Green Roofs and Green Walls for Biodiversity Conservation: A Contribution to Urban Connectivity?

Linking the macroclimatic niche of native lithophytic ferns and their prevalence in urban environments

PREMISE

Vertical surfaces in urban environments represent a potential expansion of niche space for lithophytic fern species. There are, however, few records of differential success rates of fern species in urban environments.

METHODS

The occurrence rates of 16 lithophytic fern species native to the northeastern USA in 14 biomes, including four urban environments differentiated by percentage of impervious surfaces, were evaluated. In addition, the natural macroclimatic ranges of these species were analyzed to test whether significant differences existed in climatic tolerance between species that occur in urban environments and species that do not.

RESULTS

Three species appear to preferentially occur in urban environments, two species may facultatively occur in urban environments, and the remaining 11 species preferentially occur in nondeveloped rural environments. The natural range of fern species that occur in urban environments had higher summer temperatures than the range of species that do not, whereas other macroclimatic variables, notably winter temperatures and precipitation, were less important or insignificant.

CONCLUSIONS

Vertical surfaces in urban environments may represent novel niche space for some native lithophytic fern species in northeastern USA. However, success in this environment depends, in part, on tolerance of the urban heat island effect, especially heating of impervious surfaces in summer.

Drivers of fungal diversity and community biogeography differ between green roofs and adjacent ground-level green space

Green roof soils are usually engineered for purposes other than urban biodiversity, which may impact their fungal communities, and in turn impact the health of plants in the urban ecosystem. We examined the drivers of fungal diversity and community composition in soil of green roofs and adjacent ground-level green spaces in three Midwestern USA cities-Chicago, Cleveland, and Minneapolis. Overall, fungal communities on green roofs were more diverse than ground-level green spaces and were correlated with plant cover (positively) and roof age (negatively) rather than abiotic soil properties. Fungal community composition was distinct between roof and ground environments, among cities, and between sampling sites, but green roofs and their immediately surrounding ground-level green space showed some similarity. This suggests dispersal limitation may result in geographic structuring at large spatial scales, but dispersal between roofs and their neighbouring sites may be occurring. Different fungal taxonomic and functional groups were better explained when roofs were classified either by depth (extensive or intensive) or functional intent of the roof design (i.e. stormwater/energy, biodiversity, or aesthetics/recreation). Our results demonstrate that green roofs are an important reservoir of fungal diversity in the urban landscape, which should be considered in future green roof design.

Contribution of Home Gardens to Sustainable Development: Perspectives from A Supported Opinion Essay

Home gardening has a long history that started when humans became sedentary, being traditionally considered an accessible source of food and medicinal plants to treat common illnesses. With trends towards urbanization and industrialization, particularly in the post-World War II period, the importance of home gardens as important spaces for growing food and medicinal plants reduced and they began to be increasingly seen as decorative and leisure spaces. However, the growing awareness of the negative impacts of agricultural intensification and urbanization for human health, food quality, ecosystem resilience, and biodiversity conservation motivated the emergence of new approaches concerning home gardens. Societies began to question the potential of nearby green infrastructures to human wellbeing, food provisioning, and the conservation of traditional varieties, as well as providers of important services, such as ecological corridors for wild species and carbon sinks. In this context. and to foster adaptive and resilient social-ecological systems, our supported viewpoint intends to be more than an exhaustive set of perceptions, but a reflection of ideas about the important contribution of home gardens to sustainable development. We envision these humble spaces strengthening social and ecological components, by providing a set of diversified and intermingled goods and services for an increasingly urban population.

The Sound of a Circular City: Towards a Circularity-Driven Quietness

The circular economy paradigm can be beneficial for urban sustainability by eliminating waste and pollution, by circulating products and materials and by regenerating nature. Furthermore, under an urban circular development scheme, environmental noise can be designed out. The current noise control policies and actions, undertaken at a source-medium-receiver level, present a linearity with minimum sustainability co-benefits. A circular approach in noise control strategies and in soundscape design could offer numerous ecologically related co-benefits. The global literature documenting the advantages of the implementation of circular economy in cities has highlighted noise mitigation as a given benefit. Research involving circular economy actions such as urban green infrastructure, green walls, sustainable mobility systems and electro-mobility has acknowledged reduced noise levels as a major circularity outcome. In this research paper, we highlight the necessity of a circularity and bioeconomy approach in noise control. To this end, a preliminary experimental noise modeling study was conducted to showcase the acoustic benefits of green walls and electric vehicles in a medium-sized urban area of a Mediterranean island. The results indicate a noise level reduction at 4 dB(A) when simulating the introduction of urban circular development actions.

