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

Walker, Emily A.; Lundholm, Jeremy

doi:10.1111/1365-2664.12970

Cited by 21 publications

(18 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The extensive green roof environment can be highly stressful for plants, as they are exposed to wind and high irradiance, large temperature fluctuations, low substrate water availability, and shallow substrate depths (<20 cm; Dunnett 2010, Walker andLundholm 2017). Consequently, green roofs are often planted with succulent species such as Sedum species, which are shallow rooted and very drought tolerant due to water storage in their fleshy leaves and/or stems (Sayed 2001, Durhman et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Relationships between plant drought response, traits, and climate of origin for green roof plant selection

Arndt

Farrell

2018

Ecological Applications

View full text Add to dashboard Cite

The ideal species for green or vegetated roofs should have high water use after rainfall to maximize stormwater retention but also survive periods with low water availability in dry substrates. Shrubs have great potential for green roofs because they have higher rates of water use, and many species are also drought tolerant. However, not all shrub species will be suitable and there may be a trade-off between water use and drought tolerance. We conducted a glasshouse experiment to determine the possible trade-offs between shrub water use for stormwater management and their response to drought conditions. We selected 20 shrubs from a wide range of climates of origin, represented by heat moisture index (HMI) and mean annual precipitation (MAP). Under well-watered (WW) and water-deficit (WD) conditions, we assessed morphological responses to water availability; evapotranspiration rate (ET) and midday water potential (Ψ ) were used to evaluate species water use and drought response. In response to WD, all 20 shrubs adjusted their morphology and physiology. However, there were no species that simultaneously achieved high rates of water use (high ET) under WW and high drought tolerance (low Ψ ) under WD conditions. Although some species which had high water use under WW conditions could avoid drought stress (high Ψ ). Water use was strongly related to plant biomass, total leaf area, and leaf traits (specific leaf area [SLA] and leaf area ratio [LAR]). Conversely, drought response (Ψ ) was not related to morphological traits. Species' climate of origin was not related to drought response or water use. Drought-avoiding shrubs (high Ψ ) could optimize rainfall reduction on green roofs. Water use was related to biomass, leaf area, and leaf traits; thus, these traits could be used to assist the selection of shrubs for stormwater mitigation on green roofs. The natural distribution of species was not related to their water use or drought response, which suggests that shrubs from less arid climates may be suitable for use on green roofs. Selecting species based on traits and not climate of origin could both improve green roof performance and biodiversity outcomes by expanding the current plant palette.

show abstract

Section: Introductionmentioning

confidence: 99%

Relationships between plant drought response, traits, and climate of origin for green roof plant selection

Arndt

Farrell

2018

Ecological Applications

View full text Add to dashboard Cite

show abstract

“…Substrate depth is closely linked to the green roof type, with intensive roofs usually carrying deeper substrates than extensive roofs. Deep substrates support a richness of vascular plants and arthropods [61][62][63][64], as they dehydrate more slowly than shallow substrates [65]. Exceptions to this pattern exist [66,67], for example with effects of substrate depth on plant species richness varying across time [68].…”

Section: Roof Characteristics Species Richness Species Abundance Funcmentioning

confidence: 99%

“…Generally, an increase in roof habitat heterogeneity should support species richness, at least by reducing species mortality [63]. To increase heterogeneity, Walker and Lundholm [634 suggest adding logs and pebble piles, Grant [74] and Madre et al [50] suggest increasing vegetation structural diversity.…”

Section: Roof Characteristics Species Richness Species Abundance Funcmentioning

confidence: 99%

“…Again, functional traits play a role, with succulent Sedum and also moss species thriving in shallow substrates but other (mainly non-succulent but also Sedum species [86]) species (e.g., grasses) gaining in dominance with increasing substrate depth [61,64]. Consequently, overall plant abundance increases with substrate depth [62,63,70,87] as it does with irrigation [71] and shade [88,89], i.e., favorable conditions. Increased vegetation cover and height, in turn, affect arthropods, with species such as bees that mainly prefer open, sunny sites decreasing in abundance but species such as many spiders that hunt within vegetation increasing in abundance [73].…”

