Revealing Perception–Habitat Mismatches in Urban Grey Infrastructure from a Multispecies Justice Perspective

Urban grey infrastructure, including transport corridors, flood-control systems, drainage facilities, railway margins, and industrial brownfields, is often treated in conventional planning as functionally vacant or ecologically marginal space. In this study, grey infrastructure is defined as engineered or infrastructure-dominated urban spaces and their residual or edge landscapes, rather than as green infrastructure. Yet such spaces may still contain spontaneous vegetation, water edges, soil patches, and sheltered microhabitats that can support birds, insects, small mammals, and other urban species in highly urbanized environments. From a multispecies justice perspective, this study examines spatial mismatches between PPGIS-derived public recognition and habitat quality modeled using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model in urban grey infrastructure. Using Zhanggong District, Ganzhou, China, as a case study, we developed an integrated framework that combines public participation geographic information systems (PPGIS), grid-based public recognition mapping, and the InVEST Habitat Quality model. Based on 260 valid questionnaires, participants identified locations associated with aesthetic preference and perceived habitat potential. These mapped perception points were converted into a grid-based public recognition indicator and compared with modeled habitat quality. The results indicate a marked perception-habitat mismatch. High public recognition was frequently associated with visually ordered, accessible, and highly managed urban spaces, whereas high modeled habitat quality was more strongly related to vegetated, riverine, peripheral, and semi-natural spaces. The spatial classification shows that aesthetic mismatch areas, where public recognition was high but modeled habitat quality was low, covered 43.20 km2, accounting for 7.16% of the study area, whereas hidden ecological value areas, where modeled habitat quality was high but public recognition was low, covered 118.21 km2, accounting for 19.59%. This study provides a replicable framework for identifying perception–habitat mismatches and supports more ecologically informed and inclusive strategies for regenerating urban grey infrastructure. More specifically, the study extends an established perception-ecology debate to grey infrastructure and residual urban spaces and demonstrates how PPGIS-derived public recognition and InVEST-modeled habitat quality can be compared within the same grid framework to locate spatially explicit alignment and mismatch.