Application of leaf analysis in addition to growth assessment to evaluate the suitability of greywater for irrigation of Tilia cordata and Acer pseudoplatanus

Water is the key resource in fulfilling the cooling function of plants in urban environments and needs to be supplied reliably and adequately, especially during dry periods. To avoid an unsustainable use of high-quality drinking water for irrigation, the reuse of greywater should be implemented for Green Infrastructure irrigation in the sense of the circular economy. In this study, the influence of greywater irrigation on vitality of two trees species, Tilia cordata and Acer pseudoplatanus, was determined by investigating the effect of irrigation with raw or treated greywater in comparison to municipal tap water. Plant growth parameters were measured, including leaf area, number of leaves, average leaf area and annual growth. In addition, the relative chlorophyll content was determined and image analysis was used to identify vital and necrotic leaf parts. While treatment did not affect growth after one growing season A. pseudoplatanus had significantly higher leaf necrosis (34.8%) when irrigated with raw greywater compared to treated greywater (15.5%) and tap water (5.8%). Relative chlorophyll content of T. cordata irrigated with tap water decreased over time until it was significantly lower (28.5) then the greywater treatments (34.5 and 35). Image analysis of leaves to quantify necrosis proved to be a sensitive method to quantify plant health and showed negative effects earlier than an analysis of growth. Anionic surfactants and electrical conductivity had a significant influence on plant vitality. Therefore, plant selection should take these parameters into account, when planning green infrastructure irrigated with greywater.

Optimization of green infrastructure networks based on potential green roof integration in a high-density urban area-A case study of Beijing, China

Green infrastructure network (GIN) optimization is an effective measure to reduce the landscape fragmentation caused by rapid urbanization. However, there are few targeted and practical studies of GINs in high-density urban areas with a prominent contradiction between ecological construction and land scarcity, leading to insufficient feasibility of most optimization paths as they avoid practical contradictions (scarcity of land, high cost, etc.). As an effective way to economically increase green infrastructure, green roofs have been demonstrated to provide habitats and stepping stones to increase landscape connectivity for high-mobility organisms. However, few studies have applied green roofs to GIN optimization. To address this question, a new approach to optimize GINs was proposed from the perspective of integrating potential green roofs (PGRs). A complete and feasible workflow was also established to rapidly, accurately, and cost-effectively extract PGRs, scientifically evaluate the comprehensive landscape connectivity accounting for PGR isolation factors, and practically optimize GINs according to the spatial differentiation of PGRs with high landscape connectivity. This was done by integrating high-spatial-resolution remote sensing, machine learning, morphological spatial pattern analysis, landscape index method, and a minimum cumulative resistance model. A case study in a typical high-density urban area within the Beijing Fifth Ring Road, China demonstrated the applicability and implications of the workflow. The results clearly showed that the study area had a high potential for green roof retrofitting, PGRs with high landscape connectivity could effectively improve the GINs, and the spatial differentiation characteristics of the PGR network optimization benefits provided the scientific guidance for developing targeted ecological strategies. The new approach effectively improves the scientificity and implementability of GINs. It also provides a strong reference for landscape planning and ecological construction in other high-density urban areas facing the contradiction between ecological construction and land scarcity.