Section: Trends In Green Roof Species Abundancementioning

confidence: 99%

See 1 more Smart Citation

Biodiversity Impact of Green Roofs and Constructed Wetlands as Progressive Eco-Technologies in Urban Areas

2019

View full text Add to dashboard Cite

The total amount of sealed surfaces is increasing in many urban areas, which presents a challenge for sewerage systems and wastewater treatment plants when extreme rainfall events occur. One promising solution approach is the application of decentralized eco-technologies for water management such as green roofs and constructed wetlands, which also have the potential to improve urban biodiversity. We review the effects of these two eco-technologies on species richness, abundance and other facets of biodiversity (e.g., functional diversity). We find that while green roofs support fewer species than ground-level habitats and thus are not a substitute for the latter, the increase in green roof structural diversity supports species richness. Species abundance benefits from improved roof conditions (e.g., increased substrate depth). Few studies have investigated the functional diversity of green roofs so far, but the typical traits of green roof species have been identified. The biodiversity of animals in constructed wetlands can be improved by applying animal-aided design rather than by solely considering engineering requirements. For example, flat and barrier-free shore areas, diverse vegetation, and heterogeneous surroundings increase the attractiveness of constructed wetlands for a range of animals. We suggest that by combining and making increasing use of these two eco-technologies in urban areas, biodiversity will benefit.

show abstract

“…Green roof studies have previously targeted the enhancement of species diversity via heterogeneity. Previous studies have manipulated different substrate features (Lundholm, 2009) as well as the mixing of annuals with perennials (Vasl, Shalom, Kadas, & Blaustein, 2017), creating heterogeneous surface features such as logs and pebbles (Walker & Lundholm, 2017) and substrate depth (Heim & Lundholm, 2014).…”

mentioning

confidence: 99%

Fine‐scale substrate heterogeneity in green roof plant communities: The constraint of size

Vasl

Schindler

Kadas

et al. 2019

Ecology and Evolution

View full text Add to dashboard Cite

Heterogeneity–diversity relationship (HDR) is commonly shown to be positive in accordance with classic niche processes. However, recent soil‐based studies have often found neutral and even negative HDRs. Some of the suggested reasons for this discrepancy include the lack of resemblance between manipulated substrate and natural settings, the treated areas not being large enough to contain species' root span, and finally limited‐sized plots may not sustain focal species’ populations over time. Vegetated green roofs are a growing phenomenon in many cities that could be an ideal testing ground for this problem. Recent studies have focused on the ability of these roofs to sustain stable and diverse plant communities and substrate heterogeneity that would increase niches on the roof has been proposed as a method to attain this goal. We constructed an experimental design using green roof experimental modules (4 m2) where we manipulated mineral and organic substrate component heterogeneity in different subplots (0.25 m2) within the experimental module while maintaining the total sum of mineral and organic components. A local annual plant community was seeded in the modules and monitored over three growing seasons. We found that plant diversity and biomass were not affected by experimentally created substrate heterogeneity. In addition, we found that different treatments, as well as specific subplot substrates, had an effect on plant community assemblages during the first year but not during the second and third years. Substrate heterogeneity levels were mostly unchanged over time. The inability to retain plant community composition over the years despite the maintenance of substrate differences supports the hypothesis that maintenance of diversity is constrained at these spatial scales by unfavorable dispersal and increased stochastic events as opposed to predictions of classic niche processes.

show abstract

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

Cited by 21 publications

References 37 publications

Relationships between plant drought response, traits, and climate of origin for green roof plant selection

Relationships between plant drought response, traits, and climate of origin for green roof plant selection

Biodiversity Impact of Green Roofs and Constructed Wetlands as Progressive Eco-Technologies in Urban Areas

Fine‐scale substrate heterogeneity in green roof plant communities: The constraint of size

Contact Info

Product

Resources

About