Thirty years unmanaged green roofs: Ecological research and design implications

Catalano, Chiara Eva; Marcenò, Corrado; Laudicina, Vito Armando; Guarino, Riccardo

doi:10.1016/j.landurbplan.2016.01.003

Cited by 70 publications

(66 citation statements)

References 32 publications

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“…Extensively managed green roofs are dynamic systems in which it has been shown that, over the long term, biomass and taxonomic and functional diversity of colonized plant species change considerably (Dunnett, Nagase & Hallam ; Catalano et al . ). The green roofs in our study had a mean age of 13 years and consequently were mature enough, that spontaneous colonization of plants increased species richness (Brenneisen ; Catalano et al .…”

Section: Discussionmentioning

confidence: 97%

“…The green roofs in our study had a mean age of 13 years and consequently were mature enough, that spontaneous colonization of plants increased species richness (Brenneisen ; Catalano et al . ). Further, spontaneous colonization has been shown to be facilitated on green roofs with shallow substrates as more open space is available (Dunnett, Nagase & Hallam ), but of course such spontaneous colonization will only influence plant species richness if management of green roofs is kept minimal.…”

Section: Discussionmentioning

confidence: 97%

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Habitat connectivity and local conditions shape taxonomic and functional diversity of arthropods on green roofs

Braaker

Obrist

Ghazoul

et al. 2017

Journal of Animal Ecology

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Increasing development of urban environments creates high pressure on green spaces with potential negative impacts on biodiversity and ecosystem services. There is growing evidence that green roofs - rooftops covered with vegetation - can contribute mitigate the loss of urban green spaces by providing new habitats for numerous arthropod species. Whether green roofs can contribute to enhance taxonomic and functional diversity and increase connectivity across urbanized areas remains, however, largely unknown. Furthermore, only limited information is available on how environmental conditions shape green roof arthropod communities. We investigated the community composition of arthropods (Apidae, Curculionidae, Araneae and Carabidae) on 40 green roofs and 40 green sites at ground level in the city of Zurich, Switzerland. We assessed how the site's environmental variables (such as area, height, vegetation, substrate and connectivity among sites) affect species richness and functional diversity using generalized linear models. We used an extension of co-inertia analysis (RLQ) and fourth-corner analysis to highlight the mechanism underlying community assemblages across taxonomic groups on green roof and ground communities. Species richness was higher at ground-level sites, while no difference in functional diversity was found between green roofs and ground sites. Green roof arthropod diversity increased with higher connectivity and plant species richness, irrespective of substrate depth, height and area of green roofs. The species trait analysis reviewed the mechanisms related to the environmental predictors that shape the species assemblages of the different taxa at ground and roof sites. Our study shows the important contribution of green roofs in maintaining high functional diversity of arthropod communities across different taxonomic groups, despite their lower species richness compared with ground sites. Species communities on green roofs revealed to be characterized by specific trait assemblages. The study also provides details on the environmental conditions that influence arthropod diversity and gives new perspectives on how the design of green roofs can be improved to increase their ecological value. Furthermore, the study highlights the importance of integrating green roofs in planning policies which aim to enhance urban habitat connectivity.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 97%

Habitat connectivity and local conditions shape taxonomic and functional diversity of arthropods on green roofs

Braaker

Obrist

Ghazoul

et al. 2017

Journal of Animal Ecology

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“…Several substrates of varying depth and composition were tested. We applied two substrate thicknesses, of 5 cm and 15 cm, falling within the classical range for extensive green roofs found in literature [20,32,41]. Two types of material were used: (1) fine elements from quarry sludge composed exclusively of clays and silts; (2) raw materials with a particle size range of 0-30 mm and originating from Durancian gravel (known by scientists as geological material and which quarries consider exploitable deposit, screened (sorted) with minimum storage to limit recruitment of seed from undesirable species (anemochorous Asteraceae in particular).…”

Section: Experimental Protocolmentioning

confidence: 99%

“…In the case of Mediterranean green roofs, the main criteria are drought tolerance, their indigenous nature, aesthetic characteristics (to ensure acceptance by the general public) and low maintenance requirements [3,16,23,32]. Regional plant communities can thus serve as a model for the recruitment and installation of seeds on green roofs [22,32,33], being composed of stress-adapted species and ruderal species that have the capacity to maximize resources. Moreover, ecological theory suggests that diverse vegetation is more resistant and resilient to severe environmental stress.…”

