Credit: Isabella Richmond Green alleys—residential laneways redesigned to enhance residents' quality of life, boost social cohesion and improve biodiversity—are gaining traction in cities across North America. But as the concept spreads, it remains loosely defined: what exactly counts as a green alley, and what benefits can it provide? According to a new Concordia-led study published in the journal Ecosystems and People , there is no single definition of a green alley, as these spaces can take many forms. While green alleys are generally linked to more biodiversity and stronger social cohesion, the study found they do not always achieve both at the same time; results depend on alley design and purpose. The study was led by Isabella Richmond, Ph.D. 25, and supervised by Carly Ziter, assistant professor of biology at Concordia. It was conducted in collaboration with Université de Montréal and Université de Montréal à Québec.…