Bees and Human Landscapes: The Turf Lawn. By: Ian Lane Department of Entomology, UMN

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1 Bees and Human Landscapes: The Turf Lawn By: Ian Lane Department of Entomology, UMN

2 Bee Diversity Represented by 9 families, with 6 occurring in North America Andrenidae, Halictidae, Apidae, Megachilidae, Colletidae, Melittidae >20,000 species worldwide, >3,600 occurring in the United States (DiscoverLife.org) Current published surveys put species estimates for 325 (Wolf and Ascher 2008) The UofMN Insect Collection contains >425 species collected in MN

3 Ways of Life Solitary >98% of Bee Species Tunnel Nesting 30% of Bee species Ground Nesting 70% of Bee species Social <2% of Bee Species Cavity Nesting Most Social Species

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5 Benefits of Bee Diversity Bee diversity on farms is enhancing yields for many pollinatordependent crops Almonds (Brittain et al. 2013) Sunflower (Greenleaf and Kremen 2006) Strawberry (Chagnon et al. 1993) Blueberry (Rogers et al. 2014) Coffee (Klein. 2003) (Garibaldi et al. 2014)

6 Wild Bee Species Decline Midwest - Carlinsville, IL (Burkle et al. 2013) >50% decline in bee species when compared to historic records (54/109 species rediscovered) Evidence of reduced pollination system resilience

7 Wild Bee Species Decline Midwest - Carlinsville, IL (Burkle et al. 2013) >50% decline in bee species when compared to historic records (54/109 species rediscovered) Evidence of reduced pollination system resilience

8 Wild Bee Species Decline Midwest - Isasca, MN (Gardner et al. 2014) 11 species not rediscovered from 1937 data 3 New Species Found

9 Rusty Patched Bumble Bee The rust patched bumble bee 87% population decline

10 Other MN Bumble Bee Declines Bombus terricola Bombus pennsylvanicus increasingly rare and were not detected in many parts of their range

11 What are the Causes? Forage plants and nutrition Richness, abundance, and quality of of plants affect bumble bee diversity and solitary bee diversity Declines in plants correlated with declines in bees Nesting site resources and location Cavity nester diversity adversely affected by disturbances and small patch sizes

12 Honey bees Colony nutrition affects response to other stresses. Nutrition supplements common

13 Species Reduction and Fragmentation Urbanization Agriculture These two human activities are the main drivers of habitat reduction and fragmentation, resulting in species losses of Plants and Bees.

14 Urbanization

15 Measuring Urbanization Urbanization is classified along a gradient Many Studies Use Percent Impervious Surface to determine intensity Pavement and buildings = impervious surfaces Usually use Low-Medium-High

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17 (McKinney, 2008) Urbanization and Wildlife Numbers of Vertebrate and Invertebrate species tend to decline with increasing urbanization worldwide Plant Species tend to increase from low to middle levels of urbanization Plant species decrease from mid to high levels of urbanization

18 Urbanization and Bees Bee species tend to decline with increasing urbanization More exotic bees in urban areas More floral generalist All this is highly variable

19 Case Study: New York, NY

20 Case Study: New York, NY Green spaces vs. neighborhoods Green Spaces had more vegetation cover, and higher bee diversity BUT, green space cover was more associated with trees and shrubs negatively impacted flowering plants

21 Case Study: New York, NY Green spaces vs. neighborhoods Neighborhoods had less vegetation cover BUT, Neighborhood vegetative cover was more associated with flowering plants Neighborhoods were more variable in Bee species composition Based on Development Intensity and Vegetation Management

22 Case Study: What Does It Mean Green spaces are superior because of the sheer area of vegetative cover Flowers were more attractive here Likely provided more nesting opportunities Neighborhoods have the potential to house more flowers than green spaces if managed properly

23 Impatiens Petunia Hydrangea Rose Violets Lilies Plants common in neighborhoods but not green spaces Removing them from their analysis increased the ability of flowers to predict bee visits in neighborhoods

24 Rethinking our Neighborhoods

25 Reconciliation Ecology Pollinator conservation has largely embraced the concept of reconciliation ecology (Rosenzweig 2003)

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27 Large proportions of urban areas are not impervious surface, but vegetative areas such as lawns and trees

28 The Turf Lawn 163,812 km 2 turf cover in U.S. 1.9% of continental U.S. Largest irrigated crop (Milesi et al. 2005) Used as a reliable and durable ground cover for human activity and aesthetics. Managed predominantly as a monoculture

29 Green Desert? Some lawn weeds can host a diversity of flower-visiting insects (Larson et al. 2014) 37 species of bees documented Reduced mowing in England increased the number of flowering plants and total flowers produced. This resulted in more flower visiting insects (Garbuzov et al. 2014)

30 The Lawn Question Would it be possible to add more floral diversity to lawns? Would adding diversity to lawns improve the health of urban bee communities (and beyond)?

