Green Roofs - Living Architecture Monitor - Summer 2011 - (Page 5)

A EASY-TO-INSTALL WHITE NESTING BOX (PICTURED BELOW, AT RIGHT) WILL SUPPORT CAVITY-NESTING BEES. must be considered. For example, many Leafcutter bees forage widely on both native and nonnative plants, but without leaves of certain groups of plant species (this varies considerably by bee species and region) nearby, or even the green roof (this varies considerably by region) to line their brood cells in dark, dry cavities they will only have marginal success in the area, or visit infrequently. The same can be said for other cavity-nesters, like Mason bees which need bare soil and water to make mud for their nests, whereas some other bees collect tree and plant resins to line their nests. Similarly, for generalist ground-nesting bees, heterogeneity in green roof soil and vegetation composition will optimize nesting space for most species – critical for pollinator resiliency. Some species prefer sandy soils, left bare and in the sun, whereas others prefer richer soils or clay, and some even like untrampled lawns. Shallow, extensive green roofs with growing medium that dries completely in the summer, or freezes entirely during winter may not be suitable for many ground-nesting bees, but varying soil topography might encourage smaller URBAN BEES STUDY SPREADING ITS WINGS AND NEEDS YOUR HELP NORTH AMERICAN STUDY OF WILD BEES ON GREEN ROOFS SEEKING PARTICIPANTS TO HOST BEE “CONDOS” ON THEIR GREEN ROOFS IN 2012 A “Intuitively, intensive green roofs, with their greater soil depths, could support a greater diversity and abundance of ground-nesting bees.” workers, drones and often a queen (or queens) — often forage longer during the season and are more abundant. Therefore, honey bees and bumble bees, both being large and social, are most commonly observed on green roofs. However, the vast majority of bee species are solitary, with the female working to provision her offspring entirely on her own. Solitary bees may be common on florally diverse green roofs. However, most bee species nest in the ground and the suitability of green roofs for ground-nesting bees remains unstudied. However, many nest in cavities, which are small, dark and dry holes that exist in cities as raspberry canes, reeds, the brickwork of buildings, and in beetle-bored holes in both living and dead trees as well as anthropogenic (human-made) wooden ”nestboxes,” all of which can be incorporated into green roof design. Many are very common and most docile — unlike social bees quick to defend their colonies solitary bees will sting only if held. When enhancing green roof habitat for wild bee species, both forage and nesting requirements ground-nesting species, like Sweat bees and Mining bees, to nest in the areas of deeper depths. Intuitively, intensive green roofs, with their greater soil depths, could support a greater diversity and abundance of ground-nesting bees. Nesting requirements aside, a plant community that provides diversity and a long flowering period will support a wider variety of pollinator species able to reach green roofs. Identifying opportunities to create niche habitat for wild and beneficial species on green roofs is the logical next step forward in their design and integration into regional planning in support of urban biodiversity and ecosystem functions. J. Scott MacIvor is a PhD candidate at York University in Toronto, Ontario and co-research coordinator at the GRIT Green Roof Lab at the University of Toronto. He will be presenting more on green roofs and the benefits of design in support of both managed and wild bees at CitiesAlive on Friday Dec. 2nd in Philadelphia, Pennsylvania. new study in Toronto undertaken by Scott MacIvor and the Packer Lab at York University began May 2011 and aims to examine the diversity and foraging behavior of cavity-nesting bees on green roofs, and how best to integrate their presence and pollination services into green roof design and maintenance strategies. The study is using 200 bee “condos” made of small paper tubes of varying widths inside of protective casing, set up all over the city of Toronto on green roofs and at ground level. This year, the project also mailed bee condos to participants in cities across North America. Now, in hopes of expanding the project in 2012, we are asking for green roof owners, tenants, designers, managers, and the like everywhere to participate by hosting some of these bee condos. Participation consists of receiving two condos by mail (shipping and materials are covered). At the end of April 2012, participants will be asked to attach one of their new bee condos to some feature on the roof and the second, somewhere close by at ground level. Each are left alone all summer, and collected in October and sent to a central processing facility. All contents will be identiﬁed to species at the Packer Lab and from each green roof — ground level pair, an index of similarity will be calculated to compare all sites in the study. The study will be repeated for three years. With the number of green roofs increasing in cities every year, if correctly conceived, these novel habitat patches could become a unique component of strategies to sustain refuge for wild pollinators and their associated essential ecosystem functions in cities. Please contact wildbeestoronto@gmail.com, or visit www.TObee.ca for information on how to participate in this study. http://www.TObee.ca

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Summer 2011

Green Roofs - Living Architecture Monitor - Summer 2011
Contents
Water Worries
Cities Re-Imagined
Design Strategies for Wild Bees
Special Section: Cities Alive 2011 Conference Guide
Thin Flats
Sky Island at the Visionaire
Welcome New Members
New Corporate Members
Professional Calendar
Seven-Year Pitch

Green Roofs - Living Architecture Monitor - Summer 2011