Enhancing Invertebrate Habitat on the Intensive Green Roof

University of Pennsylvania ScholarlyCommons

Internship Program Reports Education and Visitor Experience

3-2020

Nate Flicker

Follow this and additional works at: https://repository.upenn.edu/morrisarboretum_internreports

Recommended Citation Flicker, Nate, "Enhancing Invertebrate Habitat on the Intensive Green Roof" (2020). Internship Program Reports. 66. https://repository.upenn.edu/morrisarboretum_internreports/66

This paper is posted at ScholarlyCommons. https://repository.upenn.edu/morrisarboretum_internreports/66 For more information, please contact [email protected]. Enhancing Invertebrate Habitat on the Intensive Green Roof

This report is available at ScholarlyCommons: https://repository.upenn.edu/morrisarboretum_internreports/66 1

Title: Enhancing Invertebrate Habitat on the Intensive Green Roof

Author: Nathaniel Flicker The Hay Honey Farm Endowed Natural Lands Intern

Date: Wednesday March 25, 2020

Abstract:

Green roofs provide numerous ecological and anthropogenic benefits addressing issues of urban sustainability and environmental degradation. One of these benefits is the habitat value green roofs provide for a diverse array of insects. The intensive green roof at Bloomfield Farm of Morris Arboretum supports a diverse and abundant community of insects; however, past insect community surveys from 2017 reveal a deficiency of beetles (Order: Coleoptera), butterflies, moths, and caterpillars (Order: Lepidoptera), and bees (Order: Hymenoptera, Superfamily: Apoidea). This project aims to enhance the habitat quality for insects, specifically Coleopterans, Lepidopterans, and bees, by amending flower forage and nesting resources on the green roof. Insect habitat was amended in a designated area of the intensive green roof through the addition of a diverse collection of flowering plants and abiotic nesting resources, including deadwood, bark, sand-clay substrate, bee nesting tubes, and rocks. Through the installment of plant forage and construction of diverse microclimates, this project improves the overall insect habitat quality of the intensive green roof at Bloomfield Farm.

TABLE OF CONTENTS Abstract...... 1 Introduction...... 3 Materials and Methods...... 4 Results...... 10 Discussion...... 11 Management Plan...... 13 Conclusion...... 14 Acknowledgements...... 14 References...... 15 Appendix...... 18

LIST OF TABLES TABLE 1. Plants Purchased for Green Roof...... 6 TABLE 2. Plants Propagated for Green Roof...... 6

LIST OF IMAGES IMAGE 1. Rooftop Wet Area...... 7 IMAGE 2. Sand-Clay Mound...... 8 IMAGE 3. Habitat Logs...... 9 IMAGE 4. Bee Tubes in Habitat Logs...... 10 IMAGE 5. Deadwood and Bark...... 10

LIST OF APPENDICES APPENDIX A. Plant Selection Information...... 18 APPENDIX B. Bloom Map of Green Roof Planting...... 19 APPENDIX C. Recommendations for Future Plantings on the Intensive Green Roof. ...20 APPENDIX D. Butterfly Planting Recommendations for Bloomfield Farm...... 23

INTRODUCTION Urbanization and suburban sprawl have devastating effects on environmental systems and ecological services, leading to habitat loss, urban heat island effects, air and water pollution, and groundwater depletion (Snodgrass & Snodgrass 2006). ). In American cities, impervious surface cover can reach from 17.7% to a whopping 61.1% of urban land area (Nowak & Greenfield 2012). Not only is impervious surface cover increasing in American cities (+0.31% per year), but urban tree cover is decreasing at a comparable rate (-0.27% per year) (Nowak & Greenfield 2012). Impervious urban infrastructure prevents water infiltration, exacerbates runoff and localized flooding, increases water pollution, and overwhelms urban storm water systems, damaging the biodiversity, water quality, and sustainability of urban watersheds (Kim et al. 2016). Rooftops comprise roughly 15-35% of urban land area (Winkless 2018) and significantly contribute to urban impervious surface cover in the U.S. and corresponding effects of environmental degradation. While green roofs have been a popular alternative to conventional roofs for many decades in European cities, particularly in Germany, Switzerland, and the UK, the use of green roofs was not widespread in North America until the end of the 20th century with the emergence of the Leadership in Energy and Environmental Design (LEED) Initiative and other green building incentives (Snodgrass & Snodgrass 2006). Green roofs offer a wide range of ecological and anthropogenic benefits that enhance urban livability and sustainability. Because they serve no use beyond their structural functions, rooftops present a novel venue for mitigating urban environmental issues. Green roofs improve localized storm water management by retaining rainwater runoff and enhancing filtration of particulates and pollutants and thereby reducing localized flooding and improving water quality (Snodgrass & Snodgrass 2006; Gedge et al.). By providing semi-isolated habitats with atypical environmental conditions, green roofs also promote local biodiversity of plants, birds, and insects (Gedge et al.; Oberndorfer et al. 2007). They mitigate air pollution by sequestering carbon and other pollutants from the atmosphere, producing oxygen, and combating urban heat islands (Snodgrass & Snodgrass 2006; Gedge et al.). Furthermore, green roofs contribute to energy conservation by improving building insulation (Oberndorfer et al. 2007; Gedge et al.). They extend rooftop waterproofing membranes and reduce rooftop maintenance by the protection they provide from UV light, frost, drastic temperature fluctuations, and mechanical damage (Oberndorfer et al. 2007). Green roofs also offer aesthetic and psychological value to people who interact with them (Oberndorfer et al. 2007; Gedge et al.; Hartig et al. 1991). Extensive research demonstrates that worker productivity and performance is higher in green or environmentally-friendly buildings (Horticulture Innovation Australia Limited 2017; Miller et al. 2009; Heerwagen 2010). Additionally, green roofs offer opportunities for urban agriculture, local food production, and environmental education in urban environments that may otherwise be devoid of green space (Oberndorfer et al. 2007). As a result of their broad range of ecological and anthropogenic benefits, green roofs may play an important role in the University of Pennsylvania’s Climate and Sustainability Action Plan 3.0 for 2019-2024 (University of Pennsylvania 2019). In addition to the above benefits, green roofs can also provide habitat for insects and promote local insect diversity (Oberndorfer et al. 2007). Despite the thin substrate layer on green roofs and their relative isolation from ground-level habitats, significant research supports the value of green roofs to a wide array of arthropods, from beetles (Coleoptera, Carabidae, Curculionoidea) and spiders (Arachnida) (Gedge & Kadas 2005, Brenneisen 2003; Brenneisen 5

