In my day job with NC Farm Bureau I have the opportunity to be engaged with large stakeholder groups working on topical current issues. Through that work I recently attended the First National Conference on Protecting Pollinators in Ornamental Landscapes held in mid-October in Hendersonville, NC that was organized by Michigan State University and North Carolina State University. A crowd of 183 assembled to network and to hear the latest thinking on pollinator protection in managed urban spaces. Here I’m sharing takeaways from just a few of the presenters that focused on bees and pollinator habitat.
“Yards and gardens affect pollinators.” If all the land in residential neighborhoods were added up, it’s greater than the land in parks and reserves, said Emily Minor, University of Illinois, Chicago. She studies community and landscape ecology and looks at residential neighborhoods as an ecosystem. The results of her mobile garden experiment in Chicago were enlightening. Her team observed pollinators for 60 hours on pots of cucumber, eggplant and Echinacea (3 each) placed in different residential neighborhoods for 30 days. Afterwards, pots were returned to the lab to set fruit and seed. In addition to recording 1,300 pollinator visits, they recorded the floral resources in residential front yards. One-fourth of the floral resources were native, about two thirds were ornamental. “Bees visited about half of all the blooming plants,” she said. “Neighborhoods with the highest floral diversity had the greatest abundance of bees and the greatest richness/diversity of bees.” Yards with turf had fewer bees than yards with flower gardens, she said. Socio-economic factors affect weed abundance (bees like flowering “weeds”). Weeds were documented in 55 of the 58 neighborhoods… the three yards in wealthy neighborhoods had no flowering weeds. Three variables determined more than half (51%) of the “richness of floral resources.” 1) The number of homes, 2) household income and 3) the percentage of Hispanic residents. “If floral resources are distributed based on ethnic group and income, what does it mean to pollinators?” Net/net: “People have the possibility to make a difference. We are not just limited to parks and reserves.”
Just because it flowers, doesn’t mean the pollinators will visit. The Raleigh-Durham, North Carolina area is one of the most rapidly growing regions in the US. To understand patterns of pollinator services to native plants, Rebecca Irwin, North Carolina State University, studied pollinators in suburban sites compared to wild sites in the Triangle area in and around Raleigh. Suburban sites have 50% more bees which, she says “suggests they hold conservation value for native bees.” Rebecca said flowering species richness with diverse gardens and/or diverse wilderness both support more bees. The number of rare bee species was no different in suburban or wild areas.
(A finding also supported from a recent study in the UK). Rebecca and her team’s work showed that high bee abundance does not translate into pollination services for native plants like Gelsimium sempervirens. She found that G. sempervirens in urban areas had more heterospecific pollen receipt: They get a lot of non-Gelsimium pollen from other flowers. Bees are attracted to beautiful gardens and suburban areas are good for bees and for foragers feeding on bees, she said. Suburban garden plants may even lure bees away from wild-growing plants–increased availability of a wide range of floral resources in suburban areas may make native flowers less attractive to pollinators. Just because the pollinators are there, does not mean they will pollinate all plants.