Echium vulgare and Echium plantagineum: A Comparative Study to Evaluate Their Inclusion in Mediterranean Urban Green Roofs

Green roofs (GRs) are proposed to offset against numerous environmental and socio-economic concerns associated with climate change and urban sprawl. In Mediterranean urban areas, to protect and conserve biodiversity through GRs, the use of native plant species from arid environments and with shallow roots is generally recommended. In north Europe, Echium vulgare L. is widely used on GRs for its tolerance to abiotic stresses and its attractiveness for bees; unfortunately, since this species requires cold winters to induce flowering and warm wet summers for vegetative growths, its adaptability to Mediterranean GRs has been questioned. The current study is based on the hypothesis that Echium plantagineum L. can adapt better to the Mediterranean environment than E. vulgare and offer blooms to pollinators, thus providing the important urban ecosystem service (UES) of protecting entomofauna biodiversity. To compare the adaptability of E. plantagineum vs. E. vulgare, both Echium species were grown and studied on the extensive GR installed at ENEA Casaccia Research Center, in the north of Rome, Lazio, Italy. The comparative analysis of the GR performance of the two species was based on several plant-related traits, including seed morphology, rosette stage, inflorescence, flower and root-related traits, and their biological life cycle, most of them showing significant differences (for example, rosette area was 1.42-fold major in E. plantagineum than in E. vulgare). The information provided in this manuscript will be useful to update the herbarium records for conservation biology. A dramatic water stress was purposely applied in the GR before the end of the hot summer season, and while E. plantagineum faced with success the imposed dehydration (88.4% vegetation cover), E. vulgare did not (7.5% vegetation cover), presumably because of its biennial life cycle which did not allow it to complete seed maturation (only 46.9% percentage mature seeds in E. vulgare respect to 89.5% in E. plantagineum). In summary, as the main result, this work shows that in Mediterranean areas, the inclusion of E. plantagineum in seed mixes for flower meadow GRs could represent a valuable alternative to E. vulgare in temperate areas, providing a safeguard for pollinators and allowing water and energy saving.

Public Perceptions of Green Roofs and Green Walls in Tokyo, Japan: A Call to Heighten Awareness

Many cities advocate retrofitting green roofs and green walls (GRGW) to create additional green areas, especially in cramped urban areas. Yet, worldwide, only a handful of studies have evaluated the public views towards the benefits and negative issues and promotion policies of this innovative greening option. To address this gap in the literature, we conducted a survey (N = 500) of residents' opinions towards GRGW in Tokyo, a city with mandatory installation of GRGW for almost two decades. Respondents mostly agreed with the contribution of GRGW to thermal comfort, air quality, and cityscape but weakly endorsed other potential benefits. High costs as well as mosquitoes and plant litter nuisances were the most recognized negative issues. Mandatory installation was the least preferred promotion policy. Instead, respondents expected installation on public buildings and provision of installation guidance. Respondents predominantly held a "moderate" view towards both the benefits and negative issues, showing indifferent attitudes towards GRGW. Income level and housing type shaped the overall perceptions, whereas age, sex, and current living environment influenced perceptions of individual aspects. Our findings signified a need for a bottom-up strategy to heighten public awareness for the advanced development of GRGW to complement and prime the top-down mandatory installation policy.

Exploring the Integration Between Colour Theory and Biodiversity Values in the Design of Living Walls

Designing green infrastructure in cities requires vegetation that has multiple outcomes and functions, particularly using plants that have both attractive visual or aesthetic features and high biodiversity values. Plantings that have high visual appeal are more highly valued by people and increase their feeling of wellbeing. Increasing biodiversity in cities is one of the major challenges facing urban planning and design. However, balancing biodiversity and aesthetic outcomes in urban planting design is complex, and to date there are few methods that can be used to guide plant selection. To address this knowledge gap, we investigated the use of a colour theory framework for planting arrangements to see if we could design vegetation that is highly aesthetic and has high biodiversity. We did this by configuring planting combinations for living walls in Malmö, Sweden, using principles based on Johannes Itten’s colour theories. The plant combinations on each wall were graphically arranged using (1) colour analysis of each plant and (2) design of the plant species into two colour schemes: light-dark colour concept and a complementary colour concept. For each species used in the compositions we created a biodiversity classification, based on its pollination value, “nativeness” and conservation value as a cultivar; and a plant visual quality classification, based on the performance from living walls studies. The graphical colour composition and interlinked biodiversity value were then compared to designs created with randomly selected plant species. The results showed that it is possible to design a living wall based on colour theory without compromising with biodiversity outcomes, namely species richness, pollination and the nativeness of the species. The results also indicate the potential application of this design approach to deliver greater aesthetic appreciation and enjoyment from plantings. While more work is needed, this study has shown that a theoretical colour framework can be a useful tool in designing green infrastructure to improve delivery of both cultural and regulatory ecosystem services.