2006; Braaker et al. 2014) to bees (Hymenoptera) (Colla, Willis, & Packer 2009), springtails (Collembola), and centipedes (Chilopoda) (Schindler, Griffith, & Jones 2011), as well as true bugs (Hemiptera), butterflies and moths (Lepidoptera), lacewings (Neuroptera), and mantises (Mantodea) (Nestory 2018). In fact, a 2005 study found that as much as 10% of the insect species collected from green roofs in London were considered nationally rare, scarce and/or as having restricted ranges (Gedge & Kadas 2005). Green roofs have also been shown to support an abundance and diversity of spiders (Brenneisen 2003) and bees (Colla, Willis, & Packer 2009) comparable to ground-level sites and “offer suitable habitat for foraging and/or nesting for a variety of bee species,” demonstrating their relevance to insect habitat conservation. It is clear that green roofs have the capacity to mitigate the detrimental effects of habitat loss on various communities of insects and, because of the additional ecological benefits they confer, present an attractive solution to addressing urban ecological issues more broadly. However the unique role green roofs may play in the ecological planning of biodiverse landscapes has been underestimated (Brenneisen 2006). Green roofs present harsh environmental conditions to the organisms that inhabit them. Compared to ground-level sites, green roofs have greater susceptibility to severe drought, extreme temperatures, intense and persistent light, and heavy winds (Oberndorfer et al. 2007). Consequently, the plants that thrive on green roofs are most often low-growing, compact, shallow-rooted, resilient, and adaptable, tolerating low-nutrient soils and withstanding extensive periods of extreme heat and drought (Oberndorfer et al. 2007; Snodgrass & Snodgrass 2006). The establishment of native, localized plant communities on green roofs can be a challenge because of the ecological discrepancy between green roof and ground-level conditions (Oberndorfer et al. 2007). Despite the harsh environmental conditions of green roofs, the intensive green roof at Bloomfield Farm supports a diverse and abundant community of insects. In 2017 and 2018, Samantha Nestory, former Hay Honey Farm Endowed Natural Lands Intern, conducted an insect survey of the intensive green roof at Morris Arboretum. Using an insect vacuum, Nestory collected a total of 891 insects of the orders Lepidoptera, Coleoptera, Hemiptera, Hymenoptera, Neuroptera, and Mantodea. She identified a deficiency of insects in the orders of Coleoptera and Lepidoptera as well as a low diversity of bee species (Nestory 2018). This project aims to use biotic and abiotic habitat amendments to enhance the habitat quality of the green roof for insects, specifically targeting Coleopterans, Lepidopterans, and bees. MATERIALS AND METHODS The intensive green roof at Morris Arboretum was constructed in 2009 atop a 6-bay, non- insulated garage and was first planted in 2010. The green roof, which is approximately 3,750 square feet, has a pitch of 2.5 inches or 9.46 degrees and faces southeast (Nestory 2018). The roof supports approximately 6 inches of rocky, alkaline substrate with low organic matter and nutrient content. The intensive green roof has a diverse array of native and non-native species, including grasses, woody shrubs, and herbaceous perennials. A total of 158 taxa have been grown on the green roof and, as of August 2017, 141 taxa persisted on the roof, including 58 species native to the United States and 24 species native to Pennsylvania (Nestory 2018). The area designated for insect habitat remediation is approximately 351 square feet of the roof located on the southwestern side of the structure. 6

Extensive research was compiled to determine which plants and abiotic environmental components would enhance insect habitat in a green roof setting. Research consisted of a review of the available literature regarding insect biodiversity on green roofs as well as various site visits to horticulturists in the Philadelphia area. The gravel and rock gardeners at Chanticleer, a Pleasure Garden and Mt. Cuba Center were consulted for plants they would recommend for a pollinator-friendly planting in green roof conditions. I also visited nurseryman, author, and acclaimed green roof expert Ed Snodgrass of Emory Knoll Farms to speak about potential plants and structural additions to enhance insects on the green roof. The addition of a diverse collection of flowering perennials contributes foraging and nesting organic matter for the green roof insect community. The project plot already contains several established plants that will be incorporated into the new planting, including: Phlox spp., Achillea spp., Monarda spp., Sedum spp., Geum triflorum, and Juniperus horizontalis. Plants were chosen for the new planting based on suggestions from the literature (Snodgrass & Snodgrass 2006; Hawke 2015), advice from horticulturists, plant cultural requirements, and their relative contribution to Hymenopteran and Lepidopteran pollinators. The following plants will be planted in April in the project area of the green roof:

Table 1. Plants Purchased for Green Roof. A total of 90 plants were purchased for the springtime planting on the intensive green roof from High Country Gardens in Albuquerque, NM.

Scientific Name Common Name Pot Size Quantity Delosperma nubigenum Hardy Yellow Ice Plant 2.5” 8 Ratibida columnifera Mexican Hat 2.5” 15 Asclepias tuberosa Butterfly Weed 2.5” 10 Eriogonum umbellatum Kannah Creek Sulphur Buckwheat 5” deep 15 “Kannah Creek” Symphyotrichum ericoides First Snow Heath Aster 5” deep 15 “First Snow” Symphyotrichum oblongifolium Raydon’s Favorite Aromatic Aster 5” deep 15 “Raydon’s Favorite” Liatris aspera Rough Blazing Star 2.5” 12

In addition to the potted plants sourced from High Country Gardens, six taxa were propagated from seed in the greenhouse facilities at Morris Arboretum. The following plants were propagated from seed for use on the green roof:

Table 2. Plants Propagated for Green Roof. Plants propagated for the springtime planting on the intensive green roof.

Scientific Name Common Name Cerastium arvense Field Chickweed Bigelowia nuttallii Nuttall’s Rayless Goldenrod Penstemon tubaeflorus White Wand Beardtongue Penstemon canescens Eastern Gray Beardtongue Penstemon davidsonii v. menziesii Menzies’ Beardtongue Penstemon pinifolius Pineleaf Beardtongue

In addition to the installment of perennial flowers attractive to pollinators, various insect habitats were replicated on the intensive green roof to create potential nesting sites for a diverse community of insects. Rooftop microhabitats were constructed using rocks, a coarse sand-clay mix, dead wood, bark, hollow plant stems, and pond liner in order to encourage a diverse collection of insects on the roof (Brenneisen 2006). The following habitat features were added to the intensive green roof for this project: • A small wet area of approximately 6 square feet was constructed using a piece of impermeable pond liner and rocks gathered from materials handling at Bloomfield Farm. Rocks were used to replicate a scree slope at the base of the wet area.

