The Green Roof Microbiome: Improving Plant Survival for Ecosystem Service Delivery

Abstract

Plants are key contributors to ecosystem services delivered by green roofs in cities including stormwater capture, temperature regulation, and wildlife habitat. As a result, current research has primarily focused on their growth in relationship to extensive green roof (e.g., substrates <15 cm depth) ecosystem services. Green roofs are exposed to a variety of harsh abiotic factors such as intense solar radiation, wind, and isolation from ground-level habitats, making survival exceedingly difficult. Plants in natural habitats benefit from a variety of interactions with fungi and bacteria. These plant-microbial interactions improve mechanisms of survival and productivity; however, many green roof substrates are sterilized prior to installation and lack microbial communities with unstudied consequences for green roof plant health and subsequent survival and performance. In this paper, we present six hypotheses on the positive role of microbes in green roof applications. In natural and experimental systems, microbial interactions have been linked to plant (1) drought tolerance, (2) pathogen protection, (3) nutrient availability, (4) salt tolerance, (5) phytohormone production, and (6) substrate stabilization, all of which are desirable properties of green roof ecosystems. As few studies exist that directly examine these relationships on green roofs, we explore the existing ecological literature on these topics to unravel the mechanisms that could support more complex green roof ecosystem and lead to new insight into the design, performance, and broader applications in green infrastructure.

Rekindling old friendships in new landscapes: The environment–microbiome–health axis in the realms of landscape research

“…This will require a comprehensive understanding of the various physical, spatial and biological factors that affect the composition, function and transmission of environmental microbiota in urban landscapes, and of the social factors that influence interactions (Figure 2). Fulthorpe, MacIvor, Jia, and Yasui (2018) discuss the importance of green roofs as an ecosystem service provider, and the importance of plant–microbe interactions, presenting a list of hypotheses for the positive role of environmental microbiota. These include drought tolerance, pathogen protection and phytohormone production.…”

The contribution of constructed green infrastructure to urban biodiversity: A synthesis and meta‐analysis

“…Studies and monitoring programs that assess the effects of GI on biodiversity should recorded these variables to provide information that can lead to better construction or management practices. There is an opportunity for researchers to expand their surveys to consider more diverse taxa (Fulthorpe et al, ). Estimates of plant community composition, both planted and spontaneous, could be particularly informative for characterizing GI habitat, and allow for future improvements to design and maintenance.…”

“…Studies and monitoring programs that assess the effects of GI on biodiversity should recorded these variables to provide information that can lead to better construction or management practices. There is an opportunity for researchers to expand their surveys to consider more diverse taxa (Fulthorpe et al, 2018).…”

“…However, there is relatively less quantitative evidence for the contribution of GI to biodiversity conservation (Williams, Lundholm, & Scott MacIvor, ). GI in cities can provide habitat for species in many ways including providing a substrate for plants and fungi (Fulthorpe, MacIvor, Jia, & Yasui, ; Thuring & Dunnett, ), providing water resources for aquatic animals (Lewis et al, ), acting as a refuge from reduced pesticide application (Lepczyk et al, ) and providing food resources, such as flowers for pollinators (MacIvor, Ruttan, & Salehi, ) or decomposing vegetation for detrivorous insects (Starry et al, ). Understanding the difference in habitat between GI and conventional infrastructure or natural counterparts is crucial for improving implementation.…”

“…b None of these comparisons were observed in the examined studies. & Yasui, 2018;Thuring & Dunnett, 2014), providing water resources for aquatic animals (Lewis et al, 2010), acting as a refuge from reduced pesticide application and providing food resources, such as flowers for pollinators (MacIvor, Ruttan, & Salehi, 2015) or decomposing vegetation for detrivorous insects (Starry et al, 2018). Understanding the difference in habitat between GI and conventional infrastructure or natural counterparts is crucial for improving implementation.…”