Using past planning practice to inform biodiversity net gain in residential developments

Abstract Urban growth is a major driver of biodiversity loss, as natural habitats are destroyed or fragmented. To address this, nature‐positive initiatives aim to balance development with nature conservation. In the UK, Biodiversity Net Gain (BNG) was introduced through the 2021 Environment Act, requiring developers to deliver a minimum 10% biodiversity increase for new developments. Despite BNG's potential, doubts exist about local planning authorities' (LPAs) abilities to implement and enforce BNG effectively, due to resource limitations, inconsistent ecological expertise, and ineffective monitoring. This study examined 44 residential developments across two case studies where biodiversity measures were mandated through prior planning policy and assessed (i) how well ecological advice was integrated into planning decisions, and (ii) whether biodiversity measures were effectively implemented. The study revealed significant gaps between approved plans and actual implementation. The ecological advice transposed into planning decisions and approved documentation was biased towards European protected species (EPS) or more charismatic fauna. Additionally, many developments failed to properly implement biodiversity measures, with frequent deviations from approved plans for artificial and semi‐natural habitats. Solution . Improved awareness and knowledge of biodiversity, increased LPA resources, better communication between planners, ecologists and developers, stronger enforcement and improved monitoring are essential for BNG's success. Without these actions, BNG may fail to leave the natural environment in a measurably better state.