Image 1. Rooftop Wet Area. The small wet area on the roof was constructed using pond liner, green roof substrate, and rocks collected from the Morris Arboretum’s materials handling area. At its highest capacity this area can hold up to 9.5 gallons of water. Photographed by Louise Clarke, 2020.

• Three hundred pounds of traction grit, a coarse sand-gravel substrate, and 50 pounds of Turface® MVP®, a high-porosity calcined clay product, were mixed and mounded against logs and pieces of deadwood in the project area. Wood was partially buried around the perimeter of the sandy area to contain the substrate and maintain an adequate depth for ground-nesting bees.

Image 2. Sand-Clay Mound. Three hundred pounds of coarse sand substrate, traction grit, were mixed with 50 pounds of calcined clay, Turface® MVP®, to create a mound of substrate for ground-nesting bees. The sand-clay mix was confined by and mounded on deadwood to prevent it from dissipating over time. Photograph on the left taken by Eloise Gayer.

• Hollow logs containing bee nesting tubes were also added to the project area. Two Paulownia (Paulownia tomentosa) logs and one gray birch (Betula populifolia) log were installed on the roof. While the logs were naturally hollow, a chainsaw was used to widen the log cavities in order to accommodate bee tubes within them. The gray birch log was also drilled with a ¼ in. and 5/16 in. bit to provide additional nesting cavities for bees. Logs were partially buried in substrate and rocks to secure their south-facing position on the roof. 9

Image 3. Habitat Logs. Paulownia tomentosa logs are in the foreground and the larger gray birch log is in the background. Log cavities were filled with bundles of nesting tubes of bees. Photographed by Louise Clarke, 2020.

• Nesting tubes were cut from Phragmites australis (Phragmites) and Phyllostachys aurea (bamboo) with a scroll saw to approximately 6 inches in length (MacIvor 2017). Tubes ranged in diameter from 1-2 mm. to approximately 25 mm. in order to encourage a diversity of bee species with a range of body sizes (MacIvor 2017). Phragmites nesting tubes were fastened into a bundle with rubber bands and copper wire before being placed in the log cavities. Bamboo tubes were used to fill the remaining cavity surrounding the Phragmites bundles. Bark and rocks were used to further secure and protect nesting tubes in the logs. 10

Image 4. Bee Tubes in Habitat Logs. Bee nesting tubes, which were cut from Phyllostachys aurea and Phragmites australis, were bundled and set into the hollow cavities of the habitat logs, offering them protection from wind and precipitation. Photographed by Louise Clarke, 2020.

• Deadwood and bark was placed behind the Paulownia habitat logs to offer additional habitat for insects.

Image 5. Deadwood and Bark. A piece of deadwood from the large Fagus grandifolia (American Beech) in the Morris Arboretum Sheep Meadow was piled with pieces of bark from a diversity of trees to create novel nesting habitat for a diverse collection of insects.

In addition to these amendments, we maintained bare spots and added Wissahickon Schist rocks to encourage colonization by ground-nesting insects (Brenneisen 2003; Gedge et al.).

RESULTS The management of diverse microhabitats is essential to sustaining a diverse community of insects. Specifically, structural diversity in substrate depth and type are important factors in influencing insect diversity on green roofs (Gedge & Kadas 2005; Brenneisen 2003; MacIvor & Ksiazek-Mikenas 2015). Varying substrate depth, size, drainage regimes, and biomass levels “provides a mosaic of microhabitats at roof level, thereby increasing…biodiversity of…both flora and fauna” on the roof (Gedge & Kadas 2005). Additionally, the use of rotting wood, rocks, dead plant matter, wet areas, bee tubes, sand mounds, and overwintering locations can further maximize rooftop biodiversity (Gedge et al.). Approximately 5,000 species of bees inhabit North America, the vast majority of which are solitary and nest in soil burrows. About 10% of these species nest in above-ground cavities including hollow stems or reeds, holes created by wood-boring animals, and rock crevices; some dig their own burrows in wood (Bohart 1971; Graham et al. 2014) and ground-nesting bees burrow in sand-based substrates (Cane 1991; Gedge et al.). Solitary bees, as central place foragers, will forage in a relatively small range surrounding their nesting sites (MacIvor 2016) in order to provision their eggs with pollen and nectar resources for emerging juveniles (Graham et al. 2014). Consequently, it is important to position solitary bee nesting habitat in close proximity to flower forage. Only about 100 species of North American bees are social, nesting in large colonies (Bohart 1971). The addition of new wildflowers, bee nesting tubes, habitat logs, patches of bare substrate, and a sandy bee bank on the green roof will encourage colonization by a diverse community of bee pollinators (Gedge et al.; Brenneisen 2006; Gedge & Kadas 2005). Beetles (Order: Coleoptera) represent the largest order of insects and constitute a fifth of all living organisms on the planet (Natural History Collections of the University of Edinburgh). Their amazing species richness is reflected in the diverse range of life cycles and ecological functions that they occupy (Natural History Collections of the University of Edinburgh). Beetles have exploited all habitats and possible food resources, ranging from herbivores and scavengers to predators and parasites. They are found in all habitats, occurring on vegetation, under bark, rocks, or leaf litter, on or beneath the soil surface, as well as in fungi, rotting wood and vegetation, dung, and decaying organisms (Borror & White 1970). The addition of native plants, dead wood, rocks, wet areas, bark, and substrate diversity are expected to benefit beetle diversity and abundance on the green roof. Butterflies, which are diurnal, and moths, their nocturnal counterparts, represent the second largest order of insects, Lepidoptera (Meyer, 2016). Many Lepidoptera species are valued for their morphological elegance and beauty in both their adult and larval stages (Meyer 2016). Lepidopteran larvae, caterpillars, feed on vegetation while adult moths and butterflies generally feed on floral nectar. Warm microclimates, including bare and rocky locations, are vital to the development of some caterpillars (Butterfly Conservation). Similarly, butterflies require sunny, south-facing slopes where they can safely bask before taking flight (Butterfly Conservation). Moths and butterflies also require overwintering sites—typically taller vegetation and brambles left uncut through the winter season. Variable habitat structure and landscape-level habitat management is important to sustaining diverse and healthy Lepidopteran communities (Butterfly Conservation). A variety of wildflowers attractive to butterflies and moths were planted on the roof. Additionally, bare spots and rocky, south-facing areas were provisioned to allow butterflies to comfortably bask on the green roof. 12

