How and where sprawl and compact residential development are compared determines what’s better for biodiversity

Residential development profoundly changes biodiversity. A central issue in the management of these impacts is the role of urban form. We report the results of the first meta-analyses of the biodiversity value of compact versus dispersed residential developments. We identified six studies that compared biodiversity responses between existing developments and 14 studies that modeled the projected impacts of urban form. We show that the relative effects of compact versus dispersed developments are varied within and across studies, precluding any general statement about the benefits of one type of urban form over another. Variability in effect sizes resulted from the expected variability among biodiversity responses and the influence of spatial scale and local conditions, e.g., private and public landscape management practices. We suggest that future research on the effects of compact and dispersed developments on biodiversity should be designed with local planning and other conditions in mind and in collaboration with planning practitioners and local decision-makers and community members. Future research should also ideally thoroughly characterize the urban forms being compared in terms of their variation in landscape structure and socio-ecological context that is likely to impact biodiversity