Small Urban Green Roof Plots Near Larger Green Spaces May Not Provide Additional Habitat for Birds

Global wildlife populations are in decline, in part, due to urbanization. However, in urban landscapes, green infrastructure such as green roofs are being created to provide habitat for wildlife. Green roof isolation, planting heterogeneity, and size can all influence wildlife biodiversity, as may the age of a green roof. When new habitat is created, wildlife use of these new habitats is expected to increase over time. To test this expectation for birds, we monitored bird activity prior to and after installation of small green roof plots on six buildings located within New York City parks. Contrary to expectations, bird activity and bird species richness did not increase after green roof plot installation, nor did they increase over a period of 4 years following installation. These unexpected results may reflect the relatively small size of the plots or the fact that the plots were on buildings located within urban parks. Bird activity and bird species richness varied widely between roofs, and the composition of rooftop bird species may have been more influenced by the characteristics of the surrounding landscapes than the presence of the green roof plots. These findings suggest that small urban green roofs within a larger and, potentially, higher quality habitat may not provide additional habitat for foraging birds. Urban green roofs have numerous ecological and environmental benefits, but the size and characteristics of landscapes surrounding a green roof need to be considered when installing green roofs as wildlife habitat.

Green Interactive Installations as Conceptual Experiments towards a New Meaning of Smart Design

Nature-based design process with its embedded concept of form that follows function can be materialized as products capable of incorporating aesthetics and functionality similar to the characteristics of its natural role models. The paper addresses the topic of green installations created through a design process that simulates nature’s smart developmental mechanisms. The aim is to create an interactive installation capable of receiving and interpreting external factors that would determine the ensemble’s behavior and influence its future development and evolution. The main challenge lies in the fact that the smart feature is often achieved by intensive use of technology, which often overshadows inventive ways in which the behavioral and aesthetic properties of the material can be reinterpreted. The interactive green installation “Modgrew” investigates the possibilities of obtaining smart features through the experimental testing of two main types of configurations. The results underline the fact that, by applying the principles of biomimetic design, technologies from different fields can be combined towards obtaining a smart product. The conclusions highlight the need for future studies cover subjects such as the efficiency of automation, the possible reconfiguration of modules, behavioral optimization over time, the identification of minimal tech alternatives and the reduction of maintenance necessities.

Lessons from New York High Line Green Roof: Conserving Biodiversity and Reconnecting with Nature

The concept of sustainable urban design has appeared in different perspectives to minimize and reduce the negative impacts of urban expansion in terms of climatic and environmental drawbacks. One of the undeniable approaches of sustainable urban design is the adoption of green urban roofs. Green roofs are seen to have a substantial role in addressing and resolving environmental issues in the context of climate change. Research investigations have indicated that green roofs have a remarkable impact on decreasing rainwater runoff, reducing the heat island effect in urban spaces, and increasing biodiversity. Nevertheless, green roofs in urban spaces as a competent alternative to nature remains a standing question. To what extent can green roofs mimic the biodiversity that is seen in nature? Moreover, to what level is this approach practical for achieving a tangible reconnection with nature, or so-called biophilia? This study attempts to discuss the essence and impact of green roofs in urban spaces based on a case study approach. The study reflected lessons from the New York High Line Green Roof regarding biophilia and biodiversity in this case study. It concludes with key lessons that can be transferred to other urban spaces with similar settings.

Evaluating and comparing the green wall retrofit suitability across major Australian cities