DISCUSSION Green roofs, as semi-isolated habitats with novel environmental conditions, have the capacity to promote insect biodiversity through the use of specific plants and structural design features (Gedge & Kadas 2005; Brenneisen 2006; Brenneisen 2003). The intensive green roof at Bloomfield Farm supports a diverse community of insects; however, it is deficient in insects in the orders of Coleoptera and Lepidoptera and it fails to support a diverse and abundant community of bee pollinators (Nestory 2018). Over the course of this project, nesting and foraging resources were installed on the intensive green roof to enhance the habitat quality for insects, specifically those in the orders of Coleoptera, Lepidoptera, and Hymenoptera. The biotic amendments used for this project consisted of a diverse group of 13 taxa of flowering perennials. Seven of these species were ordered as potted plants while six additional taxa were propagated from seed. Plants were chosen for the planting based on their contribution to pollinator foraging and their potential associations with native insect fauna. The abiotic components of this project involved the addition of deadwood, bark, sand and clay, rocks, and hollow nesting tubes. These abiotic habitat features were used to create diverse microclimates, varying substrate type, substrate depth, drainage regimes, and structural features, to accommodate a diverse community of insects on the green roof (Gedge and Kadas 2005; Brenneisen 2006). The installment of overwintering sites and floral forage resources is expected to benefit the entire insect community on the roof, including beneficial predatory and parasitoid insects (Hassan et al. 2016; Landis, Wratten, & Gurr 2000; Lady Bird Johnson). Because the current insect community data for the intensive green roof was compiled in August of 2017, it would not be feasible to evaluate the efficacy of the habitat amendments before the end of the internship period in June. This represents both a limitation of the project as well as an opportunity for a future intern project. However, the relative contributions of specific habitat amendments and plant species to colonizing insects may be approximated through future monitoring and formal evaluations. Some habitat amendments target specific genera or insect groups that should be sought out in future insect community evaluations.

• Bee nesting tubes may be attractive to a number of species of solitary bees including: cellophane bees (Hylaeus spp.), mason bees (Osmia spp.), and leafcutter and resin bees (Megachile spp.) (Gareau at al. 2017). • Mounded, sand-based substrate has the potential to attract ground-nesting bees and wasps including sweat bees (Halictus spp.), bumblebees (Bombus spp.), squash bees (Peponapis pruinosa), and mining bees (Andrena spp.) (Gareau et al. 2017) as well as digger wasps (Sphex spp.) and the paraphyletic sand wasps (Crabonidae), among others (Texas A&M University 2020). • Deadwood will attract primarily beetles, like the flower longhorn beetle (Strangalia famelica), as well as carpenter bees (Xylocopa spp.), solitary bees, and cavity-nesting wasps (Gedge et al.). • Rocks offer refuge to a wide diversity of insects in the orders of Coleoptera, Lepidoptera, and Hymenoptera. Many insects nest beneath rocks because they warm up faster from sunlight than loose substrate, creating warm microclimates 13

throughout the year (Gedge et al.). They may also be used by bees, butterflies, and other insects as perches to bask in the sun. • The wet area may be used by all types of insects as a drinking spot throughout the year. It will also provide a cooler microclimate when retaining water.

Various wildflowers chosen for this project also demonstrate specific faunal associations with insects to be considered in future evaluations.

• Asters, including Symphyotricum oblongifolium ‘Raydon’s Favorite’ and Symphyotrichum ericoides ‘First Snow’ attract larger predatory insects like lady beetles and soldier beetles (PennState Extension 2015) while providing special significance to native bees as a result of their uniquely late bloom period (Lady Bird Johnson Wildflower Center). Both species are host plants for the caterpillars of the Silvery Checkerspot butterfly (Chlosyne nycteis) as well as a diverse array of moths including, but not limited to, the Isabella Tiger Moth (Pyrrharctia isabella), the Common Pug (Eupitheica miserulata), the Saddleback Caterpillar (Acharia stimulea), the Brown-Hooded Owlet (Cucullia convexipennis), and the Aster-Head Phaneta (Phaneta tomonana) (Hilty 2017). Similarly, both species support predatory and parasitoid insects (Lady Bird Johnson Wildflower Center). o Symphyotrichum oblongifolium is one of the last wildflowers to bloom in the fall before frost (Hilty 2017). It attracts long- and short-tongued bees, butterflies, and skippers (Hilty 2017). o Symphyotrichum ericoides attracts a wide diversity of insects, including long- and short-tongued bees, beetles, moths, butterflies, skippers, plant bugs, flies, and wasps (Hilty 2017). In addition to the Silvery Checkerspot (Chlosyne nycteis), Symphyotrichum ericoides is a larval host for the Pearl Crescent butterfly (Phyciodes tharos), whose caterpillars feed on the flowers and foliage (Hilty 2017). • Asclepias tuberosa attracts a diverse array of native bees, wasps, butterflies, moths, and beetles. The caterpillars of Monarchs (Danaus plexippus) and Unexpected Cycnia moths (Cycnia inopinatus) prefer this plant as a larval food source (Hilty 2017). Asclepias tuberosa is also attractive to the large milkweed bug (Oncopeltus fasciatus), the small milkweed bug (Lygaeus kalmii), the blackened milkweed beetle (Tetraopes melanurus), and the Curve-Tailed Bush Katydid (Scudderia curvicauda) (Hilty 2017). It has special value to native bees, bumblebees, and honeybees and is attractive to predatory and parasitoid insects (Lady Bird Johnson Wildflower Center). • Ratibida columnifera attracts short-tongued bees, beetles, wasps, and flies. It may also attract butterflies and skippers (Hilty 2017). Various moths feed on Ratibida spp. including the Sunflower Moth (Homoeosoma electellum), the Blackberry Looper Moth (Chlorochlamys chloroleuca), and the Wavy-Lined Emerald (Synchlora aerata) (Hilty 2017). Ratibida columnifera has special value to native bees (Lady Bird Johnson Wildflower Center). • Liatris aspera attracts long-tongued bees as well as the butterflies of Monarchs (Danaus plexippus), Painted Ladies (Vanessa cardui), and Black Swallowtails (Papilio polyxenes), among others. It is a larval food source for the Glorious Flower Moth (Schinia trifascia) 14

(Hilty 2017) and has special significance for native bees and bumblebees (Bombus spp.) (Lady Bird Johnson Wildflower Center). • Eriogonum umbellatum has special value to native bees and is attractive to predatory or parasitoid insects (Lady Bird Johnson Wildflower Center). It is also a larval host plant for the Lupine Blue moth (Plebejus lupini) (Lady Bird Johnson Wildflower Center).

