biodiverse green roofs

DESIGN GUIDELINES FOR BIODIVERSE GREEN ROOFS

2 TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING

Acknowledgements: Prepared by:Scott Torrance Landscape Architect Inc., with: Brad Bass, Scott MacIvor and Terry McGlade, in conjunction with Toronto City Planning Division

Illustrations:Grace Yang, Scott Torrance Landscape Architect Inc.

Photographs:See individual photographs

Design and Layout:Graphics and Visualization, Urban Design, Toronto City Planning Divison

www.toronto.ca/greenroofs

2013


TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING 3

Table of Contents1.0 Introduction and Background 5

2.0 Natural Heritage and Biodiversity Objectives 6

3.0 Opportunities and Constraints 8 3.1 Extensive and Intensive 8 3.2 Roof Types 10 3.3 Native Vs Non Native 10 3.4 Invasive Species 10

4.0 Design Guidelines 11 4.1 Design Factors 11 4.1.1 Depth, Topography and Composition of Growing Media 11 4.1.2 Vegetation Diversity 11 4.1.3 Structures 12 4.2 Design Strategies 13 4.2.1 Increase Depth of Growing Media 13 4.2.2 Vary Composition (Structure) of Growing Media 13 4.2.3 Provide Topographic Variety 13 4.2.4 Provide Microclimates 14 4.2.5 Diversify Plant Species 14 4.2.6 Provide Perching Habitat 14 4.2.7 Provide Nesting Opportunities 15 4.2.8 Provide Water Source(s) 15 4.3 Design Analogues 16 4.3.1 Recreate Native Landscapes 16 4.3.2 Design to Attract Specific Fauna 19 4.3.3 Design to Support Adjacent Ecosystems 22

Sources/Resources 24Appendix A: Recommended Plant Species 25Appendix B: Plant Species to Avoid 33Appendic C: Plants used by Butterflies and Caterpillers 35



About the Green Roof BylawToronto is the first City in North America to have a bylaw to require and govern the construction of green roofs on new development.

Toronto Municipal Code Chapter 492 Green Roof came into effect on February 1, 2010 and applies to most building permit applications for new development that are over 2,000m2 in gross floor area. The Bylaw requires that new development include a green roof covering between 20 and 60 percent of the roof area depending on the size of the building.

Toronto Green Roof Construction Standard Supplementary GuidelinesThe Toronto Green Roof Construction Standard Supplementary Guidelines provide designers and others with best practices, explanatory material and other green roof resources. The Supplementary Guidelines contain the following best practices which provide impetus to design to promote biodiversity:

Growth media depth over 100 mm is encouraged.

Vegetation should be: AsdefinedinASTME2400-06StandardGuideforSelection,Installation,andMaintenanceofPlantsforGreenRoofSystems NativeoradaptivefromtheSouthernOntarioarea AppropriatefortheTorontoclimateandbuildingexposure Droughtresistanttominimizetheneedforirrigation Non-monoculture

1.0 Introduction and BackgroundGreen roofs have many environmental benefits. They help reduce the effects of the urban heat island and associated energy use, manage stormwater runoff (reducing the pollutants that enter our waterways), improve air quality and beautify our city. Green roofs also provide an opportunity to create habitat and enhance biodiversity in the urban fabric of the City.

The City of Toronto has a bylaw to require the construction of green roofs on most types of new building development. The City also encourages green roofsthroughtheEco-Roofincentiveprogramandbyprovidingexplanatorytools and resources through the Citys green roof website. All green roofs in Toronto, including those required by the Green Roof Bylaw, are required to meet minimum standards which are defined in the Toronto Green Roof

Construction Standard. Additional guidance for green roof construction is found in the Toronto Green Roof Construction Standard Supplementary Guidelines. These Guidelines for Biodiverse Green Roofs identify, describe and illustrate best practices for creating habitat and promoting biodiversity on green roofs in Toronto. They are intended to support and expand the Toronto Green Roof Construction Standard Supplementary Guidelines. These guidelines are primarily designed for use by architects and landscape architects involved in designing green roofs but they may also be of interest to others who wish to understand how green roofs can be designed to enhance and support biodiversity.


Example of hybrid meadow/grassland community. Two views of Robertson Building, 215 Spadina, Toronto (McGlade, 2011)

A 2010 discussion paper on Using Green Roofs to Enhance Biodiversity in the City of Toronto reviewed literature on green roofs and biodiversity and identified opportunities, locations and strategies to enhance biodiversity and support Torontos natural heritage system by increasing the area of habitat for flora and fauna, acting as transition zones or buffers between natural habitats and the surrounding urban area and performing ecosystem services.

Green roof adjacent to High Park, Toronto (McGlade, 2011)

2.0 Natural Heritage and Biodiversity ObjectivesTheCityofTorontoOfficialPlanrecognizestheimportanceofprotecting,restoring and enhancing the health and integrity of the natural ecosystem and supporting biodiversity. These Guidelines help to implement policies in theOfficialPlanwhichseektosupportthispolicyobjective.

Toronto Official Plan Policy 3.4.1 To support strong communities, a competitive economy and a high quality of life, public and private city-building activities and changes to the built environment, including public works, will be environmentally friendly, based on:

b) Protecting, restoring and enhancing the health and integrity of the natural ecosystem, supporting bio-diversity in the City and targeting ecological improvements

Green roofs have the potential to enhance biodiversity in urban areas. In the City of Toronto, green roofs have the potential to contribute a significant area of habitat to the urban matrix. A 2005 Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto estimated that 21 percent of the total land area in the City is covered with roof and that 8 percent, or approximately 5,000 hectares of Citys land area, is covered with roof that could be suitable for green roof. The study concluded that if these areas were converted to green roof they would provide opportunities to recreate some of the habitat and restore some of the biodiversity that has been lost due to urbanization.

TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING6


When development is proposed in or near the natural heritage system, the OfficialPlanrequiresthattheproposeddevelopmentsimpactonthenaturalheritage system be evaluated and measures to mitigate negative impacts and restore and/or improve the natural heritage system be identified. Inkeepingwiththispolicy,whereagreenroofistobeconstructedinor abutting the natural heritage system, the Toronto Green Standard encourages applicants to consider providing a minimum growing medium depth of 150 millimetres (6 inches) to accommodate a greater variety of plant species, to promote biodiversity.

Torontos Natural Heritage System

Torontos Natural Heritage System is an evolving mosaic of natural features and functions across the City, including forest, wetland and meadow habitats; valley and stream corridors, the shoreline of LakeOntarioandothersignificantnatural features and is connected to natural systems outside of the City including the Greenbelt. Torontos natural heritage system is illustratedonMap9oftheOfficialPlan and is based on a Natural Heritage Study (2001) which identified and mapped the location of natural features and functions across the City.




Extensive Green Roof, 75mm depth, sedums and chives only; Victoria Park Subway Station, Toronto (Torrance, 2009)

Example of hybrid meadow/grassland community, extensive green roof, 150 mm depth at Jackman Public School, Toronto (McGlade, 2011)

Toronto Green Standardisatwo-tiersetofperformancemeasuresfor sustainable site and building design for new private and public development. The Toronto Green Standard requires green roofs on buildings included in the City of Toronto Green Roof Bylaw and encourages green roofs on other buildings.

