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Bee Research on Green Roofs in Asia, Europe, and North America by Michaela Hofmann and Susanne S. Renner

March 7, 2018 at 5:34 pm

A Personal View, by Michaela Hofmann

When you grow up on a farm, moving into a big city like Munich (with 1.5 million inhabitants) can feel like moving into a concrete desert.  However, only at first glance.

Between building fronts and paved roads, nature has gained a foothold.  But it was only when I began working on urban bees for my doctoral research that I became aware of a huge additional green space in modern cities, namely rooftops.

 Bee Research Green Roofs Asia Europe North America Hofmann Renner

One of the nesting aids that the researchers were trying out on the ground. Such sand heaps (even much smaller ones) would be a huge help for bees. Photo by Michaela Hofmann.

It is now mandatory for many types of buildings to have green roofs, and the aesthetic and climate benefits of this type of new urban habitat are obvious and well-documented.  But are there benefits for wild bees, the topic of my research?

The literature about effects of green roofs on biodiversity is surprisingly limited.  My search for studies about wild bees on green roofs in Asia, Europe and North America revealed that so far, only 35 studies (worldwide) have been carried out, which have identified 236 species that use man-made green roofs as foraging or nesting ground.  For comparison, there are 19,700 known bee species, and Germany alone has over 570 species.

The percentage of cavity-nesting bees on roofs is higher than that on nearby ground, while the percentage of pollen specialists is lower.  Data are almost completely lacking on the reproductive success of bees on green roofs, the effect of roof age on bee diversity, and the genetic or demographic benefits of increased habitat connectivity.

I am hoping that my list of the bee species so far reported on green roofs may help in the selection and implementation of suitable soils, nesting aids, and plantings. One reason for why green roofs are so important for insects, certainly in Germany, is that they receive less fertilizer, fewer pesticides, and fewer herbicides than most other urban and agricultural land.

I think this aspect may make green roofs scientifically interesting spaces to study the relative effects of different factors that contribute to the loss of insect diversity in Central Europe.

Bee species recorded between 1992 and 2017 from green roofs in Asia, Europe, and North America, with key characteristics and open research questions

By Michaela Hofmann* and Susanne S. Renner*
Systematic Botany and Mycology, Faculty of Biology, University of Munich (LMU)
*Joint corresponding authors

Publisher’s Note: The following article was reviewed by and posted on Apidologie 49(1): 00-00. DOI: 10.1007/s13592-017-0555-x on December 19, 2017

Bee Research Green Roofs Asia Europe North America Hofmann Renner

A male Lasioglossum calceatum discovered on green roofs. Photo by Michaela Hofmann.

Abstract

Green roofs, which have become mandatory on new flat-topped buildings in many cities, increase habitat connectivity for wildlife and have contributed to a boom in urban bee keeping.  The ecological benefits or risks of green roofs for wild bees (bee species other than the domesticated honey bee, Apis mellifera), however, have not been comprehensively analyzed.

We therefore reviewed studies on insects caught on green roofs in Asia, Europe, and North America between 1992 and early 2017 and extracted information on wild bees.  The resulting species list includes 236 Apidae identified in 35 studies, with thermophilic species probably overrepresented because roofs provide warm and dry habitats.

The percentage of cavity-nesting bees on roofs is higher than on nearby ground, while the percentage of pollen-specialists is lower.  Data are almost completely lacking on the reproductive success of bees on green roofs, the effect of roof age on bee diversity, and the genetic or demographic benefits of increased habitat connectivity.  Our list of the bee species so far reported on green roofs will help in the selection and implementation of suitable soils, nesting aids, and plantings.

 Bee Research Green Roofs Asia Europe North America Hofmann Renner

Osmia caerulescens recorded on green roofs. Photo by Michaela Hofmann.