While this in no way exhausts the list of insects I hope to attract on the green roof, it does demonstrate some of the specific insects that may appear in subsequent years as a result of the added wildflowers and habitat amendments. By providing sources of pollen and nectar, living plants, and abiotic nesting resources, my project area offers insects food and sheltered microclimates for nesting and overwintering. Future research endeavors may assess the efficacy of this project and potentially expand the habitat amendments across the remaining roof area.

MANAGEMENT PLAN

The project area should be revisited routinely for maintenance reasons. Depending on weather conditions, the plot should be hand-weeded once every 2-4 weeks. Weeding is particularly important in the first two years to minimize competition for the new planting as it establishes on the roof. Plants should be watered on dry or particularly hot weeks throughout the spring, summer, and fall. Watering will also be particularly important in the first year to help the new planting establish. Depending on the conditions, water may also be added to the impermeable wet area; however, this area will naturally collect rainwater and act as an ephemeral pool. The wet area should be monitored for leaking and runoff scouring through the constructed berm, with repairs taking place as needed.

Certain plants, including Asclepias tuberosa, Symphyotrichum oblongifolium “Raydon’s Favorite,” Symphyotrichum ericoides “First Snow,” and Liatris aspera may need to be replaced over time due to insect herbivory because they provide food for native beetles and caterpillars. Signs of insect herbivory would reflect the success of the new planting in attracting insects to the green roof. Abiotic resources, including logs, bee tubes, and deadwood, may also need to be replaced over time, depending on their level of deterioration on the roof. Consequently, it will be important to monitor plants and habitat amendments on the roof for signs of deterioration that may impede future insect colonization.

Future native ground-level plantings on Bloomfield Farm may also enhance insect colonization of the intensive green roof by providing nearby nectar sources for butterflies and moths as well as host plants for caterpillars. Appendix A contains a list of native perennials, grasses, shrubs, and trees with specific Lepidopteran associations which should be considered in future plantings around the intensive green roof (Ruffin 1996; NABA—North Jersey Butterfly Club). While a formal evaluation cannot be accommodated by the project timeline, casual and complex observation can be used to identify the insects attracted to the project area. Timed sweep-netting on flowers and pan traps can be used to gauge the success of the habitat amendments (MacIvor & Ksiazek-Mikenas 2015). Photographs and simple observation may also be a viable means of collecting casual, though informative, data. Collected insects should be identified to the finest taxonomic order using dichotomous keys and/or partnering with local 15 invertebrate experts at universities around the Arboretum (MacIvor & Ksiazek-Mikenas 2015). Any future formal insect community evaluation should follow the methods used in Nestory, 2018 for a direct comparison of sampled insect fauna (Nestory 2018). Future monitoring efforts will demonstrate the strengths and limitations of the habitat amendments used for this project to inform further design and management on the intensive green roof (MacIvor & Ksiazek-Mikenas 2015). CONCLUSION The intensive green roof at Bloomfield Farm is already home to a diverse community of insects; however, the past insect community survey demonstrates a deficiency of insects in the orders of Coleoptera and Lepidoptera as well as a low abundance and diversity of bee species. This project aimed to enhance insect abundance and diversity on the green roof through the provisioning of floral and nesting resources. Nesting and overwintering sites, in the form of deadwood, bark, hollow plant stems, sand-clay substrate, rocks, and water, were added to the green roof to promote insect colonization while a diverse wildflower planting was installed to enhance floral resources for insects. Although habitat amendments were targeted towards Coleopterans, Lepidopterans, and bees, they will ideally provide resources to the broader community of insects on the roof in the years ahead. ACKNOWLEDGEMENT I would like to thank Louise Clarke, the Bloomfield Farm horticulturist at Morris Arboretum, for her constant support, contribution, and enthusiasm for this project. I also offer enormous gratitude to Keith Snyder, the Mechanic at Morris Arboretum, for lending his assistance, advice, materials, and equipment for the procuring and cutting of native bee tubes and habitat logs and to Mike Slater, who offered helpful advice regarding the creation of habitat for ground-nesting bees. I would also like to thank Ed Snodgrass of Emory Knoll Farms, Lisa Roper of Chanticleer, a Pleasure Garden, Vic Piatt and Susan Boss of Mt. Cuba Center, and Scott Fisher of North Creek Nurseries for giving me tours of their gardens and recommending specific plants for my project. Finally, I thank Andrew Hawkes for offering hollow logs and bark for the habitat amendments on the roof and for his assistance in hauling the gray birch log onto the roof.

