Can Pocket Parks Bridge Green Space Inequalities in High-Density Cities? A System-Level and Gradient-Based Approach

Cities worldwide face persistent inequalities in access to urban green spaces, a condition associated with reduced physical activity and poorer mental wellbeing. In high-density metropolises, land scarcity further intensifies these disparities. Although recent studies have highlighted the potential of small-scale green spaces, limited attention has been paid to their system-level and spatially differentiated roles within urban green infrastructure. Consequently, the equality implications of micro-scale interventions such as pocket parks across urban–rural gradients remain insufficiently understood. This study addresses this gap by examining the accessibility impacts of 475 pocket parks in conjunction with 433 large parks in Shanghai, using a multidimensional, citywide analytical framework. The Gaussian two-step floating catchment area (G2SFCA) method was applied within the 15-min community life circle framework to assess service coverage, population served, and per capita accessible green space, as well as their urban–rural differentiation patterns. Results indicate that the inclusion of pocket parks modestly increases overall service coverage (+3.41%) but substantially improves population access (+7.83%), converting 143.79 km 2 of previously unserved areas into areas with basic green space provision. Spatial effects vary along the urban–rural gradient: pocket parks generate high marginal population-service benefits and improve spatial equality in urban cores, strengthen green space service networks in peri-urban areas, and produce incremental accessibility gains in outer suburbs. Taken together, these findings provide a novel system-level understanding of how pocket parks function within urban green infrastructure networks, offering policy-relevant evidence to guide equality-oriented planning in high-density cities.