Plants in the city: understanding recruitment dynamics in urban landscapes

In cities, naturally regenerating plant populations are critical in sustaining both ecological function and ecosystem services. However, scientists have a limited understanding of the urban ecosystem conditions and stressors that influence basic life-history processes and constraints for plant populations. Here, we synthesize current research on the recruitment dynamics of urban plants (processes associated with adding individuals to populations) and present a conceptual framework for urban recruitment limitation. From grasslands to forests, and from natural to constructed habitats, multiple urban drivers - including climate, land-cover change, pollution, and biotic invasions - affect plant recruitment. These drivers often interact, and their effects are frequently species-, habitat-, or region-specific. Furthering a "mechanistic" understanding (one that focuses on the underlying ecological mechanisms of observed phenomena) of how these drivers alter plant population dynamics will improve the conservation, management, and restoration of urban greenspaces.