1. Protected areas (PAs) are a key intervention for conserving biodiversity and ecosystem services. A major challenge for PAs is the control of invasive non-native plants that spread into PAs from surrounding sources such as forestry plantations. The links between invasions and different source populations are poorly understood, making it difficult to apportion responsibilities for control costs. 2. We estimated the effect of plantations of invasive pines (Pinus species) on the spread of these trees...