The future of urban agriculture and biodiversity-ecosystem services: Challenges and next steps

Urban landscapes are spatially constrained, and vegetative land uses that provide beneficial ecosystem services are difficult to maintain. Urban agricultural (UA) systems appear in many forms - from community farms and rooftop gardens to edible landscaping and urban orchards - and can be productive features of cities and provide important environmental services. As highly managed plant communities, UA can exhibit high levels of biodiversity, often exceeding that of other green space areas within the city. Additionally, it is likely that variation in vegetation cover, diversity, and structure influence not only the biodiversity in UA, but also the quantity and quality of ecosystem services supported by such systems. The biodiversity and ecosystem services (B&ES) of UA can have potentially large societal and environmental benefits for cities, such as enhanced food security, air quality, and water regulation. Yet few studies have synthesized knowledge regarding UA vegetation management impacts on the quantity, quality, and stability of B&ES provided. This article presents the first survey of the existing research on the characteristics of UA management and their potential to support ecosystem service delivery. Specifically, we examine: (1) biodiversity patterns in UA, (2) ecosystem services provided by UA, and (3) the challenges of promoting UA systems that support B&ES. Overall, our review reveals that varied vegetative structure, increased native plant diversity, and reduction of urban impervious surface are key features of UA systems that contribute significantly to urban biodiversity and provide important ecosystem services such as pollination, pest control, and climate resilience. We conclude with a discussion of critical gaps in current research and strategies to better understand and support UA and ecosystem services.