3.0 Opportunities and Constraints

3.1 Extensive and Intensive

Green roofs can be classified as either extensive or intensive, depending on the depth of substrate used and the level of maintenance required. Most of the green roofs that have been constructed under the Torontos Green RoofBylawareextensivegreenroofs.Extensivegreenroofsgenerallyhave shallow, well drained substrates and hot dry conditions that are generally only suitable for a few drought tolerant species and minimal biodiversity. Intensive green roofs have deeper substrates that can support a greater variety of habitats and biodiversity. Green roofs can also involve a combination of the two types.


Key differences between extensive and intensive green roofs

Roofing Element Extensive Green Roof Intensive Green Roof

Growing Media/Structural Preparation

Depth of growing media generally between 50-100mm(24inches) Minimal to no irrigation Light weight Structural engineering usually not required Suitable to cover large surface areas

Depth of growing media greater than 100 mm (4 inches) Morelikelytorequireirrigation Heavier in weight Requires structural engineering Used over smaller areas or in landscaped containers

Vegetation Stressful conditions for plants requires low growing drought resistant species Can support few plant species, generally monoculture

Deeper substrate can support wider range of native plant species Can be designed to simulate greater range of plant species and habitats

Biodiversity Characteristics

Shallow substrates subject to the effects offreezingandextremedrought.Overwintering survival is low. Limited opportunity to incorporate habitat features Little opportunity for habitat functions

Deeper substrate depths buffer against the effects of freezing and extreme drought opportunities to incorporate habitat features for mobile species such as birds and insects Greater opportunity for restoration of habitat functions

Source: Using Green Roofs to Enhance Biodiversity in the City of Toronto, 2010.




3.3 Native Vs Non Native

Thereisongoingdebateabouttheuseofnativeversusnon-nativeorexoticplants. There are several arguments in favour of using native plants. Native plants are well adapted to local environmental conditions and are more likelytoformself-sustainingplantcommunitiesthatrequirelesslong-term maintenance, because they are already adapted to this climate and its extremes. Native plants also provide important sources of food and shelter for native birds, butterflies and other insects. Use of local vegetation in planting design may also allow colonization by other local species to occur morequicklyastheyarealreadyadaptedtothenativevegetation.

Therearealsoseveralargumentsinfavourofusingnon-nativeplantsprimarily because the climate on a roof is different than on the ground. It is generally hotter and drier, and many native plants do not adapt well to thisenvironment.Therearenon-nativeplantsthatarealreadywell-adaptedto growing in confined spaces, and these plants may be better suited to growing on a roof. For example Sedum varieties from alpine regions have a proventrackrecordongreenroofsandtheseplantscanstillbeusedaspartof a green roof that is designed to provide habitat for birds and insects.

3.4 Invasive Species

Certain invasive plants can colonize green roofs. These are mostly hitchhikersinsoilorplantmaterialintentionallyplantedduringinstallationbut also some plants species with very mobile seeds dispersed by wind or by birds. A species which is not typically invasive may act invasive under certain conditions (e.g., Canada goldenrod and Manitoba maple). Plant colonizers require free nutrients to get established, and a high diversity of plants can be used as a strategy to minimize free nutrients, thus reducing or eliminating the ability of invasive species to colonize a green roof. Somecolonizerslikedandelion(Taraxacum officinale) provide considerable nectarandpollenresourcesformanykindsofbeneficialinsects,asdoesbird vetch (Vicia cracca)anitrogen-fixingleguminousplantsthatimprovesaccessibility of other plant species to this essential soil element.

3.2 Roof Types

No roof necessarily presents the optimal environment for creating a biodiverse ecosystem, but where there are constraints, there are opportunities. A rooftop is already a harsher environment than what mostplantsencounterontheground-aresultofhighertemperatures,higherwindspeedsandreducedwater-holdingcapacityincomparisontomostenvironmentsexistingatground-level.Infullsun,thesestressesareexacerbated, necessitating the need for regular irrigation. Flat roofs that can support an intensive green roof may only be constrained by cost, sun or shade. Many flat roofs will become extensive green roofs duetolimitationsontheroofsweight-bearingloadand/orbudgetaryconsiderations. Flat roofs do not have significant variability in water drainage and offer lower niche diversity, and thus less opportunity for differentplantstoexploitthesenovelhabitats.Opportunitiesmayexisttovary growing media topography by adding depth on those parts of the roof that can support the additional load (e.g. above structural areas). Sloped green roofs are not as common in North America as they are in Europebecausemorestructureisrequiredtokeepthegrowingmediain place, which in turn raises cost. However, sloped roofs may allow for (or require) a wider plant palette in comparison to a topographically homogenous extensive green roof. The upper regions of a sloped roof will drain faster than lower regions, creating niches for different plant species better adapted to drier conditions (e.g. Sedums) at the high side and wetter conditions (e.g. grasses, asters) in the low areas. Gravity, wind, and dry conditions can topple loose soil and plant material, particularly since sloped roofs often do not have a parapet for added protection. In terms of moisture, adding slope is analogous to adding depth on an increasing gradient from top to bottom. Sloped roofs may also provide areas of partial to full shade if they use shed or hip configurations. This necessitates plant species selection to withstand these varying light conditions.



In Toronto, the diversity of plants that can survive increases dramatically whendepthofgrowingmediaincreasesfrom100mmto150mm(46inches). Green roof substrate depths above 100mm (4 inches) or more willhelptoavoidsignificantdie-backinthewinterorduringhotsummermonths. Topographic variation in substrate depth across a green roof is also a way to increase biodiversity by creating a series of different microclimates, and subsequently microhabitats, within the same green roof zone. Thin substrate areas allow sparse vegetation to develop, whereas small hills or mounds of thicksubstratesupporttaller,denservegetation.Depthcanonlybeaddedon those parts of the roof that can support the additional load. Composition of the growing media can play a role in supporting biodiversity by varying the granule size of the substrate. Recreating native soil structure, or aggregate composition may also be considered, although little research has been completed on this subject. Gravel can also be used on bare areas on a roof to create habitat diversity however the Green Roof Bylaw restricts the use of substrate based extensive green roofs due to the requirement of 80percentcoverageandnoxiousweedrestriction(ifself-seedingistobereliedupon).Onestrategywouldbetomeettheminimumarearequiredby the Green Roof Bylaw and achieve 80 percent coverage, while providing othernon-plantedareastoallowself-seeding.Removalofnoxiousweedsfrom these areas would need to be part of the ongoing maintenance plan.

4.1.2 Vegetation DiversityThe vegetation layer of a green roof plays a significant role in fostering biodiversity. Maximizing the diversity of plant species and plant life forms (succulents, herbaceous perennials, woody plants, coniferous, deciduous, etc.) has many benefits, increasing the opportunities for pollination and food, shade, nesting, perching, nutrients, etc. Large roofs or roofs with high load bearing capacity provide the greatest opportunity for diversity by

Aggressiveinvasivespeciessuchasgarlicmustardandbuckthorn,whichare a threat to urban ecosystems. typically, these plants do not become established on green roofs due to the elevation, substrate depth and nutrient profile of green roofs.

