The importance of residential vegetation cover for urban birds – linking biodiversity thresholds to standards for human well-being

The increasing urbanization of landscapes raises the need to understand and optimize the role of urban green spaces in protecting both human well-being and biodiversity. However, green space requirements for supporting diverse faunal groups, such as birds, have not been linked to existing human-centric guidelines. While the evidence for the potential of residential areas in promoting avian diversity through local vegetation structures increases, the relative importance of these habitats compared to larger green spaces in the surroundings is unclear. We sampled 90 residential blocks within the city of Munich, Germany, in order to investigate the role of local vegetation cover and proximity to green spaces for avian diversity and abundance. The blocks were stratified along orthogonal gradients of vegetation cover and distance to green spaces, allowing for the assessment of the independent effects of these variables. Results of linear mixed effect models showed strong effects of total vegetation cover on both abundance and diversity of birds, while the distance to green spaces had no significant effects. Using Hill numbers as diversity measures revealed that the influence of large trees was strongest for rare species, but became insignificant when focusing on abundant species. Threshold values derived from conditional inference trees indicated significant increases in bird diversity when total vegetation cover exceeded 20–40% and lower vegetation exceeded 11%. Considering existing standards on green space accessibility for human health and climate regulation, we show that providing at least 10–20% vegetation cover within residential blocks can significantly benefit both biodiversity and human well-being. Our results advance fundamental understanding of how local vegetation structure shapes avian species diversity in urban landscapes, while also offering applied guidance for biodiversity-friendly planning. Together, they highlight the potential of urban planning to create multifunctional green areas that integrate ecological and societal needs.

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