Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof

Buckland-Nicks, Michael; Heim, Amy; Lundholm, Jeremy

doi:10.1016/j.scitotenv.2016.02.063

Cited by 33 publications

(25 citation statements)

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“…The substrate and vegetation layers are the most important components determining water and heat fluxes on green roofs (Buckland‐Nicks et al, 2016). In this study, without detracting from the important role that vegetation has on the hydraulic and thermal performance of a green roof, we focused on green roof substrates.…”

mentioning

confidence: 99%

Porous Media Characterization to Simulate Water and Heat Transport through Green Roof Substrates

Sandoval

Bonilla

Gironás

et al. 2017

Vadose Zone Journal

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Core Ideas Hydrodynamic and thermal properties of five green roof substrates were determined. Coupled heat and water transport in a hypothetical roof was simulated. The green roof substrates showed a large capacity to store and transport water. Water retention, storage, and organic matter control substrate hydraulic behavior. Green roofs integrate vegetation into buildings, thereby minimizing energy requirements and water runoff. An understanding of the processes controlling water and heat fluxes in green roofs under site‐specific climatic conditions is needed to optimize their benefits. The hydrodynamic and thermal characteristics of substrates and vegetation layers are the primary controlling factors determining water and heat fluxes on green roofs. We characterized the physical, hydrodynamic, and thermal properties of five green roof substrates. We performed coupled heat and water transport numerical simulations to assess the impact of these properties on the hydraulic and thermal performance of a hypothetical roof system. The five substrates showed a large capacity to store and transport water, while their ability to conduct heat was similar to other green roof substrates. Under unsaturated conditions, water retention, storage capacity, and organic matter (OM) content of the substrates controlled the hydraulic and thermal response of each substrate. Our simulation results show that the substrate with the best capacity to store water and to reduce the heat flux through the substrate layer was composed of perlite and peat and had large OM content (30.7%) and saturated water content (0.757 cm3 cm−3). This substrate outperformed the others, probably due to its low thermal conductivity and its large pore space. The dynamic modeling presented in this study can represent the complexity of the processes that are occurring in green roof substrates, and thus it is a tool that can be used to design the configuration of a green roof.

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confidence: 99%

Porous Media Characterization to Simulate Water and Heat Transport through Green Roof Substrates

Sandoval

Bonilla

Gironás

et al. 2017

Vadose Zone Journal

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“…Buckland‐Nicks et al. () observed mortality of adult S. bicolor and S. tridentata in the hottest parts of the same green roof and other recent work suggests the effects of high temperature may be more important in promoting mortality than drought (Savi et al., ). Our results are consistent with these in that the featureless shallow microsites had the lowest seedling densities, the highest temperatures but not the lowest moisture contents.…”

Section: Discussionmentioning

confidence: 96%

“…To account for disparity in shading, solar exposure was assessed for each quadrat by generating a georeferenced map of the green roof in ArcGIS (ArcGIS 10.2.2; Environmental Research Systems Institute, Redlands, CA) combined with the spatial coordinates for each quadrat, according to Buckland‐Nicks, Heim, and Lundholm (). The map was used to simulate incident solar radiation values (KWhr/m 2 ) per quadrat for the growing season (May–September) (Figure ).…”

Section: Methodsmentioning

confidence: 99%

Designed habitat heterogeneity on green roofs increases seedling survival but not plant species diversity

Walker

Lundholm

2017

Journal of Applied Ecology

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Urban areas benefit from the ecosystem services provided by low input green roofs. However, limited substrate depth on these green roofs creates challenging conditions for plant establishment and survival, leading to industry reliance on non‐native succulents. Through a green roof and glasshouse study, we assessed the impact of simple design modifications to the green roof surface, including redistribution of substrate and addition of logs and pebble piles, on both substrate temperature and moisture content. We added seeds of 26 native species and quantified seedling density, species richness and composition over a single growing season. Overall effects of microsite heterogeneity on species diversity were assessed using species accumulation curves. The modifications altered substrate temperature and moisture. Deep substrate (10–12 cm) and the presence of surface features reduced the temperature by 14.6°C and, while surface features had mixed effects on substrate moisture on the green roof, pebble piles slowed moisture loss during a 6‐week drought in the glasshouse. Following drought conditions, seedling density and species richness were greatest, relative to seeded controls, where substrate was deep on the green roof and where pebbles were present in glasshouse modules, despite high mortality overall. Design modifications did not result in differentiation of seedling communities among different microsite types. Species accumulation curves showed no difference in species richness between aggregates of modified vs. unaltered microsites. Synthesis and applications. Redistribution of green roof substrate and the addition of logs and pebble piles altered microsite conditions and created habitat heterogeneity on a green roof. These design modifications represent a minimalist strategy to ameliorate growing conditions, improve seedling survival and decrease species loss on shallow substrate green roofs.

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“…For example, on green roofs, building height (MacIvor, ) and local landscape composition (Braaker, Ghazoul, Obrist, & Moretti, ) were important determinants of biodiversity. Also, microhabitat factors that can increase extreme conditions, such as unique building features like roof depressions or adjacent windows, may affect biodiversity and should be considered (Buckland‐Nicks, Heim, & Lundholm, ; McIntire & Snodgrass, ). Both positive and negative effects of GI on biodiversity have been implied and documented, but no comprehensive study has quantified these effects using comparison to natural or conventional counterparts in the urban environment (Table ).…”

Section: Introductionmentioning

confidence: 99%

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

Filazzola

Shrestha

MacIvor

2019

Journal of Applied Ecology

153

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The development of buildings and other infrastructure in cities is viewed as a threat to local biodiversity and ecosystem functioning because natural habitat is replaced. However, there is momentum for implementing green infrastructure (GI), such as green roofs, wetland detention basins and community gardens, that partially offset these impacts and that benefit human health. GI is often designed to explicitly support ecosystem services, including implied benefits to biodiversity. The effects of GI on biodiversity have been rarely quantified, but research on this topic has increased exponentially in the last decade and a synthesis of the literature is needed. Here, we examined 1,883 published manuscripts and conducted a meta‐analysis on 33 studies that were relevant. We determined whether GI provides additional benefits to biodiversity over conventional infrastructure or natural counterparts. We also highlighted research gaps and identified opportunities to improve future applications. We determined that GI significantly improves biodiversity over conventional infrastructure equivalents, and that in some cases GI had comparable measures of biodiversity to natural counterparts. Many studies were omitted from these analyses because we found GI research has generally neglected conventional experimental design frameworks, including controls, replication or adequate sampling effort. Synthesis and applications. Our synthesis identified that taxa specificity is an important consideration for green infrastructure (GI) design relative to the more common measurements at the community level. We also identified that ignoring multi‐trophic interactions and landscape‐level patterns can limit our understanding of GI effects on biodiversity. We recommend further examination of species‐specific differences among infrastructures (i.e. green, conventional or natural equivalents) or using functional traits to improve the efficacy of GI implementation on urban biodiversity. Furthermore, we encourage policy makers and practitioners to improve the design of GI to benefit urban ecosystems because of the potential benefits for both humans and global biodiversity.

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Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof

Cited by 33 publications

References 34 publications

Porous Media Characterization to Simulate Water and Heat Transport through Green Roof Substrates

Porous Media Characterization to Simulate Water and Heat Transport through Green Roof Substrates

Designed habitat heterogeneity on green roofs increases seedling survival but not plant species diversity

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

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