31 Challenges Grasses are competitive and plants are under constant mowing stress People have strong biases on lawn aesthetics and flowering plants Weedy or Native Plants Target Owner Preference

32 Changing Ideals? Conflicting opinion on lawn weeds in Twin Cities Research has revealed a large range of views on many different lawn weeds (Dahmus & Nelson, 2013)

33 Research Program The UMN Bee lab and Turf lab are conducting collaborative research Focusing on five studies to investigate different aspects of lawn systems Strong focus on native plants

34 Study 1 Companion Grasses Goal To identify a grass species that would be most amenable to a flowering lawn seed mix Four grass species hard fescue, Kentucky bluegrass, tall fescue, and perennial ryegrass Seeded with Kura Clover

35 Initial Results

36 Study 2- Plants and Mowing Height Goals To identify a diversity of forbs that will persist in a seeded turf stand, and to evaluate how mowing management affects establishment and flowering. 2 mowing treatments 2.5 inches, 3.5 inches Mow timing determined by 1/3 rule

37 Plants Tested Anemone patens Pasque flower Claytonia virginica Spring Beauty Erigeron compositus Cutleaf daisy Thymus serpyllum Creeping Thyme Astragalus crassicarpus Ground Plumb Prunella vulgaris spp. Lanceolata Self-Heal Trifolium repens Dutch White Clover Oxytropis lambertii Purple locoweed

38 Bloom Time of Selected Plants March April May June July August Sept. Oct. Anemone patens x x x Astragalus crassicarpus x x Claytonia virginica x x x Oxytropis lambertii x x x Erigeron compositus x x Trifolium repens x x x x x x Prunella vulgaris spp. lanceolata x x x x x Thymus serpyllum x x x

39 Preliminary Results 4 Species were found in plots 2 bloomed in first year Mowing height did not significantly affect plant establishment or bloom Dormancy factors likely related to why we didn t see more germination

40 Leaves Site-Specific Differences in Forb Establishment 120 Thyme Leafing units 120 Self-heal Leafing Units Becker St. Paul 0 Becker St. Paul

41 Study 3 Native Plant Mow Tolerance Goal To identify native plants that may adapt and flower in the presence of mowing pressure. 5 species of native plant Three treatments control, 3-inch, and 8- inch cutting height. Mow timing determined by 1/3 rule

42 Calico aster Aster lateriflorus Lanceleaf coreopsis Coreopsis lanceolata Field mint Mentha arvensis Dotted beebalm Monarda punctata Canada milkvetch Astragalus canadensis March April May June July August Sept. Oct. Coreopsis lanceolata x x x x Astraglus canadaensis x x x Monarda punctata x x x Mentha Arvensis x x x Aster lateriflorus x x x

43 Study 4 Clover-visiting bee community Goal To form a baseline knowledge of how bee communities respond to existing lawn flowers Allows us to draw conclusions about how enriching lawns affects a large community of species

44 Bumble Bee Abundance Honey Bee Abundance Bees Respons to Clover Bloom Bumble Bee Visitation to Clover Honey Bee Visitation Clover Flowering Heads Flowering Heads 10 bee genera found on late blooming clover, showing a strong response to flower density

45 Study 5 Establishment Methods Goals Identify methods for establishing forbs in mature turf to aid in land manager adoption Strategies for over-seeding forbs into mature turf stands Three Species Four treatment plots control, aeration, scalping, aeration/scalping Three different seeding rates

46 Summary Study 1 Hard fescue and Kentucky bluegrass identified as promising grasses for future mixes. Seeding rate was non-significant over range tested Study 2 Four forb plants established in turf plots, with two flowering in first year. No differences in mowing height were found Study 3 Results from native plant mowing treatments will help inform future native plant selection

47 Summary, cont. Study 4 Monitoring bee species use and response to clover will help form a baseline for how adding floral richness will affect bee communities, initial sampling has provided useful insights. Study 5 Results of mature turf stand over seeding and disruption will help homeowners adopt flowering species

48 Big Picture Our research will form the basis of future flowering lawn recommendations and research That advocacy and outreach regarding flowering lawns will contribute to a shift in the way we design landscapes and conserve bee (and all) species.

49 Questions? Photo by: Joel Gardner