INTRODUCTION

The past 20 years have seen a dramatic increase in research on green roofs (reviewed in Bowler et al. 2010; and Blank et al. 2013), which are now mandatory on flat-topped buildings in Switzerland and a few other European countries, and supported by incentives in the United States (Brenneisen 2006; Stutz 2010).  Although there are different types of green roofs, one can generally distinguish between intensive and extensive roof greening.

Intensive green roofs usually have a soil layer of at least 15 cm and sometimes up to 60 cm or more (Mann 1994), while extensive green roofs have only a thin layer of soil (5 -15 cm), supporting mostly mosses, herbs, succulents, and grasses (Gedge and Kadas 2005).  Roofs with shallow soil layers are a difficult growing environment for plants because of moisture stress, severe drought, and full exposure to sun and wind (Schneider and Riedmiller 1992; Dunnett and Kingsbury 2008). On the other hand, extensive roofs require minimal maintenance and can be self-sustaining.

Ecosystem services from green roofs include stormwater management (Getter and Rowe 2008; Berndtsson 2010), moderation of the urban heat island effect (Takebayashi and Moriyama 2007; Tabares-Velasco et al. 2012), lower building temperatures (Oberndorfer et al. 2007), and a role as urban wildlife habitat (for reviews see Fernandez-Canero and Gonzalez-Redondo 2010; Williams et al. 2014; Gonsalves 2016).  An important aspect for the latter role is that green roofs are undisturbed by humans during most of the year, making them quiet habitats with low pesticide loads (Hui and Chan 2011).  They also increase habitat connectivity for certain arthropods (Braaker et al. 2014).

Of the many arthropods living on green roofs, bees stand out because of their role as pollinators and because urban beekeepers tend to find bee keeping “restorative and empowering” (Moore and Cost 2013).  While urban bee keeping has led to an increase of the density of honey bees in cities, the past 50 years have seen a decline in the abundance of wild bee species, attributed mostly to habitat loss and pesticides (Goulson et al. 2008), although data on change in bee abundances in urban spaces over time are scarce.  Wild bees, most of which are solitary bees, are expected to benefit from the newly created habitat on green roofs because they may be able to forage both on the ground and on green roofs, and thermophilic species might also find nesting opportunities on green roofs.

Surprisingly, however, the effects of green roofs on the diversity and abundance of wild bees in cities have received little attention despite repeated calls for bee-targeted green roof research (Zurbuchen and Müller 2012; Witt 2016).  We here provide the first list of bee species recorded from green roofs, summarize key ecological traits of these bees, and point to important open questions about the role of green roofs as habitat for solitary bees.

Bee Research Green Roofs Asia Europe North America Hofmann Renner

A female Bombus sylvarum, found on green roofs in France. Photo by Michaela Hofmann.

Online Supporting Materials

Download the 26-page Hofmann-Renner 2017 Bee Research on Green Roofs PDF of Online Supporting Materials, Tables S1 (Table S1: Overview of green roof (= GR) studies involving wild bee species assessment-), S2 (Table S2: Alphabetical list of species reported on green roofs), and References.

 Bee Research Green Roofs Asia Europe North America Hofmann Renner
More Info

For more information and to read the entire study, you may purchase the Bee species recorded between 1992 and 2017 from green roofs in Asia, Europe, and North America, with key characteristics and open research questions PDF on Apidologie for $39.95, or contact the authors below.


~ Michaela Hofmann and Susanne S. Renner, 
Systematic Botany and Mycology, Faculty of Biology, University of Munich (LMU)

Our research focuses on the systematics, phylogenetics, and evolution of plants and fungi, especially their adaptation to biotic and abiotic factors. Methods brought to bear on these questions range from light and electron microscopy to molecular cytogenetics, field work, and next generation sequencing of entire genomes to study them comparatively.

Contact Michaela Hofmann, Systematic Botany and Mycology, Faculty of Biology, University of Munich (LMU), 80638, Munich, Germany at: michaela.hofmann@campus.lmu.de.

