Wildness and habitat quality drive spatial patterns of urban biodiversity

Urban green and blue spaces (UGBS) are key for biodiversity conservation. Many studies focus on UGBS benefits for well-being, but how UGBS ecological and quality influence urban biodiversity is still poorly understood. We analysed the predictive accuracy of urban wildness (UW) and habitat quality (HQ) spatial patterns to biodiversity in the city of Vitoria-Gasteiz, Basque Country. Using GIS techniques, we mapped relative UW as a landscape quality, considering remoteness, challenging terrain, and perceived naturalness. We further evaluated HQ using the InVEST habitat quality module, including data on habitat sensitivity to threats (e.g. population density, light and noise pollution, accessibility) and suitability for biodiversity support, based on a parametrization by expert consultation. We compared UW and HQ to observed species richness obtained from crowd-sourced databases as a biodiversity proxy. UW and HQ models predicted general biodiversity urban patterns, being particularly adequate in UGBS. Peripheral UGBS were associated with higher UW and HQ and positively correlated to biodiversity, as opposed to the smaller-sized centrally located UGBS, more exposed to threats. Both predictors significantly explained biodiversity, and HQ better accounted for threat susceptibility in UGBS. Our findings suggest that small-sized UGBS, such as parks and squares, fail to effectively support urban biodiversity, due to their high exposure and vulnerability to threats, particularly in centric areas. Emphasizing efforts in larger centric UGBS with rewilding strategies (e.g. lowering management frequency) and reducing exposure to threats is essential to increase the habitat quality of UGBS and thus support urban biodiversity.