Testing a rapid assessment approach for estimating ecosystem service capacity in urban green alleys

Urban green infrastructure – the network of greenspaces across cities – provides ecosystem services that are important for urban sustainability. Because of this, cities are increasingly redeveloping underused alleys into green infrastructure to improve ecosystem service capacity. But it remains unclear if these green alleys are delivering on the promise of supplying particular ecosystem services. The indicators usually used within green infrastructure to measure ecosystem services may not be suitable for green alleys because of the unique structure, vegetative features and level of community engagement of these alleys. Here we developed and tested a rapid assessment approach to evaluate ecosystem service capacity appropriate for use by community members and practitioners, using a green alley network in Montréal (Canada) as a case study. We collected data on green alley vegetation, structural form and indicators of four ecosystem services (food provision, habitat for pollinators, anthropogenic noise regulation and air temperature regulation). We modelled the relationships between vegetation, structural form, and ecosystem services, to determine if these rapidly assessed features of green alleys are appropriate indicators to evaluate ecosystem service capacity. Our results show that a rapidly assessed measure of vegetative ground cover is strongly associated with habitat for pollinators, highlighting potential for vegetative ground cover as an indicator for this service. Rapid assessments of alley vegetation were not associated with air temperature or anthropogenic noise, contrasting the findings of previous studies. Lack of relationships between the explanatory variables and the four ecosystem services suggests that further research is required to untangle these complex relationships. Our research provides a starting point for developing indicators of ecosystem service capacity that are tailored specifically to the unique structure and features of green alleys, a crucial step in testing the efficacy of this increasingly popular sustainable development strategy.