Alistofrecommendedplantspecies(nativeandnon-native)isprovidedinAppendix A. Plants to avoid are found in Appendix B.

4.0 Design Guidelines

4.1 Design Factors

Therearethreedesignfactorsthathavebeenlinkedtothecreationofbiodiverse green roofs: Variationindepth,topographyandcompositionofgrowingmedia, Vegetationdiversity,and Structurestocreatenichespacesfororganisms

These three factors are described and illustrated below.

4.1.1 Depth, Topography and Composition of Growing Media

Depth of growing media or substrate is a considerable constraint on the variety of habitats that can be created on a green roof. Roof environments are subjected to many stresses such as intense temperature and moisture changes, so shallow substrates can intensify the already extreme ecological conditions. In general, as the depth of growing media increases, the opportunity to promote biodiversity also increases, simply because a greater range of plant species and plant types can be accommodated. Installation costs (both for the vegetated assembly and the structure to support it) increase as depth of growing media increases. Maintenance and irrigation requirements may increase as well for deeper roofs.


Recirculating bubbler fountain with no open water on green roof at 30 College Street,

Toronto (Torrance, 2011)

permitting a greater range of vegetation type and size, including trees and shrubs, but extensive green roofs provide excellent opportunities to create grassland communities. The most common extensive green roofs are planted with sedums. Establishmentofmonoculturegreenroofswillgenerallynecessitategreatermaintenance and careful monitoring to ensure proper viability of the single species. 4.1.3 Structures

The use of structures is a simple approach that can be used to manipulate andincreasetheutilizationoftheroofashabitat.Onetechniquethatcan be integrated almost anywhere on the roof is the addition of medium to large natural objects, such as branches or stones (these may need to be fastened down), or even rubble, all of which help to create different microclimates and microhabitats which may lead to greater species diversity. Similarly, branches can provide physical connections and shady habitats and serve as resting sites for birds to perch and as nesting structures. Bird or bat boxes can also be added to encourage species to nest and breed.




nestingandtocollectmudfornestingmaterial.Earthwormswouldneedaloose, coarse, more organic growing media than typical green roof mineral mixes provide to survive. High organic growing media can be combined with loworganic,mineral-basedgrowingmediaacrosstheroof.Gravelcanalsobe used on bare areas on the roof.

vary granule size

vary mixtures

incorporate bare areas of gravel

4.2.3 Provide Topographic Variety

Topographic diversity increases soil depth and microclimatic variation. Sloped surfaces are typically drier at the top and wetter at the bottom. This variation creates an opportunity for different plant selection to correspond tothismicro-hydrologicalregime.Topographicdiversitycanalsobeimplemented using different heights of edging, modules and planters.

4.2 Design Strategies

4.2.1 Increase Depth of Growing Media

In Toronto, The diversity of plants that can survive increases dramatically when the depth of substrate (growing media) is increased from 100 mm to150mm(4to6inches).Oneoptionistoincreasethedepthacrosstheentire roof, an alternative is to increase the depth of substrate on the parts of the roof that can support the additional load (e.g., above structural areas) and provide greater planting diversity on these areas.

A list of plant species and minimum growing depth is provided in Appendix A.

4.2.2 Vary Composition (Structure) of Growing Media

Structure can play a role in supporting biodiversity by varying the granule size of the aggregates in the substrate and the spread of different mixtures upon the roof area. Soils often have a particular distribution of granules, and native soils can be analyzed in order to reproduce the range of granularity. Varying the composition of growing media creates opportunities for greater diversity of plant species and habitats, most notably insects and soil nematodes. For instance, some species of spiders, solitary bees and pest controllingwaspsneedbare,non-compacted,smallparticulatesoilareasfor


4.2.5 Diversify Plant Species

Maximizing the diversity of plant species and plant life forms (succulents, herbaceous perennials, woody plants, coniferous, deciduous, etc.) has many benefits, increasing the opportunities for pollination and food, shade, nesting, perching, nutrients, etc. Depending on maintenance levels, which are typically minimal on green roofs, succession of plants overtime must be considered as a natural consequence (or benefit) of a diverse planting strategy.

4.2.6 Provide Perching Habitat

Objects,suchasrocks,logs,branchesorconstructedelementscanbeintegrated into green roofs to attract birds and insects to perch. Some objects, such as logs and branches, may need to be secured to the roof. Metal should be avoided due to heat absorption.

rocks

forbs, grasses and shrubs

branches and platforms

logs

4.2.4 Provide Microclimates

Objects,includingbuildingelements,providemicroclimaticopportunitiesinthe typically uniform full sun and dry condition found on green roofs. Areas in shade and below objects will be cooler and moister, providing habitat diversity opportunities, especially for insects and soil organisms.

rocks

plants

lots

buildings elements




4.2.8 Provide Water Source(s)

Water is one of the principle limiting resources for most species that would otherwise be able to use green roofs as permanent habitat. These effects are exacerbated given that green roofs are hotter and more exposed than mostground-levelhabitat.Puddlesorvernalpoolswillnotformorlastlong.For example, many bird species may find green roofs to be suitable nesting space,butoncechickshatch,periodsofdroughtcanbefatal.Asourceofwater can be provided in two ways: either pumped or collected. Pumped and recirculated water features require energy and regular maintenance (cleaning, topping up with fresh water, seasonal closing, etc.). Rainfall can be collected in depressions and basins. Maintaining water on a roof, either natural from precipitation or artificially (with a pump or fresh water supply) may not be desirable from a building science perspective and can create habitat for mosquitoes.

basins

bird baths

water features

naturally pitted cap rock

4.2.7 Provide Nesting Opportunities

Elementstoencouragenestingopportunitiesforbirdsandinsectscanbeintegratedintogreenroofs.Someinsectsandbirds(e.g.killdeer)usebareareas of soils and gravel for nesting. Bird and bee houses require regular cleaning and maintenance if they are utilized. Some objects may need to be secured to the roof.

Tall grasses and shrubs

Birdhouses

Logs and branches

Open soil areas

Bee nest boxes



4.3 Design Analogues

4.3.1 Recreate Native Landscapes

Green roofs can be designed to mimic almost any habitat and also provide an opportunity to recreate specific native landscapes. Habitats such as grasslands and herb communities are well suited to intensive roofs.

Green roofs have been found to be broadly analogous to certain types of landscapes,fromwhichplantsareseeminglypre-adaptedtotheharshgreenroof environment. Selecting plants from habitats that exhibit microclimatic characteristics similar to green roofs increase chances of discovering suitableplants.Theseincludepermanentlyopenhabitatssuchasrockyoutcrops, cliffs, dunes, heathlands, and alvars.

Green roof designed with many different depths of growing medium, as well as open soil areas, in order to support a diversity of trees, shrubs, grasses, forbs and succulents. ESRI Canada, Toronto (Torrance/Mulligan, 2010)

Green roof with 75mm to 500mm growing depths, deep enough to support a variety of native prairie plants. Design includes structures for perching and nesting and water feature to attract wildlife. Native Child & Family Services, Toronto (Torrance, 2009)



palette. An overarching philosophy of maximizing species diversity and then allowing plants to colonize themselves will help build resiliency through adaptability into the green roof ecosystem. A list of plants and minimum soil depths is provided in Appendix A.

