Assistant Professor Biological Sciences, Ecology & Evolutionary Biology, University of Toronto
Background/Question/Methods
Increasing attention has been given to how urban ecosystems influence biodiversity and ecosystem services as more of the Earth’s surface becomes developed. The built environment is largely seen as detrimental to ecosystem functioning as the natural habitat is removed and replaced with impervious surface. However, cities are heterogeneous and complex environments that likely have differential impacts on the ecosystem services provided depending on the scale and particular service being examined. For example, the effects that urbanization has on biodiversity at the local level may be different than at the landscape level. Here we present a novel meta-analysis of peer-reviewed literature on multiple ecosystem services (biodiversity, ozone pollution, soil pollution, and temperature amelioration). We assess the magnitude that each of these services has in urban green spaces compared to non-urban systems. Additionally, we wanted to know how these services vary across different scales relevant to urban systems ranging from the plot to landscape level.
Results/Conclusions
Through a synthesis of the past ten years of urban ecosystem functioning literature, our meta-analysis found that both scale and ecosystem service type varied between urban and non-urban locations. Across studies, we found that urban green spaces had lower ecosystem services produced relative to non-urban counterparts (mean = -1.93, CI = (-3.36, -0.51), p = 0.008). However, these effects were not ubiquitous across services and scales. Separating the scale examined in each study showed that ecosystem services produced at the landscape level were lower in urban green spaces, whereas plot level services were relatively similar between urban and non-urban systems (mean = -3.46, CI = (-8.85, 1.94)). When separated to specific services, we found that biodiversity, ozone pollution, soil pollution, and temperature amelioration had varied responses to urban systems (mean = -2.86, CI = (-7.48, 1.76)) with services such as ozone pollution being negatively impacted and diversity staying relatively even between urban and non-urban systems. We conclude that ecosystem services are not only differentially affected by urbanization, but by the scales at which they are examined.
