As urbanization increases globally and the natural environment becomes increasingly fragmented, the importance of urban green spaces for biodiversity conservation grows. Residential landscapes with private gardens are particularly crucial settings for biodiversity conservation, being a major land cover and places where people most regularly experience nature. Gardens and adjacent habitats form interconnected networks and a landscape ecology framework is necessary to understand the relationship between the spatial configuration of garden patches and their constituent biodiversity. Garden management is also influenced by an array of socio-demographic and economic factors that operate across scales, and understanding the social drivers behind gardening attitudes and behavior is paramount to harnessing gardens for conservation. Using a novel, nested sampling design based on gradients in landscape structure and socio-economic status across the UK city of Leeds, this interdisciplinary study develops and applies a mixed method approach, including householder questionnaires, interviews and ecological surveys, to determine the predictors of bird and bee richness and abundance in private gardens and neighborhoods.
Generalised linear models (GLMs) revealed that both birds and bees responded to ecological and social drivers operating at multiple scales. Bird species richness and abundance within gardens was best predicted by a combination of householder social status, supplementary feeding, garden vegetation and the configuration of habitat in the surrounding landscape. At the neighborhood scale, vegetation complexity had the most consistent influence on bird metrics, although landscape connectivity was the best predictor of bird abundance. Bee species richness and abundance within gardens was strongly associated with the availability of local floral resources, with marginal support for the effects of surrounding landscape configuration, garden management intensity and garden vegetation. Surprisingly, we found that neighborhood income level was a strong negative predictor of the richness and abundance of bees within gardens. Householder interviews revealed that social pressures to maintain neighborhood standards through gardening practices were particularly prevalent in wealthy neighborhoods. We suggest that the negative relationship between socio-economic status and bee richness and abundance can be explained by the greater tolerance of weedy plant species and unkempt brownfield sites in less affluent neighborhoods that provide greater floral resources and nesting opportunities for bees. The results show that planners and policymakers seeking to maximise the conservation value of urban ecosystems would benefit from considering the spatial configuration of interconnected garden patches and from better understanding of the social processes that underlie householder decision-making.