Indicators of visual and ecological complexity of urban wetlands and lakes in Stockholm

• Visual and ecological complexity assessed via landscape and plant diversity data. • Edge contrast consistently predicted visual complexity across data sources. • Patch isolation effects differed between photo-based and orthophoto-based data sets. • Patch elongation is negatively associated with plant species diversity. • Findings suggest indicators of visual and ecological quality for urban planning. Recognising the aesthetic attributes of urban wetlands and lakes is crucial for guiding their sustainable management, as it fosters social motivation, which in turn contributes to the preservation of water ecosystems. Systematic assessments of landscape aesthetic quality based on visual indicators become essential for urban planning and design. This study focuses on the analysis of visual complexity as a key concept of the aesthetic quality of urban wetlands and lakes in the Stockholm area using indicators of visual quality. It also aims to enhance ecologically oriented landscape aesthetics by investigating how indicators of visual quality correlate with biodiversity parameters. The study employs landscape structure analysis combined with plant diversity analysis, applying a set of aerial photo-based and landscape photo-based indicators. The methodology used included GIS analysis of landscape photos and orthophotos, the identification of landscape metrics in FRAGSTATS, the selection of indices and visual indicators, plant species richness analysis, the evaluation of landscape structure using multivariate canonical analysis and assessment of the relationship between spatial landscape structure using mixed-effects modelling. The novelty of this study lies in introducing new indicators of visual complexity and in exploring the link between visual and ecological complexity in urban wetlands and lakes. The results showed: 1. that the analyzed canonical axes explained 17–50 % of the variation and were correlated with landscape metrics that serve as indicators of shape, aggregation, and edge contrast, suggesting that these metrics could be potential objective indicators of visual complexity; 2. that the effect of edge contrast was consistent but the effect of the index of patch isolation was different in different data sources; 3. and that patch elongation was negatively associated with Shannon diversity, suggesting that it is an integrative metric linking visual and ecological complexity. The results highlight the importance of integrating visual and ecological complexity indicators into monitoring programs and decision-making for managing urban green–blue infrastructure, promoting effective governance, preventing wetland degradation, and supporting participatory discussions for shared understanding.