Contact Professor Dr. Susanne Renner, Faculty of Biology, University of Munich (LMU) at: renner@lmu.de.

Greenroofs.com Project of the Week for March 5, 2018: Dubai Opera Garden Green Roof & Greenwalls

March 5, 2018 at 2:50 pm

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Dubai Opera Garden Green Roof & Greenwalls
Dubai, United Arab Emirates
32,292 sf greenroof & vegetated terraces and approximately 500 sf greenwalls

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Greenroofs.com Project of the Week: March 5, 2018

Following our wonderful experience attending the 5th International Green Roof Congress in Kuwait City last month, we are highlighting one of the projects we visited afterwards when we traveled to Dubai: the beautiful Dubai Opera and its new Opera Garden.

Installed in July 2017, the Dubai Opera Garden has center stage to the Burj Lake and the fabulous Dubai Music Fountains presented by the stunning Burj Khalifa, currently the world’s highest building.

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Mini Description & Details

Situated in what is considered ‘the most prestigious square kilometre in the world’, the spectacular Dubai Opera is framed by the Burj Khalifa, lakes, fountains, and an array of mixed-use development.  Shaped like a dhow, a traditional wooden sailing vessel used in Arabian Gulf waters, the Dubai Opera was designed by ATKINS.

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

The 3,000 square meter Dubai Opera Garden green roof was installed by AGCCIC over a large utility building located directly in front after two years of research by Knauf Insulation. Many festivities are held here at the publicly accessible green roof park and cultural space.

Challenges included weight restraints of the roof structure, the hot and dry environment, and high water consumption for keeping the roof green.

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Knauf Insulation provided a lightweight system created by using only a 10 centimeter growing media profile using one layer of Urbanscape Green Roll mineral growing media (known as Hydro Blanket in the US) and a layer of local sweet soil on top.

Two types of semi-intensive green roofs include the large, open green park space planted with native Paspalum Grass and a smaller slightly elevated roof for plant testing with Sesuvium and others.  The system weight was reduced by 70% and irrigation needs were lowered up to 40% as compared to the standard green roof solution in Dubai.

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

More

Steps provide entry to the new green roof with access ramps on the side, dramatically lighted at night. A series of colorful modular greenwalls cover two sides to soften the structure.

Surrounded by a set of curvaceous vegetated terraces, a variety of different climate-adapted shrubs were planted such as Agave and Bougainvillea. The open space provides a beautiful elevated view of the world famous Dubai Music Fountains and colorful light show put on several times nightly.

Dubai Opera is a definitive international destination for performing arts, and its Opera Garden provides a needed and spacious public greenspace amenity to visitors to the world-class entertainment venue.

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Year: 2017
Owner:
EMAAR Properties
Location:
Dubai, United Arab Emirates
Building Type:
Commercial
Type:
Semi-Intensive
System:
Single Source Provider
Greenroof Size:
32,292 sq.ft. and Greenwalls Size: ~ 500 sq.ft.
Slope:
2% and 95%
Access:
Accessible, Open to Public

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Designers/Manufacturers of Record:

Landscape Design: Harold Bekker, NLME Design
Landscape Design: Patrick Blom, NLME Design
John Noordam: BVB Substrates
Mineral Growing Media: Urbanscape Green Roll (Hydro Blanket), Knauf Insulation
Jure Sumi: Knauf Insulation Green Solutions
Darja Majkovic: Knauf Insulation Green Solutions
Dubai Opera Architect: Janus Rostock, ATKINS
Green Roof Installation: AGCCIC
Modular Greenwall System: Biotecture Ltd
Greenwall Installation: Acacia LLC (part of Tanseeq Investments group of companies)

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

All the Info:

View the Dubai Opera Garden Green Roof & Vegetated Terraces and Dubai Opera Garden Greenwalls project profiles to see ALL of the Photos and Additional Information about these particular projects in The International Greenroof & Greenwall Projects Database.