Urban Pollinators. Jane Memmott, University of Bristol, United Kingdom. Jane’s Urban Pollinator Project has a large team of 28 across four UK universities and is upending the way we look at cities for their ability to provide pollinator habitat. www.bristol.ac.uk/urban-pollinators Jane outlined a project that’s still in the works where the team is developing methods to doing to account for the whole city as a system of interconnected parts. The idea: To categorize land use and document how that affects pollinators. Sample plots (replicated) in each of 4 cities: Bristol, Reading, Edinburgh and Leeds are categoriezed by their land use, cemeteries, allotment gardens, residential gardens, road verges, pavement, nature reserves, other green space, etc. In accounting for land, railroads, water and actual roadways were excluded. They captured 7,861 insects (390 identified to the species level) and documented 641 plant taxa with 427,191 floral units. Land categories are consistent across the four cities and insect and floral data is tied to land use, getting a rating per sq. m. For instance, they discovered that “Allottments and gardens are really important,” Jane said. Allotments take a small area, but are very important, while residential gardens take up a large area, about one-third of the cities are garden, which is great for pollinators, she says. Then the team then performed a paper exercise. Using pollinator counts by area, they extrapolated to the city as a whole. Can cities improve habitat? Absolutely, yes. The best place to begin may be in “other green space,” which is huge, “but it can be better for pollinators,” Jane said. Right now “it’s mown to death, if roadsides were just mown less” their habitat value would be much higher. Changing lawn culture to “grow don’t mow.”…But we need a way that it works for people and for pollinators. If you reduce your mowing rate by 1/3, “all the weedy things people love to hate will be allowed to flower, which is great for pollinators.” Or even, she suggested, just mow a fringe around it. One member of the team has a fellowship to working with external stakeholders like planners, land managers, policymakers, conservation groups, businesses, academics and the landscape industry to help shape urban policies friendly to pollinators. Get Bristol Buzzing. Bristol Pollinator City. http://www.avonwildlifetrust.org.uk/getbristolbuzzing
Native and non-native plants can be good for bee friendly landscapes. Most of the bee lists put out today are anecdotal, said Dan Potter, University of Kentucky, who has a graduate student sampling pollinators on 55 species of flowering trees and shrubs for her Master’s degree. There’s pollinator “listmania” lots of lists, lots of books. Dan’s student, Bernadette Mach is collecting 50 bee samples from each of five sites (urban landscapes, street trees, cemeteries and urban arboreta) per plant species to take a look at bee attractiveness for a snapshot in time during peak bloom in good weather. Bernadette’s counts include both attractive and non-attractive plant species. So far she’s found that different woody ornamentals attract unique bee assemblages, such as Malus sp. (flowering crabapple) and Deutizia gracilis. Bee assemblages of some plants show high site-to-site variation, like the native Aralia spinosa. Diversity, species richness and evenness vary by plant species such as with Philadelphus sp. and Vitex agnus-castis. The top five: Rhus copallinum (winged sumac), Tetradium daniellii (bee bee tree) (Note: On an invasives watchlist in PA): Hydrangea paniculata, Cercis canadensis, and Hypericum sp.
Flower form matters: Single flowers like Rosa arkansana are good, vs. doubles like most ornamental roses, “which are useless.” But both native and non-native plants can be good for bee friendly landscapes. For instance, natives like Cercis canadensis, Cladrastis kentukea, Crategus viridis, or Ilex opaca or ornamentals like Deutzia gracilis, Vitex agnus-castis, or Pyracantha sp. The idea of the project is to help increase demand for plants that are bee friendly and relatively pest free. And if you really want to provide forage…he added, plant clover lawns and dandelions for pollinators. “If the Queen of England can tolerate clover in her lawn, why not the US?”
Maryland native plants attract good bugs/natural enemies. Here’s a great list of banker plants to put in for attracting natural enemies. On the way home from Hendersonville, I stopped off to visit an organic young plant producer (Jeff Mast at Banner Greenhouses) who was in the process of installing a “banker plant berm” to foster habitat for good bugs. This list below was shared at the meeting from 2004 published work by Steve Frank and Paula Shrewsbury based on research at the University of Maryland: Asclepias syriaca Asclepias tuberosa Coreposis verticillata Eupatorium hyssopifolium Monarda punctata Pycnanthemum tenuifolium Scutellaria integrifolia Panicum virgatum Sorghastrum nutans Schizachyrium scoparium
70% of Georgia home owners say they want to garden to protect the environment. Susan Varlamoff, University of Georgia, discovered that one snowy night she actually got 100 people to show up for a seminar on “Water Quality and Environmentally Friendly Landscaping.” Then she thought, if we have programs for buildings, like LEED, why not for home gardens? That led to the first peer-reviewed book being published by the University of Florida, Sustainable Gardening in the Southeast (2016). She covers climate change, biodiversity, water, soil health, pollinator loss, pest management, wildlife habitats, native plants and invasive species. She recommends, reduce lawn to no more than 40%. Remove non-native invasive plants and replace them with natives. And most importantly, plant a variety of native trees. http://upf.com/book.asp?id=VARLA001
Build it and they (the tourists) will come. That’s not exactly what you think of with a pollinator garden, but then you’d be underestimating the power of Debbie Roos, North Carolina State University extension agent for Chatham County. Her pollinator garden at Chatham Marketplace https://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-pollinatorgarden/ draws a diverse crowd from across the state. Visitors spend money too: 87% said they spend money shopping and eating out in Pittsboro, with an average of $96 per visitor (may include multiple visits).
