Vegetation diversity in structure, species or colour: Coupling effects of the different characteristics of urban green spaces on preference and perceived restoration

• Vegetation colour diversity impacts preference 2.55 times more than structural diversity and species richness. • Vegetation structure, species richness and colours significantly enhance public preferences and perceived restoration. • Urban green space features do not always improve preferences and restoration, showing both synergistic and erosive effects. • Medium complexity in vegetated landscapes is preferred and has greater restorative potential. • Public preferences and restoration should be understood from multi-dimensional perspectives, not a single element. The benefits of urban green spaces for human beings have become increasingly evident amid global urbanisation, which has exacerbated health issues. However, the effects of different characteristics of urban green spaces, such as vegetation structure, species and colour, on human health and well-being remain poorly understood. This study addressed this gap using a mixed design (between-subjects and within-subjects) and a 2 × 2 × 2 factorial design to combine structural diversity, species richness and colour diversity of vegetation. Participants experienced virtual scenes created on Mars to assess preference and perceived restoration. Through analysis of variance (ANOVA), beneficial features of urban green space and formulated equations using a linear regression model to explain the joint effects of these characteristics were identified. Results indicate that rich structure, species and colours of vegetation significantly enhance preferences and perceived restoration, with colour having the greatest impact ─ 2.55 times greater than structural diversity and species richness. However, the superposition of multiple features does not mean ‘the more the merrier’, as binary and ternary interactions can have synergistic and erosive roles. Therefore, medium complexity is most beneficial for improving health and well-being. Overall, urban green space construction should consider multiple dimensions for a harmonious relationship between humans and nature, promoting sustainable development.