Urban densification continues to present a unique set of economic and environmental challenges. A growing shortage of green space and infrastructure is intrinsically linked with urban growth and development. With this comes the loss of ecosystem services such as urban heat island effects, reduction of air quality and biodiversity loss. Vertical greenery systems (VGS) offer an adaptive solution to space-constrained areas that are characteristic of dense urban areas, and can potentially improve the sustainability of cities. However, in order to promote VGS uptake, methods are required to enable systematic appraisal of whether existing walls can be retrofitted with VGS. Further, feasibility studies that quantify the potential for retrofit suitability of VGS across entire urban areas are lacking. This study established an evaluation tool for green wall constructability in urban areas and validated the assessment tool by determining the quantity of walls in five major Australian cities that could potentially have VGS incorporated into the existing infrastructure. Each wall was analysed using an exclusionary set of criteria that evaluated and ranked a wall based on its suitability to VGS implementation. Sydney and Brisbane recorded the greatest proportional length of walls suitable for VGS, with 33.74% and 34.12% respectively. Conversely, Perth's urban centre was the least feasible site in which to incorporate VGS, with over 97% of surveyed walls excluded, mainly due to the prevalence of <1 m high fence lines and glazed shopfronts. This study aimed to evaluate feasibility assessments of green wall retrofitability in highly urbanised areas with the intention of creating an analytical method that is accessible to all. This method, coupled with the promising number of feasible walls found in this study, emphasises the need for more government policy and incentives encouraging green wall uptake and could play a pivotal role in the expansion of green infrastructure and urban forestry.

Urban Integration of Green Roofs: Current Challenges and Perspectives

Green roofs (GRs) are a sustainable alternative to conventional roofs that provide multiple ecosystem services. Integrating GRs into urban areas is highly relevant considering the rapidly increasing built-up in cities. Therefore, this paper systematically and comprehensively reviews the recent literature from 2011 to 2019 on GRs to identify the challenges and perspectives related to the urban integration of GRs. The review suggests that the effectiveness of GRs in delivering ecosystem services is largely dependent on context-specific parameters such as weather conditions and existing construction or design-related parameters. Integrating GRs into urban areas can be challenging given the diversity of actors, functions, and conditions characterizing these areas. Although significant research has already been conducted on GRs, research covering more geographical locations and contexts is needed. The review points out the need to include future urbanization scenarios, such as tall buildings while analyzing the impact of GRs on ecological networks. Additionally, the review emphasizes the inclusion of urban morphological parameters alongside an analysis of the impact of GRs on microclimate regulation and air quality. In terms of social acceptance, this review points out the need to consider the temporal cycles of vegetation for noting users’ perspectives. Additionally, further research is required on the social impact of GRs, considering their influence on property prices. Lastly, the review stresses the need for more city-scale studies on the impact of GRs on ecosystem services.

Toward the Biophilic Residential Regeneration for the Green New Deal

As climate changes and species extinction accelerate, the global community focuses on Green New Deal plans to promote economic development based on environmental sustainability. The Green New Deal should encourage sustainable resilience in the environment and strengthen the community’s innate ties with natural resources and biodiversity. This study describes biophilic design for sustainable and resilient residential regeneration from the perspective of the Green New Deal, and suggests potential possibilities for these approaches on a residential regeneration scale. A case study clarifies the applicable features of biophilic design in various fields, such as architectural planning and design, technology, and services, and is subdivided according to the scale of residential regeneration (unit, building, and complex). The results of this study suggest new values for existing Green New Deal policies and contribute to the segmentation of residential regeneration projects and the expansion of related industries.

Improving the Efficiency of Green Roofs Using Atmospheric Water Harvesting Systems (An Innovative Design)

Conventional green roofs, although having numerous advantages, could place water resources under pressure in dry periods due to irrigation requirements. Moreover, the thermal efficiency of green roofs could decrease without irrigation, and the plants could get damaged. Therefore, this study aims to improve the efficiency of conventional green roofs by proposing a new multipurpose green roof combined with fog and dew harvesting systems. The analysis determined that the average water use of green roofs in the summer (in humid regions) is about 3.7 L/m2/day, in the Mediterranean regions about 4.5 L/m2/day, and in arid regions about 2.7 L/m2/day. During the dry season, the average fog potential in humid regions is 1.2 to 15.6 L/m2/day, Mediterranean regions between 1.6 and 4.6 L/m2/day, and arid regions between 1.8 and 11.8 L/m2/day. The average dew potential during the dry season in humid regions is 0.1 to 0.3 L/m2/day, in the Mediterranean regions is 0.2 to 0.3 L/m2/day, and in the arid regions is 0.5 to 0.7 L/m2/day. The analysis of the suggested multipurpose green roof combined with fog/dew harvesting systems, in the summer, in three different climates, show that fog harvesting could provide the total water requirement of the green roofs, and that dew harvesting by PV (photo-voltaic) panels could provide 15 to 26% of the water requirements. Moreover, it could show a higher thermal impact on the building, higher efficiency in stormwater management, less dependence on the urban water network, and greater efficiency in decreasing urban air, water, and noise pollution. Finally, the novel green roof system could consume less water due to the shaded area by mesh and solar PVs and maximize the utilization of the roof area, as solar panels could be applied on the same green roof.