Tallgrass Prairie, Walpole Island First nation, Essex County, Ontario

(J.L. Riley from Ecological Land Classification for Southern Ontario, 1998)

Four of these habitat types are potential analogues for green roof plant selection and growing media composition: tallgrass prairie, alvars, fens and sand barrens.

Tallgrass Prairie

Defining Characteristics: Grasslandwithvariablecoverofsmallwoodyshrubsand open-growntrees Subjecttoseasonalextremesinmoistureconditions Toleratesspringfloodingandsummerdrought Regeneratedbyfiredisturbance

Growing Media Composition: Unconsolidatedmineralsubstrateswithasoildepthof>150mm Typicallyconsistsofwell-drainedsands,loams,andsometimesclay

Plant Selection: Dominatedbyprairiegrasses,forbs,sedges,smallwoodyshrubsand open-growntrees

Other Considerations:It is not wholly accurate to use the tallgrass prairie habitat as a template for green roof design, as species diversity is lower and conditions on extensive green roofs vary considerably from those found in a natural tallgrass prairie habitat. Soil depth is less then found in the natural habitat, conditions tend to be drier and windier and soil quality is poorer. For these reasons, grasses cannotestablishtheirrootsasextensively.Firedisturbanceanaturalphenomenonthatsupportsvegetativeregenerationisalsoabsentongreen roofs.

An alternative is to create a hybrid meadow/grassland plant community. If only a 100mm soil depth can be achieved, a much more limited number of plant species can be used. A minimum soil depth of 150 mm will support a greater diversity of species and thus a more comprehensive planting



Fens

Defining Characteristics: openhabitats wetalmostallyear soilsarehighinorganiccontent(aresultofdecomposingplant material), contain peat, and are often saturated supportawidediversityofplantandinsectspecies

Growing Media Composition: organic-richsoils,asdeepaspossible,withsomeaggregates

Plant Selection: dominatedbysedges,grasses,forbs,mosses,andsomewoodyplants

Other Considerations:Buildings that produce high volumes of wastewater (e.g. air conditioners, industrial processes), are lower to the ground and less exposed, are good candidates for incorporating fen habitat analogs into their green roof design. It is not economically or environmentally feasible to use fen habitat as templates for green roof design if only potable water is available for irrigation.Thebeststrategyistoroutewastewaterontotheroof,keepingitsaturated as often as possible during the spring, summer, and fall seasons.

Fen, Emily River Fen, Victoria County, Ontario (J.L. Riley from Ecological Land Classification for Southern Ontario, 1998)

Alvars Defining Characteristics: naturallyopenlandscapeswithlittleornotreecover patchydistributionsofloamyandsandysoilsatheterogeneousdepths soiltextureisgenerallyaloam

Growing Media Composition: shallowdepths(lessthan20cm) depressionsinterspersedamongbarerockypatches generallywetinthespringandseverelydryinthemid-summer containdistinctivespecieswhichareadaptedtoharshgreenroof environments, as well there are many rare species

Plant Selection: patchydistributionofgrassesandforbs

Other ConsiderationsAlvars have patchy distributions of loamy and sandy soils at heterogeneous depths, a result of natural depressions in the underlying limestone bed, andsurroundingexposedrock.Soiltextureisgenerallyaloam.Greenroofsusing alvar habitat analogs as a design focus will want growing media with organic matter, shallow depths (less than 20cm) and depressionsinterspersedamongbarerockypatches.Thesehabitatanalogswillneedtobegenerallywetinthespringandseverelydryinthemid-summer.

Alvar, Bruce Alvar Nature Reserve, Bruce County, Ontario (J.L. Riley from Ecological Land Classification for Southern Ontario, 1998)


TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING

4.3.2 Design to attract specific fauna

Green roofs can be designed to attract and support certain fauna, typically birds and insects, whether they are native, rare or require stopping points on a migration route. This can be done by designing the roof to provide certain features that these fauna require on the landscape, but not necessarily the complete habitat.

Birds

Urban development and loss of habitat have impacted travel distances, expended energies, and reduced the availability of food sources for migratory birds passing through. Green roofs provide vegetation where there would otherwise be none and create temporary foraging habitat for local and migratory birds. Grasses and herbaceous plants that produce numerous seed heads can provide invaluable energy sources for migratory birds. Perches and nesting boxes can provide opportunities for resting and breeding.

Sand Barrens Defining Characteristics: restrictedtreegrowth fullexposuretosun poorsoilquality

Growing Media Composition: sandyandwell-draining heterogeneousdepthsandamixoflargeraggregates

Plant Selection: slow-growingshrubbygrasslandandheathlandmosaics,dottedwitha high diversity of herbaceous plants droughttolerant

Other Considerations:It is recommended to not design an entire roof after the Sand Barren community,assandysoilsaremorelikelytoerodefromtherooftopbywind. Instead, patches of sand barren habitat can be considered. When patches are planted, use soil stabilizers and erosion control netting until the plants establish to minimize soil loss.

Sand Barren, Giants Tomb Island Nature Reserve, Simcoe County, Ontario (J.L. Riley from Ecological Land Classification for Southern Ontario, 1998)

19



Green roof elements designed to attract birds, providing nesting and perching opporunities, at University Hospital, Basel, Switzerland (Bass, 2003)

Migratory Birds in the City of Toronto

A 2009 report Migratory Birds in the City of Toronto identifies the potential of green roofs as temporary stopover habitat for migratory species especially when flying over extensive urbanized areas en route to more suitable habitat. Green roofs might also pose a hazard to birds passing over the city by increasing its chance of colliding with reflective glass adjacent to the roof. The Citys Bird-Friendly Development Guidelines can be implemented on portions of buildings adjacent to green roofs to help reduce bird fatalities.

Migratory Birds in the City of Toronto

Bird-Friendly Development Guidelines



provide permanent nesting space for these species on rooftops.

Bee nesting box, 410 Richmond Street, Toronto (MacIvor, 2011)

Other Insects

Green roofs may provide habitat for pollinating insects such as bees, flies, and butterflies, but also other functionally important invertebrates. These include those critical for nutrient cycling and decomposition, such as springtails, millipedes, beetles, and worms; predation of pest species by spiders, solitary wasps, dragonflies and damselflies; and many asfoodforotherdesirablespeciesincities,likebirds.Althoughmanyurban invertebrates may only use a green roof habitat temporarily, some species,particularlythosesoil-dwellersimportantfornutrientcyclingand decomposition can be permanent inhabitants, and so require some consideration in green roof planning to ensure populations can colonize and persist.Greatergrowingmediadepths,plantcanopy,andfeatureslike logs,

Bees

There are many species of pollinators, including bees, flies, moths, and butterflies that can incorporate green roofs into their foraging ranges. Bees, in particular, being highly mobile, mostly polylectic (meaning, they can visit manydifferentkindsofflowers),andadaptedtospatiallyseparatenestingand foraging resources, are very well suited to receive support from green roofs designed with foraging and nesting resources in mind. This is all the more important as bee populations decline worldwide. Bees need flowers for pollen and nectar, and green roofs with diverse plant palettes to prolong blooming are most valuable. In cities, wild bee diversity seems to positively respond to increases in total plant diversity. Roofs planted entirely with Sedum, or similar species, also provided pollen and nectar for many bees, but only flower for only a short period so act only as temporary resources.