Greenroofs.com Project Week Dubai Opera Garden Green Roof Greenwalls

Project of the Week Video Feature

Watch the Dubai Opera Garden Green Roof & Greenwalls Project of the Week Video below or see it on our GreenroofsTV channel on YouTube:

Greenroofs.com Project of the Week 3/5/18 video credits: Video courtesy of Linda S. Velazquez and photos © courtesy of Knauf Insulation/Urbanscape® Green Roof, Dubai Opera, EMAAR Properties, dubaimetro.eu, AntonGots.com, and Linda S. Velazquez.

Did we miss your contribution? Please let us know to add you to the Dubai Opera Garden Green Roof & Vegetated Terraces and Dubai Opera Garden Greenwalls profiles.

Would you like one of your projects to be featured on Greenroofs.com? We have to have a profile first! Submit Your Project Profile.

Love the Earth, Plant a Roof (or Wall)!

By Linda S. Velazquez, ASLA, LEED AP, GRP
Greenroofs.com Publisher & Greenroofs & Walls of the World™ Virtual Summits Host

Take Advantage of Grey to Green 2018’s Early Bird Rates and Save $100, by GRHC

March 2, 2018 at 1:36 pm

Grey to Green Conference // greytogreenconference.org
Green Infrastructure: Jobs, Health & Community Resilience

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

Take advantage of our early bird rates and save $100

Brought to you by Green Roofs for Healthy Cities, the 6th Annual Grey to Green Conference is taking place on May 15-16, 2018 at the Chestnut Conference Centre in Toronto.  Grey to Green focuses on green infrastructure design, research and policy and connects professionals working to integrate natural elements into the built environment.

The 2018 agenda features a wide variety of innovative content on stormwater management, urban agriculture, biophilic design, green infrastructure and the Internet of Things, and designing green communities.

Grey to Green 2018 Agenda

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

Grey to Green commences with a FREE public forum on May 15th at Toronto Metro Hall to discuss Designing Future Cities with Green InfrastructureSteven Peck, the Founder and President of Green Roofs for Healthy Cities, will kick off the night with an industry update and speak to the ever increasing need to adopt green infrastructure in our cities before introducing the events panelists.

Architect Tye Farrow, a senior partner at Farrow Partners, envisions transforming the Bloor Viaduct into a “Living Bridge” complete with individual housing suites, restaurants, hotels as well as pedestrian and bike paths.  Claire Nelischer from the Ryerson University City Building Institute shares her research findings on the need for the Rail Deck Park, a proposed 21-acre park in downtown Toronto that would be built overtop of the rail corridor between Blue Jays Way and Bathurst Street.

As designers and researchers continue to intrigue the region with futuristic projects, Grey to Green also highlights the importance of green infrastructure policy to the success and continued growth of the industry.  Deborah Martin-Downs, the CAO of Credit Valley Conservation and Chair of the Green Infrastructure Ontario Coalition, will discuss new policy developments that facilitate green infrastructure investment in Ontario.

Thought Leadership

The bulk of Grey to Green will take place on Wednesday May 16th showcasing a lineup of speakers that are leading the way for green infrastructure adoption and widespread implementation.  These thought leaders and change agents will give you exclusive access into their design processes, research findings and policy developments that will no doubt be part of our future urban fabric.

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

Don’t miss the Afternoon Keynote featuring Craig Applegath, Founding Principal of DIALOG’s Toronto Studio who will present Addressing Climate Change through Green Infrastructure and Paul Kephart, Principal, Ecologist and Designer at Rana Creek Design, as he talks about San Francisco’s Transbay Terminal Center Rooftop Park as well as discussing the work on the JNBY Headquarters Rooftop Tea Production in Hangzhou, China.

The concurrent sessions explore trends in urban agriculture, green walls, rain gardens, green roof research findings, biophilic design and stormwater management all under the theme of building resilient communities.