Local nurseries profit too as 74% of her pollinator program participants said they bought plants at local nurseries as a result of her educational programs, spending an average of $154. Debbie is dedicated about marketing the garden on Facebook and Instagram. She also offers regular garden tours, pollinator classes and even has a Pollinator Day that draws 300-400 people. The garden features 172 plant species, most native to the North Carolina Piedmont. She wouldn’t be able to accomplish the job without a dedicated group of volunteers. Debbie is also an amazing photographer. Connect with her on Facebook or Instagram to be amazed with photographs of the pollinator visitors at the garden.
Briefly a couple of the posters:
If they don’t have a home, does food matter? “In heterogenous urban habitats, local flower quantity may not be as influential on pollinator dynamics as nesting availability,” conclude a team at the University of Michigan. Planting pollinator habitat is all the rage. But, there’s little information on the point at which more flowers begin to help or stop helping pollinators in urban landscapes. The study looked at 18 parking lots at the University of Michigan sampled every two weeks from June to August, collecting or observing 2,717 pollinators. They found pollinator abundance increases slightly with flower quantity. But they raised an even larger question overall, is flower quantity overshadowed by the availability of nesting sites?
Where the bees were in Californian urban gardens. University of California Berkeley Urban Bee Lab (http://www.helpabee.org/ ) has been monitoring California gardens to understand native and non-native plant attractiveness to bees. Together with a team member from the University of California Davis, four members of the Urban Bee Lab collected 7,569 bees from 2005 to 2011 in 10 urban gardens in California. Bees visiting 15 native plants (including cultivars) and 19 non-native plants that occurred in five or more cities were documented. Cities in the Urban Bee Lab studies go from Redding in the north to Palm Desert in the south. In this study, it’s no surprise that the Asteraceae family had the highest number bee attracting plants that were both native and non-native. Main native plant families attracting bees: Boraginaceae, Papaveraceae, Asteraceae, Rhamnaceae, Lamiaceae, Ericaceae, Polygonaceae, and Berberidaceae. Non-native plant families attracting bees: Lamiaceae, Asteraceae, Plantaginaceae, and Boraginaceae. For the Urban Bee Lab’s list of Best Bee Plants for California: http://www.helpabee.org/uploads/1/9/0/5/19051461/ubg_master_list.pdf
Top 10 natives and non-natives
Natives (# bee species) Phacelia tanacetifolia (59) Ceonothus sp. and cultivars (51) Eschschoizia californica (44) Erigeron glaucus and cultivars (37) Solidago californica (37) Salvia mellifera (33) Encelia californica (31) Eriogonaum fasciculatum (25) Achillea millefolium (21) Salvia leucophylla (20)
Non-natives (# bee species) Lavandula spp. and cultivars (56) Nepeta sp. and cultivars (53) Aster x frikartii (43) Vitex agnus-castus (39) Coreopsis sp. and cultivars (37) Penstemon sp. and cultivars (34) Erigeron karvinskianus (32) Cosmos bipinnatus (32) Perovskia atriplicifolia (30) Rosmarinus officinalis and cultivars (29)