REFERENCES Bohart, G. E. 1971. Management of Habitats for Wild Bees. All PIRU Publications. Paper 791. 252-266. https://digitalcommons.usu.edu/piru_pubs/791 Borror, D. J. & White, R. E. (1970). A Field Guide to Insects: America North of Mexico. Volume 19 of Peterson Field Guide Series. Houghton Mifflin Harcourt. Braaker, S., Ghazoul, J., Obrist, M. K., Moretti, M. 2014. Habitat Connectivity Shapes Urban Arthropod Communities: The Key Role of Green Roofs. Ecology. 95(4): 1010-1021. Brenneisen, S. 2003. The Benefits of Biodiversity from Green Roofs – Key Design Consequences. 1st North American Green Roof Conference: Greening Rooftops for Sustainable Communities. 323-329. Brenneisen, S. 2006. Space for Urban Wildlife: Designing Green Roofs as Habitats in Switzerland. Urban Habitats 4(1): 27-33. http://urbanhabitats.org/v04n01/wildlife_pdf.pdf Butterfly Conservation. Enhancing Habitats for Butterflies and Moths, https://butterfly- conservation.org/in-your-area/scottish-office/enhancing-habitats-for-butterflies-and- moths. Cane, J. H. (1991). Soils of Ground-Nesting Bees (Hymenoptera: Apoidea): Texture, Moisture, Cell Depth and Climate. Journal of the Kansas Entomological Society. 64(4): 406-413. Colla, S. R., Willis, E., & Packer, L. 2009. Can Green Roofs Proide Habitat for Urban Bees (Hymenoptera: Apidae)? Cities and the Environment 2(1): Article 4. DOI: 10.15365/cate.2142009 Discover Life. (2020). Retrieved from http://www.discoverlife.org/ Elvidge, C. D., Milesi, C., Dietz, J. B., Tuttle, B. T., Sutton, P. C., Nemani, R., Vogelmann, J. E. 2011. U.S. Constructed Area Approaches the Size of Ohio. Earth and Space Science News. 85(24): 233-236. https://doi.org/10.1029/2004EO240001 Gareau, T. P., DeBarros, N., Barbercheck, M., & Mortensen, D. (2017). Conserving Wild Bees in Pennsylvania. PennState Extension. Retrieved from https://extension.psu.edu/conserving-wild-bees-in-pennsylvania Gedge, D. & Kadas, G. 2005. Green Roofs for Biodiversity – Designing Green Roofs to Meet Targets of BAP (Biodiversity Action Plan) Species. World Green Roof Congress Conference Transcript. 177-184. Gedge, D., Grant, G., Kadas, G., Dinham, C. (n.d.). Creating Green Roofs for Invertebrates: A Best Practice Guide. Buglife. https://cdn.buglife.org.uk/2019/07/Creating-Green-Roofs- for-Invertebrates_Best-practice-guidance.pdf Gibb, T. J. Youth and Entomology. Purdue University, College of Agriculture, Department of Entomology. (2014). Importance of Insects, https://extension.entm.purdue.edu/radicalbugs/index.php?page=importance_of_insects. 17

Graham, J. R., Tan, Q., Jones, L. C., Ellis, J. D. (2014). Native Buzz: Citizen Scientists Creating Nesting Habitat for Solitary Bees and Wasps. Florida Scientist. 77(4): 204-218. Gregory, S. & Wright, I. (2005). Creation of Patches of Bare Ground to Enhance the Habitat of Ground-Nesting Bees and Wasps at Shotover Hill, Oxfordshire, England. Conservation Evidence. 2: 139-141. Hassan, K., Pervin, M., Mondal, F., Mala, M. (2016). Habitat Management: A Key Option to Enhance Natural Enemies of Crop Pest. Universal Journal of Plant Science. 4(4): 50-57. DOI: 10.13189/ujps.2016.040402. Hawke, R. 2015. An Evaluation Study of Plants for Use on Green Roofs. Plant Evaluation Notes, Chicago Botanic Garden. (38): 1-22. Heerwagen, J. (2010). Green Buildings, Organizational Success and Occupant Productivity. Building Research & Information. 28(5-6): 353-367. https://doi.org/10.1080/096132100418500 Hilty, J. (2017). Illinois Wildflowers, http://illinoiswildflowers.info/ Horticulture Innovation Australia Limited. (2017). Green Roofs Improve Worker Productivity. Nursery Papers. 1-4. https://www.greenlifeindustry.com.au/Attachment?Action=Download&Attachment_id=1 984. Insect, Bugs and Spider Identification - North America. (2020). Retrieved from https://www.insectidentification.org/ Kim, H., Jeong, H., Jeon, J., Bae, S. (2016). The Impact of Impervious Surface on Water Quality and Its Threshold in Korea. Water. 8(4): 111. https://doi.org/10.3390/w8040111 Lady Bird Johnson Wildflower Center. University of Texas at Austin. https://www.wildflower.org/ Landis, D. A., Wratten, S. D., Gurr, G. M. (2000). Habitat Management to Conserve Natural Enemies of Arthropod Pests in Agriculture. Annual Review of Entomology. 45(1): 175- 201. https://doi.org/10.1146/annurev.ento.45.1.175 MacIvor, J. S. & Ksiazek-Mikenas, K. 2015. Invertebrates on Green Roofs in R. K. Sutton (Ed.), Green Roof Ecosystems (pp. 333-355). DOI: 10.1007/978-3-319-14983-7_14 MacIvor, J. S. (2016). Cavity-Nest Boxes for Solitary Bees: A Century of Design and Research. Apidologie. 48: 311-327. https://doi.org/10.1007/s13592-016-0477-z Meyer, J. NC State University General Entomology. (2016). Lepidoptera: Butterflies/Moths, https://projects.ncsu.edu/cals/course/ent425/library/compendium/lepidoptera.html#histor y. Miller, N., Pogue, D., Gough, Q., Davis, S. (2009). Green Buildings and Productivity. Journal of Sustainable Real Estate. 1(1): 65-89. https://doi.org/10.5555/jsre.1.1.6402637n11778213. NABA—North Jersey Butterfly Club. (n.d.). Butterfly Caterpillar Plants for New Jersey Gardens. Retrieved from 18

https://www.naba.org/chapters/nabanj/Butterfly_Caterpillar_Host_Plants_for_New_Jersey_Garde ns.pdf Nestory, S. 2018. An Insect Community Study of the Morris Arboretum Green Roof. Internship Program Reports. 3. https://repository.upenn.edu/morrisarboretum_internreports/3 Nowak, D. J. & Greenfield, E. J. 2012. Tree and Impervious Cover in the United States. Landscape and Urban Planning. 107(2012): 21-30. https://doi.org/10.1016/j.landurbplan.2012.04.005 Oberndorfer, E., Lundholm, J., Bass, B., Coffman, R. R., Doshi, H., Dunnett, N., Gaffin, S., Köhler, M., Liu, K. K. Y., & Rowe, B. 2007. Green Roofs as Urban Ecosystems: Ecological Structures, Functions, and Services. Bioscience 57(10): 823-833. PennState Extension. (2015). Attracting Beneficial Insects, https://extension.psu.edu/attracting- beneficial-insects. Ruffin, J. (1996). North American Butterfly Association: Southeastern Pennsylvania. Retrieved from http://nababutterfly.com/wordpress/wp-content/uploads/2014/03/pa_southeastern.pdf Schindler, B. Y., Griffith, A., Jones, K. N. 2011. Factors Influencing Arthropod Diversity on Green Roofs. Cities and the Environment 4(1): Article 5. Smithsonian. BugInfo: Beetles. Information Sheet Number 177, https://www.si.edu/spotlight/buginfo/beetle. Snodgrass, E. C. & Snodgrass, L. L. (2006) Green Roof Plants: A Resource and Planting Guide. Timber Press, Inc. Portland, OR. Texas A&M University. (2020). Landscape IPM: Ground-Nesting Wasps and Bees. (2020). Retrieved from https://landscapeipm.tamu.edu/ipm-for-turfgrass/pests-turfgrass/digger- wasp/ The Natural History Collections of the University of Edinburgh. The Importance of Beetles, http://www.nhc.ed.ac.uk/index.php?page=25.123. University of Pennsylvania. (2019). University of Pennsylvania Climate and Sustainability Action Plan 3.0: 2019-2024. Retrieved from https://www.sustainability.upenn.edu/sites/default/files/downloads/CSAP_3_Final 10 31 2019_0.pdf Winkless, L. 2018. The Rise of the Urban Rooftop. Forbes. Accessed from https://www.forbes.com/sites/lauriewinkless/2018/08/10/the-rise-of-the-urban- rooftop/#1b93e986273d.

