Benefits of the ecosystem services provided by urban green infrastructures: Differences between perception and measurements

Urban green infrastructures (UGIs) are being increasingly recognized as key providers of ecosystem services (ES) in cities. However, many developing countries still lack the public awareness of the concepts of UGIs and their ES, including the benefit & monetary value of the UGIs' services, the willingness to pay (WTP) for the UGIs' services. The relationship between the benefits & monetary value of and the WTP for the services of UGIs has not been extensively investigated. These two aspects were respectively defined as ES supply and as ES demand in the current study, in which their relationship was scientifically described. Meanwhile, the influential factors of the deviation between ES supply and ES demand were explored. Adopting Guangzhou City (China) as a case, the main ES supply of UGIs in three public green spaces including air pollutant removal, daytime temperature reduction, rainwater runoff regulation, and noise abatement was first assessed with field measurements. Further, the main ES demand including people's preferences, satisfaction, and WTP for the UGIs' ES was analyzed with survey and statistical analysis. In total, 405 valid questionnaires were distributed to collect the data of ES demand and were analyzed by the nonparametric Kruskal-Wallis H test and a binary logistic regression model. The monetary valuation was used to unify the benefit valuation standards provided by different ESs, so as to more intuitively reflect the contribution of different ESs and compare these with ESs demand which uses WTP as one of the indicators. The results showed significant differences between ES supply and ES demand. The major evidence was that the regulation services could supply most of the ES benefits, while the cultural services were the most demanded by respondents. People had diverse sensitivity to the different types of ES provided by the UGIs. Cultural services were the most easily perceived by the respondents and considered as the top one, followed by regulation services. In addition, the outcome of the survey revealed different criteria regarding ES demand by people, and varying influencing factors for people's satisfaction and WTP. Benefits, such as education opportunities, entertainment, and health values provided by UGIs in cultural services were more favored by respondents. Last, the statistical analysis confirmed that sociodemographic factors significantly influence people's WTP. This study suggests that UGIs should be oriented towards multifunctional construction, thereby emphasizing the relationship and balance between ecological integrity and social perception.