented assessment approach and the results for Tabriz make it explicit how different the demands and supplies of the two studied URES are, and we expect similar mismatches in many other cities. Therefore, our approach, relatively simple but still realistic and easy-to-apply, can raise awareness about, and the utility of, the ecosystem services concepts for urban planning and policymaking.

Fig 1. Location of Tabriz municipality, land use classes, and sample points.

Fig 2. Historical trends in annual mean temperature and precipitation in Tabriz (1951–2017)—(Data source: [73]).

Fig 3. Dynamic trends in the annual mean concentration of air pollutants in Tabriz (2004–2104)—(Data source: [80]).

Fig 4. The methodological steps to quantify URES supply through i-Tree Eco model.

Fig 5. Flowchart for identifying and assessing matches and mismatches between the supply and demand of urban regulating ecosystem services (URES).

Fig 6. Average percentage of air quality improvement by urban trees and shrubs at the city scale.

Fig 7. Results for air purification supply and demand (the value of CO in supply diagram is based on thousands) indicators for the case study.