APPENDICES

Appendix A. Plant Selection Information. The table below contains relevant information regarding the plants selected for the new planting on the intensive green roof. It specifies the scientific name, the common name, the native range, the size, and the bloom time. The first seven plants listed were purchased in pots from High Country Gardens. The final six plants were grown from seed in the Morris Arboretum greenhouse facilities.

Scientific Name Common Name Native Range Height x Bloom Time Spread Potted Plants from High Country Gardens Delosperma nubigenum Yellow Ice Plant Southern Africa 3" x 8" Early Summer - Late Spring Ratibida columnifera Mexican Hat NA 12" x 8" June - September Asclepias tuberosa Butterfly Weed Eastern and 24" x 18" June - August Southern U.S. Eriogonum umbellatum Sulphur Flower Colorado 1' x 2' May-July var.aureum 'Kannah Creek' Buckwheat Symphyotrichum ericoides White Heath Central and 1' - 3' x 1' August - 'First Snow' Aster Eastern NA - 1.5' October Symphyotrichum Aromatic Aster Northeastern and 1'-3' x 1'- August - oblongifolium 'Raydon's Central U.S. 3' September Favorite' Liatris aspera Rough Blazing Eastern NA 2' - 3' x 1' August - Star - 1.5' October Propagation from Seed Cerastium arvense Starry Cerastium Temperate 4"-12" x April - August Northern 1'-3' Hemisphere Penstemon tubaeflorus White Wand Missouri 1' x 1'-3' May - June Beardtongue Penstemon canescens Appalachian Appalachians; 1' - 3' tall May - July Beardtongue PA to NC and AL Penstemon davidsonii var. Menzies' Western NA 8 - 10 cm. May - July menziesii Beardtongue Penstemon pinifolius Pineleaf Western U.S. 8" - 10" x May - July Penstemon 12" - 15" Bigelowia nutalli Nutall's Rayless Southern U.S. 10"-15" x Mid/Late Goldenrod 1'-3' Summer - Autumn

Appendix B. Bloom Map of Green Roof Planting. The table below shows when each of the plants chosen for the new planting on the green roof will bloom. The length of the bars represents the bloom time of each flower while the color of the bars represents the color of the bloom of each flower.

Scientific Name April May June July August September October Plants from High Country Gardens Delosperma nubigenum Ratibida columnifera Asclepias tuberosa Eriogonum umbellatum var. aureum 'Kannah Creek' Symphyotrichum ericoides 'First Snow' Symphyotrichum oblongifolium 'Raydon's Favorite' Liatris aspera Propagation Cerastium arvense Penstemon tubaeflorus Penstemon canescens Penstemon davidsonii var. menziesii Penstemon pinifolius Bigelowia nutalli

Appendix C. Recommendations for Future Plantings on the Intensive Green Roof. The following table contains a list of plant recommendations for future planting investigation on the intensive green roof at Bloomfield Farm. Many, though not all, of the plants in this table have not yet been tried on the intensive green roof. Plants were added to this list based off of recommendations from gravel and rock gardeners at Chanticleer, A Pleasure Garden in Wayne, PA and Mt. Cuba Center in Hockessin, DE as well as from Ed Snodgrass of Emory Knoll Farms.

Scientific Name Common Name Native Range Emory Knoll Farm Delosperma cooperi Ice Plant Southern Africa Ipomopsis rubra Standing Cypress Southeastern U.S. Liatris microcephala Smallhead Blazing Southeastern U.S. Star Liatris Spicata Blazing Star Eastern NA Monarda fistulosa Wild Bergamot NA Orostachys boehmeri Duncecap Asia Seseli gummiferum Moon Carrot Krym, Turkey Talinum calycinum/Phemeranthus Fameflower Central-Southern U.S. calycinus Teucrium chamaedrys Wall Germander Europe, W. Asia, N. Africa Thymus serphyllum Creeping Thyme Europe, W. Asia, N. Africa Eriogonum allenii Shale Barren VA and WV Buckwheat

Gravel Garden at Chanticleer, A Pleasure Garden Argemone platycerus Prickly Poppy Western U.S. Digitalis obscura Willow-Leaved Spain Foxglove Echinacea tennesseensis Tennessee Coneflower Tennessee Eschscholzia californica California Poppy Western U.S. Euphorbia myrsinites Myrtle Spurge S Europe, Asia Minor Glaucium flavum Yellow-Horned Poppy Europe, Africa, Asia Helianthemum 'Ben Fhada' Rock Rose Liatris elegans Pink-Scale Blazing SE U.S. Star Oenothera (Gaura) lindheimeri White Gaura SE U.S. Parthenium integrifolium Wild Quinine Eastern U.S. Perovskia atriplicifolia 'Blue Blue Spire Russian W Asia, E Europe Spire' Sage Perovskia atriplicifolia 'Little Little Spire Russian W Asia, E Europe Spire' Sage Salvia greigii 'Pink Preference' Pink Preference Texas TX, MX Sage Salvia microphylla 'Wild Wild Watermelon AZ, MX Watermelon' Salvia Teucrium hircanicum Iranian Wood Sage Iran Thymus comosus Comosus Thyme Romania 22