Ifoneoftheobjectivesistokeephoneybeesonthegreenroof,watershouldbeavailableatalltimesinbucketsorpans,anopenrainbarrel,orpreferablya continuous fresh water source. Honeybees need to collect large amounts of water to maintain healthy hives. The water is used to dilute honey to feed to larva, and to cool the hive through evaporation in hot weather.

Interestingly,manypollinatorsarehighly-mobileandadaptedtospatiallyseparated foraging and nesting areas. As such, many bees can reach green roofs and once there may find permanent (nesting and forage) or temporary (forage only) refuge; thereby incorporating green roofs into their foraging ranges. Since approximately 60 percent of Torontos bee species nest in the ground, green roofs designed to support bees might include areas of bare soil, soil topographic heterogeneity, and a plant community with an extended floweringperiod.Manyotherbeesnestinstemsandpre-existingcavities,so maintenance that includes not cutting plant stems down to the soil (leave 150 mm (6 inches) or more, if possible), adding dead wood as a design element, or even nestboxes, comprised of holes drilled into wood, or bundled reeds or paper tubes plugged at one end added as a roof feature could



largestonesorpaversareallimportanttoreduceexposureandkeepsomeareasslightlymoredampandcool.Thisisessentialforsurvivalofsoil-dwellingandlow-mobilityspeciesduringthedriestandhottesttimesoftheyear.

Manyhighly-mobile,specieslikebees,butterflies,dragonflies,andbirdscan incorporate one or more green roofs, both intensive and extensive, into their foraging range. These species may source requirements for survival and reproduction from a green roof, such as food (pollen, nectar, prey), or shelter (nesting material, locations, oviposition and metamorphosis sites).

Species that find permanent refuge on an extensive green roof may have low resource requirements for survival and successful reproduction. For example,somesmallground-nestingeusocialandsolitaryLasioglossumbeescanprovisionlarvaewithpollenandnectarinveryshallow,well-draining sunny soils. These bees are very effective pollinators, but due to their small size can meet all of their foraging requirements from smallpatchesoffloweringplantsofdifferentspecies.Otherdesirable,permanently inhabiting green roof species include spiders, predatory beetles, and solitary wasps each of which effectively collect and feed on pest insects that inflict damage and harm green roof plants.

A list of plants used by butterflies and caterpillers is provided in Appendix C.

4.3.3 Design to support adjacent ecosystems

Green roofs located near or adjacent to natural heritage areas can be designed to expand and support these neighbouring ecosystems. Green roofs can act as transition zones or buffers between natural habitats and the surrounding urban area and perform ecosystem services such as providing food for pollinators and resting, feeding and breeding space for local and migratory birds. Green roofs located near or adjacent to natural heritageareasshouldlooktohowtheirdesigncanenhanceandimprovethe condition of the natural habitats. For example, new development

close to a ravine could specify plants that will create an edge condition to the ravine and use existing plant communities to inform the selection of appropriate species on the roof to effectively expand the planted area onto the tableland.

The table on the following page outlines design objectives and strategies for green roofs in specific locations in the City of Toronto.

Design Objectives and Strategies for Green Roofs in Specific Locations in Toronto

Extensive Green Roof Adjacent to Rosedale Ravine, Toronto (Torrance, 2008)



Green Roof Location Objectives Design Strategies Species for Conservation or Protection

Areas adjacent to forest habitat (e.g., river valleys, HighPark,RougePark).

Enhance/bufferadjacentecozonesandlinkgreenroofsto forest ecosystems at grade level. Beneficial matrix influence through climate and hydrological mitigation to buffer adjacent forest ecosystems.

Provide perching/ breeding/feeding opportunities for migratory birds, butterflies and insects.

Provide habitat for native plants.

Create higher order climax ecosystems; use small shrub and tree species.

Enhancepropertyperimeterregions at grade level to scale up available shrubs and other forest constituents.

Design for aggregations of green roofs on clusters of buildings.

Forest Interior birds, rare plants, native shrubs/small trees, pollinators including butterflies (along with other trophic benefactors eg. microbial soil constituents).

AreasadjacenttoLakeOntarioshoreline,rivervalley corridors.

Extendperching/breeding/feeding zones for migratory birds, butterflies and insects.

Provide habitat for native meadow/prairie plants

Meadow grasses (native and non-native)perennials+tallgrass prairie species; also try pre-vegetatedmatsystemswithaugmentations in substrate depths/shapes/ mounds where practical. Include plants that produce abundant seeds to feed early spring migrants.

Migratory birds and butterflies, native plants, insects and other pollinators (along with other trophic benefactors).

Alvar species.

Areas adjacent to meadow habitat (e.g., along hydro corridors).

Extendmeadow/grasslandhabitats and support zones for migratory birds, butterflies and insects.

Provide habitat for native meadow/prairie plants.

Meadow, grasslands or pre-vegetatedmatswithaugmentations to substrate depth as practical.

Meadow plants, grass and shrubland birds, butterflies and invertebrates.

Alvar species and possibly some meadow marsh species where water is retained more.

Source: Using Green Roofs to Enhance Biodiversity in the City of Toronto, 2010.

Design Objectives and Strategies for Green Roofs in Specific Locations in Toronto



Sources / Resources

Bird-Friendly Development Guidelines. 2007. City of Toronto.http://www.toronto.ca/planning/environment/guidelines.htm

City of Toronto Natural Heritage Study. 2001. City of Toronto and Toronto and Region Conservation Authority.http://www.toronto.ca/planning/environment/pdf/natural_heritage/natural_text1.pdf

Ecological Land Classification for Southern Ontario. 1998.FirstApproximationandItsApplication.H.T.Lee,W.D.Badowsky,J.L.Riley,J.Bowles,M.Puddister,P.Uhig,S.McMurry.1998.OntarioMinistryofNaturalResources.SouthcentralScienceSection,ScienceDevelopmentandTransferBranch.SCSSFieldGuideFG-02.