A Novel Idea for Improving the Efficiency of Green Walls in Urban Environment (an Innovative Design and Technique)

The advantages of low-impact development approaches, such as green walls in an urban environment, are numerous. These systems can be applied for managing stormwater, saving energy consumption, decreasing noise pollution, improving runoff quality, improving life quality, and so forth. Besides, atmospheric water harvesting methods are considered a nonconventional water source. There are many studies about the analysis and advantages of green walls and atmospheric water harvesting conducted separately. However, the use of a combined system that uses fog harvesting in the irrigation of green walls has received less attention in previous studies, and therefore in this research, the feasibility of a novel green wall platform was investigated. At first, the potential of using green walls and atmospheric water harvesting in different climates was analyzed. Then a new combined system was proposed and explained. The study results determined that atmospheric water harvesting can be applied as a source of irrigation for green facilities, particularly in the dry season and in periods with lower precipitation. In the Mediterranean climate, summer fog harvesting yields 1.4–4.6 L/m2/day, and the water consumption of green walls is about 4–8 L/day/m2. This can improve one issue of green walls in an urban environment, which is irrigation in summer. Furthermore, the novel system would protect plants from severe conditions, improve buildings’ thermal behavior by decreasing direct sunlight, and increase conventional green walls’ efficiency and advantages.

Relationship between Rural Settlements’ Plant Communities and Environmental Factors in Hilly Area of Southeast China

The construction of the ecological environment in rural settlements is a very important part of the development of human settlements. Key to this construction is the coordinated and sustainable development of plant environment, geographical environment, and human activities. Therefore, it is necessary to study the characteristics of plant diversity and their driving mechanisms. The study area, ‘Shanchuan Town’, is located in the hilly area of Southeast China, Anji County, Zhejiang Province. As bamboo forests cover 62% of the total forests, it has the reputation of being the “China town of bamboo”. To interpret rural plant community features, we extracted topography data by the field survey, satellite image, and Digital Elevation Model (DEM) based on ArcGIS platform, then used Spearman’s correlation and a redundancy analysis to examine the relationships between explanatory variables (e.g., plot elevation, slope aspect and architectural height, etc.) and the distribution of plant community diversity. In this study, 227 plots were selected from 14 settlements to investigate totally 105, 88, 206, and 17 species of trees, shrubs, herbs, and vines, respectively, belonging to 147 families, 324 genera, and 416 species. Among them, there were 19 bamboo species, and 47 species of alien plants, which accounted for 11.3% of the total. The dominant trees and shrubs were mainly native species with high edible or ornamental value. The dominant bamboo species were common species for bamboo shoots in Zhejiang Province, while most of the dominant herbaceous species were alien species. Among the explanatory variables, the impact of plot elevation (PE) on plant community was significantly higher than those of other explanatory factors. The correlation analysis showed that the richness and diversity indices of different plant life layers were significantly related to PE. Among the architectural factors, the architectural orientation (AO) and layout type (AT) effect on shrubs and other herbaceous species was stronger than those on trees and bamboo. There was a high plant community richness in the study area, and both topography and architectural factors had a significant effect on plant community. Therefore, construction of the plant landscape should conform to the topography and regulate the residential construction activities properly, so as to get rid of urban planning thinking and the excessive pursuit of plant diversity, realizing the sustainable development of ecological environment in settlements.