Thymus praecox 'Reiter's Red' Creeping/Wild Thyme Europe Thymus praecox ssp. Arcticus Creeping/Wild Thyme Europe Thymus quinquecostatus Five-Ribbed Thyme Temperate Asia Thymus serphyllum 'Pink Chintz' Creeping/Wild Thyme Europe, W Asia, N Africa Verbascum nigrum Black Mullein Mediterranean Region

Rock Garden at Mt. Cuba Center Amsonia ciliata var. filifolia Blue Star Southeastern U.S. 'Georgie Pancake' Amsonia ciliata var. tenuifolia Fringed Bluestar Southeastern and South Central U.S. Aquilegia canadensis 'Canyon Canyon Vista Wild Eastern NA Vista' Columbine Aquilegia canadensis 'Little Little Lanterns Wild Eastern NA Lanterns' Columbine Baptisia arachnifera Hairy Rattleweed Georgia Baptisia tinctoria Yellow Wild Indigo Eastern NA Cheilanthes lanosa Hairy Lip Fern Eastern and Central U.S. Cheilanthes tomentosa Woolly Lip Fern Southern U.S. Clematic ochroleuca Erect Silky Leather- Eastern U.S. Flower Clinopodium georgianum Georgia Wild Basil Southeastern U.S. Coreopsis grandiflora var. Largeflower Tickseed Southeastern U.S. saxicola Cunila oreginoides American Dittany Eastern U.S. Delphinium alabamicum Alabama Larkspur AL and GA Delphinium carolinianum Carolina Larkspur Southeastern U.S. Diervilla lonicera Northern Bush Eastern NA Honeysuckle Eurybia avita Alexander's Rock Southeastern U.S. Aster Eurybia hemispherica Prairie Wood Aster South-Central U.S. Eurybia spectabilis Showy Aster Eastern U.S. Gelsemium sempervirens Carolina Jasmine Southeastern, South-Central U.S. and Central/South America Hypericum densiflorum Bushy St. John's Wort NA Hypoxis hirsuta Yellow Star Grass Eastern and Central NA Ionactis linarifolius Stiff Aster Eastern NA Iris verna Dwarf Iris Eastern U.S. Juniperus virginiana 'Grey Owl' Dwarf 'Grey Owl' Red Eastern U.S. Cedar Krigia montana Mountain Dwarf Southeastern U.S. Dandelion Liatris cylindracea Cylindrical Gayfeather Ontario to Missouri Liatris pilosa var. pilosa Grass-Leaf Blazing SE U.S. Star 23

Liatris squarrosa Scaly Gayfeather Eastern and Central NA Lithospermum canescens Hoary Puccoon Eastern and Central NA Lysimachia graminea Grassleaf Yellow AL Loosestrife Lysimachia lanceolata Lanceleaf Loosestrife Eastern NA Oenothera perennis 'Cold Crick' Cold Crick Sundrops Eastern and Central NA Packera antennariifolia Shalebarren Ragwort Eastern U.S., Appalachian Mtns. Phlox subulata Moss Phlox Eastern and Central U.S. Rhododendron canescens Piedmont Azalea Southeastern U.S. Rosa carolina Carolina Rose Eastern and Central NA Ruellia noctiflora Nightflowering Wild Southeastern U.S. Petunia Sedum nevii Nevious Stonecrop Southeastern U.S. Sedum ternatum Woodland Stonecrop Eastern U.S. Silene virginica Fire Pink Eastern and Central U.S. Spigelia marilandica 'Little Little Redhead Indian Southeastern U.S. Redhead' Pink Spigellia Purpleflower Pinkroot AL alabamensis/gentianoides Symphyotrichum ericoides White Heath Aster Central and Eastern NA Xerophyllum asphodeloides Turkey Beard Southeastern U.S.

Appendix D. Butterfly Planting Recommendations for Bloomfield Farm. This table lists native plants with special value to butterflies native to PA and NJ. The table specifies the plant’s scientific name, whether it is attractive to butterflies as a nectar or host plant, and which butterflies it may attract. These plants should be considered in future plantings surrounding the intensive green roof to further support the insect community on the roof. All information from this table was compiled from the North American Butterfly Association plant lists of Southeastern PA (http://nababutterfly.com/wordpress/wp- content/uploads/2014/03/pa_southeastern.pdf) and NJ (https://www.naba.org/chapters/nabanj/Butterfly_Caterpillar_Host_Plants_for_New_Jersey_Gardens.pdf).

Plant Nectar/Host Associated Lepidoptera

Tithonia rotundifolia Nectar Swallowtails

Clethra alnifolia Nectar Swallowtails, Silver-Spotted Skipper

Echinacea purpurea Nectar Eastern Tiger Swallowtail, Hairstreaks, Skippers

Agastache foeniculum Nectar Many

Ceanothus americanus Nectar Early butterflies

Daucus carota Host Black Swallowtail

Baptisia australis Host Wild Indigo Duskywing

Amorpha fruticosa Host Silver-Spotted Skipper

Urtica dioica Host Red Admiral

Viola spp. Host Great Spangled Fritillary, Meadow Fritillary

Antennaria spp. Host American Lady

Desmodium canadense Host Silver-Spotted Skipper, Hoary Edge, Southern Cloudywing, Northern Cloudywing, Gray Hairstreak

Poa spp. Host Little Wood-Satyr, Common Wood-Nymph, Peck’s Skipper, Tawny-Edged Skipper, Northern Broken-Dash, Crossline Skipper, Delaware Skipper, Hobomok Skipper,

Tridens flavus Host Common Wood-Nymph, Crossline Skipper, Little Glassywing, Zabulon Skipper

Rhus copallina Host Red-Banded Hairstreak

Ptelea trifoliata Host Giant Swallowtail 25

Cornus sericea, amomum, Host Summer Azure racemosa

Vaccinium spp. Host Striped Hairstreak, Spring Azure

Viburnum spp. Host Spring Azure

Lindera benzoin Host Spicebush Swallowtail

Juniperus virginiana Host Juniper Hairstreak

Sassafras albidum Host Spicebush Swallowtail

Pinus spp. Host Eastern Pine Elfin

Quercus spp. Host Hairstreaks and Duskywings

Betula spp. Host Red-Spotted Purple

Celtis occidentalis Host Hackberry Emperor, Tawny Emperor, American Snout, Question Mark, Mourning Cloak

Populus spp. Host Mourning Cloak, Red-Spotted Purple, Viceroy, Dreamy Duskywing