Migratory Birds in the City of Toronto.2009.PreparedforTorontoCityPlanning.PreparedbyNorth-SouthEnvironmentalInc.andDougan&Associates. http://www.toronto.ca/planning/environment/pdf/migratory_birds_15aug09_small.pdf

Toronto Green Roofshttp://www.toronto.ca/greenroofs/index.htm

Toronto Green Roof Construction Standard (Article IV of Toronto Municipal Code Chapter 492 Green Roof)http://www.toronto.ca/legdocs/municode/1184_492.pdf

Toronto Green Roof Construction Standard Supplementary Guidelines.http://www.toronto.ca/greenroofs/pdf/GreenRoof-supGuidelines.pdf

Toronto Green Standardhttp://www.toronto.ca/planning/environment/index.htm

Toronto Municipal Code Chapter 492 Green Roofhttp://www.toronto.ca/legdocs/municode/1184_492.pdf

Toronto Official Plan. 2010http://www.toronto.ca/planning/official_plan/pdf_chapter1-5/chapters1_5_dec2010.pdf

Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto. 2005. Prepared For City of Toronto and OntarioCentresofExcellenceEarthandEnvironmentalTechnologies(OCE-ETech).PreparedByRyersonUniversityProfessorsDr.DougBanting,ProfessorHiteshDoshi,Dr.JamesLi,Dr.PaulMissiosandStudentsAngelaAu,BethAnneCurrie,MichaelVerrati.http://www.toronto.ca/greenroofs/pdf/fullreport103105.pdf

Using Green Roofs to Enhance Biodiversity in the City of Toronto. 2010. A Discussion Paper Prepared for Toronto City Planning. Beth Anne Currie and Brad Bass. http://www.toronto.ca/greenroofs/pdf/greenroofs_biodiversity.pdf



Appendix A: Recommended Plant Species

Plant species should be selected first for their ability to survive the conditions they will grow in, considering: depthofgrowingmedia slopeofroof,ifany amountofsunlightavailable typeofirrigationthatwillbeprovided(manual,automatic,none) windexposure maintenancelevels location(i.e.adjacenttonaturalheritageareaornot) program(desiredlook,approach,programdesired) hardinesszone(dependingonrooflevel,atleastonezonehardierthanTorontoshardinesszoneof6) availabilityinthenurserytrade conformancewithGreenRoofBylaw Successionofplantsovertime

Once plant species are determined based on the above criteria, the type of growing media should be selected: loworganicmattercontenti.e.FLL,10%byweight Theuseofnativeandadaptivespeciesshouldbemaximized.

Based upon data collected in 2004 and 2005, the Toronto and Region Conservation Authority developed a list of native plants for a green roof environment in Toronto: http://www.toronto.ca/greenroofs/pdf/plant_suggestions2007.pdf. The following plants are recommended for use in Toronto green roofs:

Native GrassesBotanical Name Common Name Min. DepthBouteloua curtipendula Side-oatsGrama 150mmBouteloua gracilis Blue grama grass 100-150mmCarex Pennsylvannia,Nigra Sedge 150mmChasmanthium latifolium NorthernSeaOats 100-150mmDeschampsia cespitosa Tufted Hair Grass 100-150mmPanicum virgatum Switch Grass 100-150mmSchizachyrium scorparium Little Bluestem 100-150mm



Native ForbsBotanical Name Common Name Min. DepthAsclepias tuberose ButterflyMilkweed 150mmAster laevis Smooth Aster 150mmCampanula rotundifolia Harebell 150mmEchinaceapallida Pale Purple Coneflower 150mmEpilobiumangustifolium Fire-weed 150mmEupatoriumpurpureum Joe-PyeWeed 150mmEupatoriumperfoliatum Boneset 150mmGentiana andrewsii Bottle Gentian 150mmGeum triflorum PrairieSmoke 150mmHedyotis longifolia Long-leavedBluets 150mmLiatris cylindracea Cylindric Blazing Star 150mmLiatris spicata DenseBlazing-star 150mmLobelia siphilitica Great Blue Lobelia 150mmLobelia cardinalis Cardinal flower 150mmLupinus perennis Wild Lupine 150mmLysimachia quadriflora Prairie Loosestrife 150mmMaianthemum stellatum Starry False Solomons Seal 150mmMonarda didyma Beebalm(OswegoTea) 150mmMonarda fistulosa Wild Bergamot 150mmPenstemon digitalis Foxglove Beardtongue 150mmPolygonatum pubescens Downy Solomons Seal 150mmPhysostegia virginiana ObedientPlant 150mmRudbeckiahirta Black-eyedSusan 150mmRatibida pinnata Gray Headed Coneflower 150mmSolidago ptarmicoides Upland White Goldenrod 150mmSolidago squarrosa Stout Goldenrod 150mmVerbena simplex Slender Vervain 150mmVerbena stricta Hoary Vervain 150mmVeronicastrum virginicum Culvers Root 150mm

Native EvergreensBotanical Name Common Name Min. DepthJuniperuscommunisvar.depressa CommonJuniper 300mmJuniperushorizontalis CreepingJuniper 300mmThuja occidentalis White Cedar 300mm



Native Woody PlantsBotanical Name Common Name Min. DepthAmelanchier laevis SaskatoonBerry 200mmAmelanchier stolonifera Smooth Serviceberry 200mmAronia melanocarpa Chokeberry 200mmCephalanthus occidentalis Buttonbush 200mmCelastrus scandens Bittersweet 200mmCladrastis lutea Yellowwood 200mmCornus alternifolia Pagoda Dogwood 200mmCornus amomum SilkyDogwood 200mmCornus canadensis Bunchberry 150mmCornus racemosa Grey Dogwood 200mmCornus sericea RedOsierDogwood 200mmDiervilla lonicera BushHoneysuckle 200mmHamamelis virginiana Witch Hazel 200mmHypericumkalm.Kalms St.JohnsWort 200mmIlex verticillata Winter Berry 200mmMyrica pennylvanica Bayberry 200mmParthenocisus virginiana Virginia Creeper 200mmPhysocarpus opulifolius Ninebark 200mmRhus aromatica Fragrant Sumac 200mmRhus glabra Smooth Sumac 200mmSalix exigua Sandbar Willow 200mmSambucus canadensis GreenElder 200mmSambucus pubens ScarletElder 200mmSpirea alba Narrow Leaf Meadowsweet 200mmSpirea tomentosa Steeplebush 200mmSymphoricarpus albus Snowberry 200mmViburnum dentantum Arrowwood 200mmViburnum lentago Sheepberry 200mmViburnum trilobum Highbush Cranberry 200mmVitis riparia RiverbankGrap 200mm



Non-Native GrassesBotanical Name Common Name Min. DepthCalamagrostisXacutifloraKarlFoerster KarlFoersterFeatherReedGrass 150mmCalamagrostisXacutifloraOverdam OverdamFeatherReedGrass 150mm

Non-Native ForbsBotanical Name Common Name Min. DepthAstilbe chinensis Chinese Astilbe 150mmAllium shoenoprasum Chives 100-150mmBergenia cordifolia Bergenia 150mmCentaurea montana Bachelors Button 100-150mmCerastium tomentosum Snow-in-Summer 100-150mmDianthus deltoides MaidenPinks 100-150mmEchinaceapurpurea EasternPurpleConeflower 150mmEchinopsritro Blue Globe Thistle 150mmGeranium sanguineum Bloody Cranesbill 100-150mmHemerocallis sp. Daylily 100-150mmHosta sieboldiana Siebold Hosta 150mmIris setosa Dwarf Arctic Iris 100-150mmLavandula angustifolia EnglishLavender 100-150mmPhlox paniculata Summer Phlox 100-150mmPhlox subulata Moss Phlox 100-150mmRudbeckianitida Coneflower 150mmThymus citriodorus Lemon Thyme 100-150mmThymus serphyllum Creeping Thyme 100-150mmVeronica incana Silver Speedwell 150mm