Green roof and ground-level invertebrate communities are similar and are driven by building height and landscape context

Green roofs are increasingly promoted for urban biodiversity conservation, but the value of these novel habitats is uncertain. We aimed to test two hypotheses: (i) green roofs can support comparable invertebrate family and order richness, composition and abundances to ground-level habitats and (ii) green roofs planted with native species from local habitats will support a richer invertebrate community at family and order level than other green roofs. We sampled the invertebrate community on green roofs dominated by native grassland or introduced succulent species in Melbourne, Australia, and compared these to the invertebrate community in ground-level sites close by, and sites with similar vegetation types. The only significant differences between the invertebrate communities sampled on green roofs and ground-level habitats were total abundance and fly family richness, which were higher in ground-level habitats. Second hypothesis was not supported as invertebrate communities on green roofs supporting a local vegetation community and those planted with introduced Sedum and other succulents were not detectably different at family level. The per cent cover of green space surrounding each site was consistently important in predicting the richness and abundance of the invertebrate families we focussed on, while roof height, site age and size were influential for some taxa. Our results suggest that invertebrate communities of green roofs in Melbourne are driven largely by their surrounding environment and consequently the effectiveness of green roofs as invertebrate habitat is highly dependent on location and their horizontal and vertical connection to other habitats.

Vertical life: impact of roof height on beetle diversity and abundance on wildflower green roofs

Despite their increasing popularity in an urban setting, we still know relatively little in how well-extensive green roofs support biodiversity in terms of vertical connectivity from terrestrial habitats. Most green roof biodiversity studies have not considered whether the roof height affects community composition and abundance of species present. This study focused on evaluating beetle diversity and abundance in relation to roof height, with emphasis on wildflower roofs. The key results of the study confirm previous studies found that extensive wildflower green roofs are capable of supporting fairly rich beetle communities, including some rare/scarce species. However, an increase of roof height was found to negatively impact both beetle abundance and richness, despite all recorded species being well adapted to active flight and thus dispersal. In addition forb cover decreased with roof height which consequently influenced beetle community structure. These results are therefore indicative that further research is required on species communities found on extensive green roofs that are less adapted to active flight and consequently vertical dispersal. This study further highlights the need for vertical and horizontal connectivity between green roofs and the surrounding natural habitats as a management tool to increase the general ecological value of urban green spaces.

Green Facades and Living Walls—A Review Establishing the Classification of Construction Types and Mapping the Benefits

The green facades and living walls of vertical greenery systems (VGS) are gaining increasing importance as sustainable building design elements because they can improve the environmental impact of a building. The field could benefit from a comprehensive mapping out of VGS types, an improved classification and nomenclature system, and from linking the benefits to a specific construction type. Therefore, this research reviews existing VGS construction types and links associated benefits to them, clearly differentiating empirical from descriptive supporting data. The study adopted a scoping research review used for mapping a specific research field. A systematic literature review based on keywords identified 13 VGS construction types—four types of green facades, nine types of living walls, and ten benefits. Thermal performance, as a benefit of VGS, is the most broadly empirically explored benefit. Yet, further qualitative studies, including human perception of thermal comfort are needed. Improvements in air quality, reduction of noise, positive effects on hydrology, and visual benefits need much further empirical testing, as the current supporting data is mostly descriptive and based on the similarities with green roofs. The educational benefits of VGS has no supporting empirical evidence, while the social benefits have only been empirically evaluated through one identified study. Future progress of the field depends on the adoption of a clear VGS nomenclature system and further qualitative and quantitative empirical testing of VGS benefits, which should be clearly linked to a specific VGS construction type so that cross-comparison of studies is enabled.

Hydrological Performance of Green Roofs at Building and City Scales under Mediterranean Conditions

Green roofs are one specific type of sustainable urban drainage system (SUDS); they aim to manage runoff at the source by storing water in its different layers, delaying the hydrological response, and restoring evapotranspiration. Evidence of their performance in the Mediterranean is still scarce. The main objective of this paper is to analyse the hydrological performance of green roofs at building and city scales under Mediterranean conditions. A green roof and a conventional roof were monitored over one year in Benaguasil (Valencia, Spain). Rainfall and flow data were recorded and analysed. Hydrological models were calibrated and validated at the building scale to analyse the hydrological long-term efficiency of the green roof and compare it against that obtained for the conventional roof. Results show that green roofs can provide good hydrological performances, even in dry climates such as the Mediterranean. In addition, their influence at the city scale is also significant, given the average runoff coefficient reduction obtained.