Save $100 on registration when you sign up before March 29, 2018!

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

Training Courses & Tours

Grey to Green will also feature a variety of training courses on May 15th such as Biophilic Design, Introduction to Rooftop Urban Agriculture, Green Roof Design & Installation and Green Walls 101.  To top off the event we have also curated an array of tours to highlight Toronto’s outstanding green infrastructure projects.

Explore Toronto’s East End that has been reinvigorated with green infrastructure design, get your boots dirty with a bus tour of the Gro-Bark mulch production plant and tour the Ryerson Rooftop Farm!  Register for tours and training courses at greytogreenconference.org.

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

Register now as early bird rates end March 19, 2018

Grey to Green Conference is pending approval for up to 7.5 Continuing Education / Professional Development Hours by LA CES, AIA CES, BOMI, APLD and RCI.

To register, visit greytogreenconference.org.

~ Green Roofs for Healthy Cities

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

Can’t make Grey to Green 2018CitiesAlive 2018 is currently accepting proposals until March 11, 2018. Visit citiesalive.org for details.

Green Roofs for Healthy Cities (GRHC)

Take Advantage GreytoGreen 2018 Early Bird Rates Save $100

GRHC’s mission is to increase the awareness of the economic, social and environmental benefits of green roofs and green walls, and other forms of living architecture through education, advocacy, professional development and celebrations of excellence.

Visit www.greenroofs.org for more information.

Contact Steven Peck, GRHC founder and president at speck@greenroofs.org and 416-971-4494 x 233.

CitiesAlive NYC 2018 Call for Proposals Due March 11

February 13, 2018 at 3:22 pm

Green Roofs for Healthy Cities’ 2018 CitiesAlive will be held in New York City

CitiesAlive NYC 2018 Call for Proposals Due March 11

Presented by Green Roofs for Healthy Cities (GRHC), the CitiesAlive®: Annual Green Infrastructure Conference will take place in Brooklyn, New York on September 24-28.  Would you like to speak or present a workshop this year?

Call for Proposals Due March 11

As Corporate Members and perennial Media Partners, we at Greenroofs.com are sharing the GRHC Proposal specifics:

Now in its 16th year, CitiesAlive, hosted by Green Roofs for Healthy Cities, explores the most recent green infrastructure science, economic valuation, asset management, public policy developments, new technology, and best practices in design, installation, and maintenance. The goal is to help inform the current policy debate by making the case for a rapid and significant increase in green infrastructure investment. 

GRHC is looking for motivating and informative presentations and interactive workshops highlighting the following areas: 

  • Climate Change Mitigation and Adaptation
  • Best Practices for Shoreline Protection
  • Urban Agriculture and Food Production
  • Human Health and Biophilic Benefits
  • Economic Benefits – Green Infrastructure Accounting & Asset Management
  • Best Practices for Bioswales Design and Management
  • Stormwater Management (Policies, Quantification, Design)
  • Energy Benefits / Urban Heat Island
  • Urban Forestry Best Practices
  • Green Wall Design and Best Practices
  • Green Infrastructure Monitoring and Management using the Internet of Things
  • Green Infrastructure and Social Equity and Social Justice
  • Monetizing the Benefits of Green Infrastructure
  • Black Arts and the Best Practices for Waterproofing in the New York Area
  • Green Infrastructure and Extreme Weather in a Changing Climate
  • Green Roof Myth Busting
  • Green Infrastructure and Policy Change
  • Biodiversity and Wildlife on Green Roofs
  • Skyrise Greening

CitiesAlive NYC 2018 Call for Proposals Due March 11

Please visit the CitiesAlive Conference website for complete information, and the Call for Proposals to submit yours!

By Linda S. Velazquez, ASLA, LEED AP, GRP
Greenroofs.com Publisher & Greenroofs & Walls of the World™ Virtual Summits Host