Non-Native Woody PlantsBotanical Name Common Name Min. DepthCornus alba Sibirica Pearls 200mmCornus sericea isanti IsantiRed-OsierDogwood 200mmHydrangea arborescens Annabelle 200mmPotentilla fruticosa Bush Cinquefoil 200mmPotentillatridentataNuuk Wineleaf Cinquefoil 200mm



Prunus X cistena Purple Leaf Sand Cherry 200mmRhodendron Aglo Aglo Rhododendron 200mmSpirea bumalda Goldmound Spirea Goldmound 200mmSyringa vulgaris Common Liliac 200mmWeigela florida French Lace French Lace Weigela 200mm

Forbs Full SunBotanical Name Common Name Min. DepthAchillea sp Yarrow 100-150mmAnaphalis margaritacea Pearly everlasting 150mmAquilegia Canadensis Columbine 100-150mmAsclepias tuberosa ButterflyMilkweed 150mmAster laevis Smooth Blue Aster 150mmAsternova-angeliae NewEnglandAster 150mmCampanula rotundifolia Harebell, Bluebell 150mmEchinaceaangustifolia Narrow Leafed Coneflower 150mmEchinaceapallida Pale Purple Coneflower 150mmEupatoriummacpurpureum JoePyeWeed 150mmEquisetumhymenale Horsetail Grass 100-150mmFragaria virginia Virginia Strawberry 100-150mmHelianthus salicifolius Willow-leavedSunflower 150mmHelenium autumnale Common sneezeweed 150mmLiatris cylindracea Cylindric Blazing Star 150mmLiatris spicata DenseBlazing-star 150mmLobelia siphilitica Great Blue Lobelia 150mmLobelia Cardinalis Cardinal flower 150mmMonarda didyma Beebalm(OswegoTea) 150mmMonarda fistulosa Wild Bergamot 150mmPenstemon digitalis Foxglove Beardtongue 150mmPhysostegia virginiana ObedientPlant 150mmRudbeckiahirta Black-eyedSusan 150mmVerbena simplex Slender Vervain 100-150mmVerbena stricta Hoary Vervain 150mmVeronicastrum virginicum Culvers Root 150mm

Non-Native Woody Plants (Continued)



Non-Native Plants - Full SunBotanical Name Common Name Min. DepthAstertararicusJindai Dwarf Tatarian Aster 150mmAster tararicus Tartarian Aster 150mmBergenia Cordifolia Heart-leavedBergenia 150mmCentaurea Montana Mountain Bluet 150mmCerastium tomentosum Snow-in-summer 100-150mmCoreopsis tripteris TallTickseed 100-150mmCoreopsis verticillata Thread-leavedCoreopsis 100-150mmDianthus deltoides MaidenPinks 100-150mmCampion (Silene) MossPinks 100-150mmEchinaceapurpurea Purple Coneflower 100-150mmEchinopsritro Globe Thistle 150mmEuphorbia Crown-of-thorns 100-150mmGeranium maculatum Wild Geranium 100-150mmGeranium psilosteum Armenian Cranesbill 100-150mmGeranium pratense Meadow Cranesbill 100-150mmGeranium sanguineum Bloody Geranium 100-150mmGaillardia grandiflora Blanketflower 100-150mmGeum Avens 100-150mmHemerocallis Daylily 100-150mmHosta sieboldiana (Sun Loving Hostas) 150mmIris germanica German Iris 100-150mmIris setosa Dwarf Arctic Iris 100-150mmLavandula angustifolia EnglishLavender 100-150mmLeucanthemum X superbum Shasta Daisy 100-150mmNepeta X faassenii Catmint 100-150mmPhlox subulata Creeping Phlox 100-150mmRudbeckia Goldsturm Coneflower 100-150mmSalvia X sylvestris Sage 100-150mmSedum album Carpet Stonecrop 100-150mmSedum ellacombianum Sedum ellacombianum 100-150mmSedum ewersii PinkMongolianStonecrop 100-150mmSedumhybridAutumnJoy AutumnJoy 100-150mmSedumkamschaticum Sedumkamschaticum 100-150mm



Sedum sexangulare Tasteless Stonecrop 100-150mmSedum spectabilis Showy Stonecrop 150mmSolidago sphacelata Dwarf Goldenrod 150mmX Solidaster luteus Solidaster 100-150mmSedum spurium Dragons Blood 100-150mmStachys byzantina Lambs ears 100-150mmThymus serphyllum Creeping Thyme 100-150mmThymus X citriodorus Lemon Thyme 100-150mmVeronica longifolia Long-leavedSpeedwell 100-150mmVeronica noveboracensis Ironweed 100-150mm

Non-Native Plants - Full Sun (Continued)



Noxious Weeds (Ont. Regulation 1096 Weed Control Act)

Item Common Name Botanical Name

1. Barberry, common Berberis vulgaris L.

2. Buckthorn,European Rhamnus cathartica L.

3. Carrot, wild Daucus carota L.

4. Colts-foot Tussilago farfara L.

5. Dodder spp. Cuscuta spp.

5.1 Giant Hogweed Heracleum mantegazzianum

6. Goats-beardspp. Tragopogon spp.

7. Hemlock,poison Conium maculatum L.

8. Johnsongrass Sorghum halepense (L.) Persoon

9. Knapweedspp. Centaurea spp.

10. Milkweedspp. Asclepias spp.

11. Poison-ivy Rhus radicans L.

12. Prosomillet,black-seeded Panicum miliaceum L. (black-seededbiotype)

13. Ragweed spp. Ambrosia spp.

14. Rocket,yellow Barbarea spp.

15. Sow-thistle,annual,perennial Sonchus spp.

16. Spurge, Cypress EuphorbiacyparissiasL.

17. Spurge, leafy EuphorbiaesulaL.(complex)

18. Thistle, bull Cirsium vulgare (Savi) Tenore

19. Thistle, Canada Cirsium arvense (L.) Scopoli

20. Thistle, nodding, spp. Carduus spp.

21. Thistle, Russian Salsola pestifer Aven Nelson

22. Thistle, Scotch OnopordumacanthiumL.

23. Vetchling, tuberous Lathyrus tuberosus L.

http://www.e-laws.gov.on.ca/html/regs/english/elaws_regs_901096_e.htm

Appendix B: Plant Species to Avoid

CityofTorontoBylawNo.583-2009492-9LstatesthatvegetationonagreenroofshallnotincludeanynoxiousweedsasdefinedinOntarioRegulation 1096 under the Weed Control Act (see table below). In addition the following plant species also should be avoided:

Medicago spp.(BlackMedick),Capsella sp. (Shepherds Purse), Cerastium sp.(Chickweeds)willeachgrowexponentiallyandthen undergomassivedie-offduringperiodsofdrought.Eachsetlarge numbers of seeds and have incredible spread.

Digitaria spp. (Crabgrasses), Alliaria sp. (Garlic Mustards), Ambrosia sp. (Ragweed) all very drought tolerant, but highly competitive and spread very fast.

Chenopodium album(LambsQuarter)-verydroughttolerant- stayinggreenwheneverythingelseisbrown-butsetsmanyseeds and spreads fast.


