Soil Microbial Assemblages Are Linked to Plant Community Composition and Contribute to Ecosystem Services on Urban Green Roofs

Abstract

Green roofs are a way for cities to mitigate environmental stressors, such as heatwaves and droughts. However, these environmental stressors can adversely affect green roof vegetation, causing challenges for plant growth and survival and subsequently reducing the ability of green roof systems to deliver critical ecosystem services, such as heat mitigation and nutrient cycling. Plant-associated microbes may facilitate the resilience and tolerance of green roof vegetation to climate-associated stress. However, despite their crucial role in plant growth and survival in natural ecosystems, there has been little research on plant-associated microbes in green roof systems. Plant choice on green roofs may also determine which microbes established in green roof growing media, and particular plant-microbial combinations may be more resilient to environmental stress. This project sought to characterize soil microbial community composition on green roofs across New York City with different plant palettes and assess how different combinations of green roof plant species and root-associated microbial assemblages responded to isolated and simultaneous heat and drought treatments. We surveyed green roofs planted with either Sedum species or with a mixedvegetation palette (i.e., wildflowers, grasses, and succulents). We found that mixedvegetation and Sedum green roofs had distinct soil bacterial and fungal communities (p < 0.0001) with a higher relative abundance of mycorrhizal fungi on mixed-vegetation roofs, and higher pathogen loads on Sedum roofs. Concurrently, we conducted a greenhouse experiment in which plants were grown from seed with live inocula collected from the two different types of vegetation on the green roofs we surveyed. Hoch et al. Green Roof Soil Microbial Communities We observed that plant species, soil inoculum, and abiotic stress treatment was correlated with shifts in soil fungal communities. This study demonstrated that soil microbial assemblages on green roofs are linked to the roof vegetation, and that they may facilitate green roof plants' tolerance and resilience to environmental stressors.

A global metagenomic map of urban microbiomes and antimicrobial resistance

“…Urban travelers bring their commensal microorganisms with them as they travel and come into contact with organisms and mobile elements present in the environment. The study of the urban microbiome and the microbiome of the built environment spans several different projects and initiatives, including work focused on transit systems ( Afshinnekoo et al., 2015 ; Hsu et al., 2016 ; Kang et al., 2018 ; Leung et al., 2014 ; MetaSUB International Consortium et al., 2016 ), hospitals ( Brooks et al., 2017 ; Lax et al., 2017 ), soil ( Hoch et al., 2019 ; Joyner et al., 2019 ), and sewage ( Fresia et al., 2019 ; Maritz et al., 2019 ), among others. For the most part, these efforts have only studied a few select cities on a limited number of occasions.…”

Global Genetic Cartography of Urban Metagenomes and Anti-Microbial Resistance

“…The study of the urban microbiome and the microbiome of the built environment spans several different projects and initiatives including work focused on transit systems (Afshinnekoo et al, 2015;Hsu et al, 2016;Kang et al, 2018;Leung et al, 2014;MetaSUB International Consortium. Mason et al, 2016), hospitals (Brooks et al, 2017;Lax et al, 2017), soil (Hoch et al, 2019;Joyner et al, 2019), and sewage (Fresia et al, 2019;Maritz et al, 2019), among others. However, these efforts for the most part have only been profiled with comprehensive metagenomic methods in a few selected cities on a limited number of occasions.…”

Green Roof Research in North America: A Recent History and Future Strategies

“…that influence the richness of species found therein (Aloisio et al 2017). In addition, other aspects of diversity such as types and amount of microbial assemblages, which offer plants many protections against stressors (Fulthorpe et al 2018;Hoch et al 2019), should be fully examined. Lastly, attention should be given to the genetic diversity of green roof organisms to better determine the role these structures may play in conservation.…”