Moth assemblages within urban domestic gardens respond positively to habitat complexity, but only at a scale that extends beyond the garden boundary

‘Wildlife-friendly’ gardening is a dominant theme in the media that readily engages public attention. However, there is little empirical evidence of the ecological benefits of increased habitat quality of individual domestic gardens. This study uses light-trapping to examine the response of moth assemblages to domestic gardens that are assessed in terms of their habitat complexity (simple and complex) both within the garden and extending out to a 30 m radius that includes surrounding habitats. The results clearly show that moth assemblages were influenced by complex habitats (particularly increasing levels of the variable shrubs and decreasing levels of artificial surfaces), but only at a scale that extended beyond the garden boundary to include the surrounding area. In other words, neither the complexity of the habitat within the garden or the size of the garden had any influence on the abundance or diversity of the moth assemblage. These results have implications for both garden management and landscape planning – if domestic gardens are to be a useful component of strategies to reduce biodiversity loss within the urban environment then they should provide good habitat quality and be managed as a network of interconnected patches rather than as individual units.