#TBT: Bee Research on Green Roofs in Asia, Europe, and North America

The function of #TBT Throwback Thursday is “Bee research on green roofs in Asia, Europe and North America”

By Michaela Hofmann and Susanne S. Renner – Originally posted on Greenroofs.com on March 7, 2018

Editor’s Note: We felt this article was a perfect fit with our #TBT series to continue the discussion on green roofs and biodiversity, especially with pollinators. Read also : Global Synthetic Roofing Underlayment Industry 2020-2025 Market Size, Growth, Trends and Forecasts – NeighborWebSJ. About a week ago we reported on how the European Parliament is calling for a green roof[s] Objectives to restore urban biodiversity.

Employees of the EU branch of the World Green Infrastructure Network (WGIN) informed that the European Parliament has passed the resolution “EU 2030 Biodiversity Strategy: Bringing nature back into our livesfully endorse the European Commission’s strategy to tackle the current biodiversity crisis in Europe and around the world.

To enjoy!

A personal view, by Michaela Hofmann

Growing up on a farm, moving to a big city like Munich (population 1.5 million) can feel like moving to a concrete desert. On the same subject : Global Roofing Adhesives Market (2020 to 2026) – Growth, Trends, COVID-19 Impact and Forecasts – ResearchAndMarkets.com. However, only at first glance.

Nature has gained a foothold between facades and paved roads. But it wasn’t until I started working on urban bees for my PhD research that I became aware of a huge extra green space in modern cities, namely roofs.

bee research

One of the nesting tools the researchers tried on the ground. Such mounds of sand (even much smaller ones) would be a huge help to 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 clear and well documented. But are there any benefits to wild bees, the subject of my research?

The literature on the effects of green roofs on biodiversity is surprisingly limited. My search for studies of wild bees on green roofs in Asia, Europe and North America revealed that only 35 studies (worldwide) have been conducted to date, identifying 236 species that use artificial green roofs as foraging or breeding area. By comparison, there are 19,700 known bee species, and Germany alone has more than 570 species.

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

I hope my list of bee species reported on green roofs so far can help with the selection and implementation of suitable soils, nesting aids and plantings. One reason green roofs are so important to insects, especially in Germany, is that they receive less fertilizer, fewer pesticides and fewer herbicides than most other urban and agricultural lands.

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

To see also :
We’ve tried to send a notification to your email address, but we’re…

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

By Michaela Hofmann* and Susanne S. See the article : Roofing Software Market: Growth, Revenue, Business Outlook & Forecast 2021-2027 | Download Sample Report – KSU. Renner*
Systematic Botany and Mycology, Faculty of Biology, University of Munich (LMU)
*Joint Corresponding Authors

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

bee research

A man wasp shoes found on green roofs. Photo by Michaela Hofmann.

On the same subject :
Global growth of the PVC roofing market in the period 2020-2025 |…

Abstract

This may interest you :
BOSTON – A New Hampshire roofer was charged in federal court in…

Green roofs, which have become mandatory on new flat-roof buildings in many cities, are increasing the connectivity of wildlife habitats and have contributed to a boom in urban beekeeping. The ecological benefits or risks of green roofs for wild bees (bee species other than the domestic honeybee, Apis mellifera), however, have not been fully analysed.

That’s why we reviewed studies on insects caught on green roofs in Asia, Europe and North America between 1992 and early 2017, and collected information on wild bees. The resulting species list includes 236 Apidae identified in 35 studies, with thermophilic species likely being overrepresented as roofs provide warm and dry habitats.

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

bee research

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

INTRODUCTION

Over the past 20 years, research on green roofs has increased dramatically (reviewed in Bowler et al. 2010; and Blank et al. 2013), which are now mandatory on flat buildings in Switzerland and some other European countries, and supported by incentives in the United States (Brenneisen 2006; Stutz 2010). Although there are different types of green roofs, a distinction can generally be made between intensive and extensive green roofs.

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 soil layer (5-15 cm), on which mainly mosses, herbs, succulents and grasses (Gedge and Kadas 2005). Roofs with shallow soil layers are a difficult growing environment for plants due to moisture stress, severe drought, and full sun and wind exposure (Schneider and Riedmiller 1992; Dunnett and Kingsbury 2008). On the other hand, extensive roofs require minimal maintenance and can be self-sufficient.

Green roof ecosystem services include stormwater management (Getter and Rowe 2008; Berndtsson 2010), mitigation 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 for 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 that live on green roofs, bees stand out for their role as pollinators and because urban beekeepers often find beekeeping “restorative and invigorating” (Moore and Cost 2013). While urban beekeeping has led to an increase in urban honeybee density, the abundance of wild bee species has declined over the past 50 years, mainly attributed to habitat loss and pesticides (Goulson et al. 2008), although data on changes in the amount of bees 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 as they can forage on both the ground and on green roofs, and thermophilic species can 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-focused research on green roofs (Zurbuchen and Müller 2012; Witt 2016). We provide here the first list of bee species recorded from green roofs, summarize the main ecological characteristics of these bees and point out important open questions about the role of green roofs as habitat for solitary bees.

bee research

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

Online Support Material

Comments are closed.