Section: Introductionmentioning

confidence: 99%

Substrate Composition and Depth Affect Soil Moisture Behavior and Plant-Soil Relationship on Mediterranean Extensive Green Roofs

Chenot

Gaget

Moinardeau

et al. 2017

Water

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Abstract:The Mediterranean basin is extremely vulnerable to climate change, and one of the areas most impacted by human water demand. Yet the green roofs increasingly created both for aesthetic reasons and to limit pollution and urban runoff are themselves very water-demanding. Successful green roof installation depends on the establishment of the vegetation, and the substrate is the key element: it conserves water, and provides the nutrients and physical support indispensable for plant growth. Since typical Mediterranean plant communities require no maintenance, this study seeks to develop techniques for creating maintenance-and watering-free horizontal green roofs for public or private buildings in a Mediterranean context. The innovative aspect of this study lies in creating two soil mixes, fine elements (clay and silt) and coarse elements (pebbles of all sizes), in two different thicknesses, to assess vegetation development. Monitoring of substrate moisture was carried out and coupled with local rainfall measurements during summer and autumn. As expected, substrate moisture is mainly influenced by substrate depth (the deeper, the moister) and composition (the finer the particles (clays and silts), the higher the moisture content). Vegetation cover impacts moisture to a lesser extent but is itself affected by the composition and depth of the substrates. These results are subsequently discussed with relation to the issue of sustainable green roofs in Mediterranean climates. Considering applications of our results, for an optimal colonization of a Mediterranean vegetation, a substrate thickness of 15 cm composed mainly of fine elements (75% clay-silt and 25% pebble-sand) would be recommended in green roofs.

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“…This observed spatial and temporal variation in composition lends support to the use of networks of small, disaggregated patches of land within cities to maximise biodiversity conservation (e.g. Catalano, Marcenò, Laudicina, & Guarino, ; Goddard, Dougill, & Benton, ).…”

Section: Discussionmentioning

confidence: 67%

Land use history and seed dispersal drive divergent plant community assembly patterns in urban vacant lots

Johnson

Borowy

Swan

2017

Journal of Applied Ecology

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Abstract1. Despite high levels of disturbance and habitat modification, urban ecosystems still host substantial levels of biodiversity. The processes that maintain existing levels of diversity, however, remain understudied. Identifying the links between urban ecological processes and patterns has, therefore, become a fundamental research goal to support urban biodiversity and ecosystem functioning.2. We conducted a study to determine how the diversity and composition of urban plant communities is affected by spatially and temporally variable land use legacies.We constructed a chronosequence of vacant lot properties covering a range of 3-22 years since demolition, in an urban neighbourhood in Baltimore, Maryland (USA). Surveys of herbaceous plant species abundance were conducted during the summers of 2012 and 2013 in sections of each vacant lot where the building previously stood (the "building footprint") and sections of the lot that was previously a backyard or garden (the "remnant garden").3. We found divergent patterns in plant community composition between areas of vacant lots with varying land use histories. This includes significant shifts in the functional composition of biotically vectored seed dispersal strategies, as well as an increase in seed mass and terminal velocity trait values of plant communities in building footprints over time. In addition, we found that plant communities in different sections of the same vacant lot tended to become more functionally dissimilar in seed dispersal strategies over time. In contrast, we found no significant changes in taxonomic diversity over time for any of our measures. Policy implications.Our study suggests that regional-scale patterns of seed dispersal interact with diverse land use legacies to structure the plant communities of urban vacant lots. Although it has been suggested that highly altered local environmental conditions and competition from introduced species limit native plant diversity in urban environments, we find seed dispersal to be a more significant driver of urban plant community assembly patterns. Implementing management strategies that focus on habitat connectivity and enhancing species pools via seeding may present an effective strategy for promoting more successful establishment of diverse plant communities in urban environments. K E Y W O R D SBaltimore, community assembly, land use history, plant diversity, plant traits, seed dispersal, urban ecology, urban green space, USA, vacant lots

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Thirty years unmanaged green roofs: Ecological research and design implications

Cited by 70 publications

References 32 publications

Habitat connectivity and local conditions shape taxonomic and functional diversity of arthropods on green roofs

Habitat connectivity and local conditions shape taxonomic and functional diversity of arthropods on green roofs

Substrate Composition and Depth Affect Soil Moisture Behavior and Plant-Soil Relationship on Mediterranean Extensive Green Roofs

Land use history and seed dispersal drive divergent plant community assembly patterns in urban vacant lots

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