People often think about cities as being separate from nature, but the reality is that cities are intimately connected to the natural systems that support life. There’s a concept called ‘ecological services’ that is worth understanding when we think about our cities. Basically, ecological services talk about the activities that naturally occur in nature – for example a wetland naturally cleans water; a tree naturally cleans the air – all for free. As more and more people move to cities, it is important to continually improve how we integrate our natural and urban systems. With all that in mind, we wanted to talk to someone who understands the relationship between natural systems and cities. Danah Duke is the executive director of the Miistakis Institute.