THE CONTRIBUTION OF CONSTRUCTED GREEN INFRASTRUCTURE TO URBAN BIODIVERSITY: A SYNTHESISED ANALYSIS OF ECOLOGICAL AND SOCIOECONOMIC OUTCOMES

Abstract

This study examines how constructed green infrastructure green roofs, bioswales and rain gardens, pocket parks, and constructed wetlands contributes to urban biodiversity and neighborhood social outcomes, and integrates a narrative review of 50 peer-reviewed studies to ground the framework. The purpose is to quantify links between designed vegetated systems, site-level biodiversity, and perceptions of well-being, safety, satisfaction, place attachment, and usage. Design is quantitative, cross-sectional, and case-based. The sample comprises 180 CGI sites across diverse urban contexts with standardized pedestrian catchments, alongside 5,220 intercept-survey responses. Key variables include CGI extent, quality and maintenance, and connectivity; biodiversity indices (species richness, abundance, Shannon’s H′, Simpson’s 1–D); and social outcomes measured on 5-point Likert scales, with covariates for NDVI, density, land-use mix, transit access, street connectivity, and neighborhood deprivation. The analysis plan specifies descriptives, Pearson or Spearman correlations, and multivariable models: negative binomial for counts, OLS with HC3 errors for continuous outcomes, ordinal logit for usage, plus bootstrapped mediation and prespecified moderation by typology, maintenance, and SES. Headline findings show CGI quality is the strongest ecological predictor, connectivity adds smaller but consistent benefits, and extent is positive yet modest; biodiversity is positively associated with well-being and satisfaction and, to a lesser extent, safety and attachment. Mediation tests indicate 20 to 35 percent of the quality effect on well-being and satisfaction is transmitted through biodiversity. Returns are larger where maintenance is higher, somewhat smaller on access-limited roofs, and stronger for safety in lower-SES catchments. Implications include prioritizing native-rich, vertically structured plantings, funding visible maintenance as a performance multiplier, completing green networks, and adopting a lean site-level dashboard that jointly tracks biodiversity and social outcomes.