Appendix C: Plants Used by Butterflies and CaterpillarsThese are some common plants used by butterflies for nectar and by caterpillars as food in the Toronto area.This list is not comprehensive. Where several species (spp.) in a genus are suitable, only the genus name isgiven (e.g., Asclepias spp. for various milkweed species). The status of different species in a genus may vary(i.e., some may be invasive while others are not). Some species may not be suitable because they can be aggressiveor invasive.

Native plants grew in our area before the arrival of Europeans. Cultivated plants are introduced species that grow in our area only with human assistance. Naturalized plants are introduced species that survive without human assistance and now reproduce here. Invasive plants are naturalized species that negatively impact native biodiversity by reproducing aggressively

and taking over natural habitats, to the exclusion of other plants.spp. = various species in the genus

Source: Butterflies of Toronto: A Guide to their Remarkable World. City of Toronto Biodiversity Series. City of Toronto, 2011.

Caterpillar Plants (Host Plants) Common Name Scientific Name Species whose caterpillars use this plant speckled alder Alnus incana Harvester (woolly aphids) hog peanut Amphicarpaea bracteata Silver-spotted Skipper, Northern Cloudywing pearly everlasting Anaphalis margaritacea American Lady bluestem Andropogon spp. Leonards Skipper, Crossline Skipper, Delaware Skipper, Common Wood-Nymph dill Anethum graveolens Black Swallowtail burdock Arctium spp. Painted Lady Dutchmans pipe Aristolochia durior Pipevine Swallowtail milkweed Asclepias spp. Monarch birch Betula spp. Compton Tortoiseshell thistle Carduus spp., Cirsium spp. Painted Lady sedge Carex spp. Broad-winged Skipper, Black Dash, Dion Skipper, Dun Skipper, Eyed Brown New Jersey tea Ceanothus americanus Mottled Duskywing, Summer Azure hackberry Celtis occidentalis American Snout, Tawny Emperor, Question Mark turtlehead Chelone spp. Baltimore Checkerspot dogwood Cornus spp. Spring Azure, Summer Azure crown vetch Coronilla varia Wild Indigo Duskywing native hawthorn Crataegus spp. Striped Hairstreak, White Admiral/Red-spotted Purple Queen Annes lace Daucus carota Black Swallowtail tick trefoil Desmodium spp. Northern Cloudywing, Eastern Tailed-Blue fennel Foeniculum vulgare Black Swallowtail




Common Name Scientific Name Species whose caterpillars use this plant gerardia Gerardia spp. Common Buckeye wild sunflower Helianthus spp. Silvery Checkerspot butter-and-eggs Linaria vulgaris Common Buckeye wild lupine Lupinus perennis Wild Indigo Duskywing, Karner Blue apple Malus spp. White Admiral/Red-spotted Purple alfalfa Medicago sativa Clouded Sulphur, Orange Sulphur, Eastern Tailed-Blue sweet-clover Melilotus spp. Orange Sulphur, Summer Azure, Silvery Blue panic grass Panicum spp. Tawny-edged Skipper, Northern Broken-Dash, Hobomok Skipper parsley Petroselinum crispum Black Swallowtail timothy Phleum pratense European Skipper, Long Dash ninebark Physocarpus opulifolius Spring Azure, Summer Azure English plantain Plantago lanceolata Common Buckeye native pine Pinus spp. Eastern Pine Elfin bluegrass Poa pratensis Long Dash, Hobomok Skipper, Common Ringlet, Little Wood-Satyr native poplar Populus spp. Dreamy Duskywing, Canadian Tiger Swallowtail, Red-spotted Purple/White Admiral, Viceroy cherry/plum Prunus spp. Canadian Tiger Swallowtail, Eastern Tiger Swallowtail, Coral Hairstreak, Striped Hairstreak, Spring Azure, Cherry Gall Azure, Red-spotted Purple/White Admiral hoptree Ptelea trifoliata Giant Swallowtail oak Quercus spp. Juvenals Duskywing, Edwards Hairstreak, Banded Hairstreak black locust Robinia pseudoacacia Silver-spotted Skipper curled dock Rumex crispus American Copper, Bronze Copper sheep sorrel Rumex acetosella American Copper rue Ruta graveolens Black Swallowtail, Giant Swallowtail willow Salix spp. Dreamy Duskywing, Red-spotted Purple/White Admiral, Viceroy, Compton Tortoiseshell, Mourning Cloak, Green Comma sassafras Sassafras albidum Spicebush Swallowtail wild mustard Sinapis arvensis spp. Mustard White aster Symphyotrichum spp. Pearl Crescent, Northern Crescent clover Trifolium spp. Clouded Sulphur, Eastern Tailed-Blue elm Ulmus spp. Mourning Cloak, Question Mark, Eastern Comma nettle Urtica spp., Laportea spp. Red Admiral, Milberts Tortoiseshell, Question Mark, Eastern Comma viburnum Viburnum spp. Spring Azure, Summer Azure vetch Vicia spp. Clouded Sulphur, Orange Sulphur, Eastern Tailed-Blue, Silvery Blue violet Viola spp. Variegated Fritillary, Silver-bordered Fritillary, Meadow Fritillary, Great Spangled Fritillary pansy Viola wittrockiana Variegated Fritillary prickly ash Zanthoxylum americanum Giant Swallowtail


TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING

Nectar Plants

SPRING FLOWERING (March early June) Common Name Scientific Name serviceberry Amelanchier spp. dogwood Cornus spp. hawthorn Crataegus spp. fleabane Erigeron spp. wild strawberry Fragaria virginiana dames rocket Hesperis matronalis apple Malus spp. ninebark Physocarpus opulifolius buttercup Ranunculus spp. blackberry/raspberry Rubus spp. elderberry Sambucus spp. cup plant Silphium perfoliatum lilac Syringa spp. dandelion Taraxacum officinale coltsfoot Tussilago farfara thyme Thymus spp. viburnum Viburnum spp. violet Viola spp.

catnip Nepeta cataria phlox Phlox spp. cinquefoil Potentilla spp. buttercup Ranunculus spp. prairie coneflower Ratibida spp. staghorn sumac Rhus typhina black-eyed Susan Rudbeckia hirta tall coneflower Rudbeckia laciniata brown-eyed coneflower Rudbeckia triloba rue Ruta graveolens salvia Salvia spp. scabiosa Scabiosa spp. clover Trifolium spp. heliotrope Valeriana officinalis vervain Verbena spp. ironweed Vernonia spp. zinnia Zinnia spp.

SUMMER FLOWERING (June August) Common Name Scientific Name chives Allium schoenoprasum dogbane Apocynum spp. milkweed Asclepias spp. butterfly bush Buddleja davidii virgins bower Clematis virginiana coreopsis Coreopsis spp. purple coneflower Echinacea spp. Joe-Pye weed Eupatorium purpureum heliotrope Heliotropium spp. lantana Lantana spp. blazing star Liatris spp. purple loosestrife Lythrum salicana alfalfa Medicago sativa sweet-clover Melilotus spp. mint Mentha spp. bee-balm Monarda didyma wild bergamot Monarda fistulosa

FALL FLOWERING (September October) Common Name Scientific Name spotted knapweed Centaurea maculosa boneset Eupatorium perfoliatum showy stonecrop Sedum spectabile goldenrod Solidago spp. aster Symphyotrichum spp.

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