Organized Oral Session
Lee Skabelund, Professional/Registered Landscape Architect
Associate Professor of Landscape Architecture
Kansas State University, Kansas, United States
Background: Green roof (GR) ecosystems (roofs with plants and soil-like substrate overlaying a waterproof membrane) have arisen as a prevalent nature-based solution in cities worldwide, installed for their ability to provide much-needed ecosystem services including reduction of stormwater runoff, localized cooling, carbon sequestration, aesthetic enhancement, and biodiversity support. In the dense urban core, green roofs provide one of the few viable options for urban greening. The assumption on installing a GR is that the functions supporting ecosystem services will continue to be provided at a high level in perpetuity. It is known however that terrestrial ecosystems are dynamic over time due to (sometimes) predictable changes in soil and vegetation properties.
GR research has blossomed in recent years accompanying the rapid increase in their installation. As spatially-constrained well-defined ecosystems replicated extensively within and among different regions, GR provide an excellent opportunity to study a wide range of ecological processes. However, the vast majority of research has taken place on newly constructed roofs or in small short-lived test plots. Very little is known about potential long-term changes. Given that the intended lifespan of GR is 50 years or more, there is an urgent need to understand how these ecosystems will function not just years, but decades into the future.
Goal: The goal of this session is to provide an overview and update on the state of knowledge regarding longer-term (5-10 years or more) development of green roof ecosystems, their biotic communities, their functional performance, and their ecosystem service provision.
Importance and Interest to ESA membership: Given that GR plant community and substrate characteristics change over time there are potentially significant implications for ecosystem service provision. In contrast to natural ecosystems, soil and plant communities in green roofs have not co-developed but were rather engineered/designed from the outset to perform specific functions. Rooftops are also high-stress ecosystems with exposure to wind, high temperatures, and frequent dry periods. GR may thus give rise to a development trajectory distinct from analogous natural terrestrial ecosystems, giving insight into both engineered and natural ecosystems.
GR research allows ecologists to study ecological processes in a defined spatial scale and can connect to urban LTER research. GRs can function as important stepping stones for pollinators, birds, and other wildlife. How well GRs support wildlife and provide other ecosystem functions will only be known if ecologists help designers, engineers, and facility managers understand their benefits and limitations.
Presenting Author: Christine Thuring – British Columbia Institute of Technology
Co-author: Nigel Dunnett – University of Sheffield
Presenting Author: Kelly Ksiazek-Mikenas – Elmhurst University
Presenting Author: Amy Heim – University of Montreal
Presenting Author: Lee R. Skabelund, Professional/Registered Landscape Architect – Kansas State University
Presenting Author: Dustin Partridge – New York City Audubon Society
Co-author: Kaitlyn Parkins – American Bird Conservancy
Presenting Author: Ishi Buffam – Swedish University of Agricultural Sciences