Using Native Plant Communities as a
Template for Green Roof Design
Doug Daley, P.E.
Environmental Resources Engineering
SUNY College of Environmental Science and Forestry
Syracuse, NY
Annual Meeting of the American Ecological Engineering
Society
June7-9, 2012
Summary
• Native plant communities are used as the basis
for a Proof-of-Concept design approach
• Rooftop growing conditions at SUNY ESF Gateway
Building will emulate dune and alvar communities
found along the eastern shore of Lake Ontario
• Rooftop system will meet hydrologic performance
requirements, support efforts to conserve unique
ecological resources, and educate ESF’s broad
community, including parents, students, Board,
SUNY, municipal officials, designers,…
Green Roof Design in NY
• NYS Stormwater Management Design Manual:
Green Roof (Chapters 4/5)
• Runoff reduction by storage and ET
Design Components - Functional
• Structural support
• Waterproof barrier
• Drainage layer (soil) supports vegetation, no
clay, porosity > 15%
• Geosynthetic filter fabrics to prevent clogging
• Plants with tolerance for regional climate,
harsh rooftop conditions and shallow rooting
depth (e.g. alpine, arid)
Role of Vegetation
• Evapotranspiration
• Vegetation on extensive roof captures about
10% of storm event (Michigan State,
VanWoert, et al, 2005, JEQ, 34(3): 1036-1044)
• Medium captures about 50%
• Other values
– Aesthetic
– Habitat
– Conservation
Green Roof Classes
• Intensive
– Wide variety of plant species, including shrubs and
trees, greater diversity of choice
– Deeper substrate >4” to 6”
– Park-like and accessible
• Extensive
– Shallow soil (<=4”)
– Herbs, mosses, grasses, sedums (NYSDEC)
– “Low” maintenance – 2 visits/year to remove
“invasives”
• Native vegetation is recommended (NYSDEC)
SUNY ESF Gateway Building
Great Lakes Sand Dunes
• Growing
conditions
include extreme
temperatures,
strong winds,
shifting sands
American beachgrass, Ammophila breviligulata
http://www.seagrant.sunysb.edu/glhabitat/PDFS/ELODWAFactSheetDunePlants.pdf
Endangered plant species found there:
• Champlain beachgrass (Ammophila
breviligulata),
• rough avens (Geum laciniatum),
• woodland bluegrass (Poa sylvestris),
• marsh horsetail (Equisetum palustre),
• large twayblade (Liparis liliifolia),
• livid sedge (Carex livida),
• giant pine drops (Pterospora andromedea)
• sand dune willow (Salix cordata).
Alvar Barrens
• Prairie-like barrens
– Flat, thin- to no-soiled, rocky (limestone bedrock)
– Grasslands, limestone woodlands, cedar forests,
pavement barrens
– Adapted to extreme conditions:
• Shallow soil, regular spring flooding, summer drought
• Local Nature Conservancy efforts at Chaumont
Barrens Preserve, Jefferson County
– Extend through Michigan
http://www.epa.gov/ecopage/shore/lakeont.html
Alvar Pavement Barrens
Plenty of Options for Color and Texture
Selected Alvar Species
Agropyron trachycaulum – slender
wheatgrass
Aquilegia canadensis – wild columbine
Artemisa campestris var. caudata – tall
wormwood
Aster ciliolatus – aster
Bromus kalmii – brome grass
Carex eburnea – ebony sedge
Carex granularis – sedge
Carex vulpinoidea – brown fox sedge
Danthonia spicata – poverty grass
Deschampsia cespitosa – tufted
hairgrass
Fragaria virginiana –wild strawberry
Geum triflorum – prairie smoke
Juniperus communis – common juniper
Muhlenbergia glomerata – spike or marsh
muhly
Oligoneuron album – upland white aster
Penstemon hirsutus - hairy beardtongue
Rosa blanda – meadow rose
Saxifraga virginiensis – early saxifrage
Solidago hispida – goldenrod
Solidago nemoralis – gray goldenrod
Sporobolus heterolepis – northern prairie
dropseed
Zigadenus elegans var. glaucus – white
camas
Zizia aurea – golden alexanders
Green PRoof
• Original design – SUNY CF
– Thin soil, sedums
• Uprising
– Original thought?
– Creative design?
– World-class environmental science and design
programs?
• Team of ecologists, LA, engineer
Green PRoof of Concept – Day 13
8” Bed
3” Bed
Concept – Day 34 (July 19)
Concept – Day 64 (August 18)
Dune Willow, Salix cordata (3 months)
Tall wormwood, Artemisa
campestris var. caudata (Day 10134)
Rapid coverage, great survival
Sand cherry, Prunus pumila var.
depressa
Sand cherry was pruned to reduce competition, and provided great
color and cover
Color/Texture
June 6, 2012 (Year 3)
ESF Gateway Building – Green Roof
Section
Mirafi G4
ESF Gateway Bldg – Dune Profile
MiraDrain G4 Drainage Composite
•
•
•
•
•
Filter fabric
Moisture retention mat
Drainage mat
Protection Fabric
Storage Capacity = 0.32” rain (7.97 L/m2 )(1.63
lb water/SF)
• Flow rate = 75 gpm/SF
Green Roof Runoff Reduction
• Water Quality
volume (WQv) =
678 CF
• Storage Volume=
739 + 0 + 132 + 0 =
871 cf
• WQv<Storage
P (in) = 90% Rainfall Event Number
(See Figure 4.1) = 0.9
I = Impervious Cover = 100 Percent
Rv = 0.95
A = site area = 9500 SF
Minimum Rv = 0.2 if WQv > RRv
( P )( Rv )( A)
WQv 
12
Rv  0.05  0.009( I )
Vtotal  Vsoil  Vdrainlayer  Vdrainmat  Vponding
Dune and Alvar Plantings
Sand
Dune
Willow
Salix
cordata
American
Beachgrass
Canada Wild Rye
Wavy Hairgrass
Field Wormwood
Eastern Sand Cherry
Monitoring
•
•
•
•
Soil temperature, moisture content
Survival, growth and cover
Pioneers
Precipitation, runoff
Design and Management Issues
• Designer resistance
– Innovative? Need proof of concept
– Faith?
• Plant propagation
– Sedums are widely available
• Cost
– Additional soil, unusual plants and increased
structural loads
• Management
– is it a garden, or a native system?
Summary
• Native plant communities are used as the basis
for a Proof-of-Concept design approach
• Rooftop growing conditions at SUNY ESF Gateway
Building will emulate dune and alvar communities
found along the eastern shore of Lake Ontario
• Rooftop system will meet hydrologic performance
requirements, support efforts to conserve unique
ecological resources, and educate ESF’s broad
community, including parents, students, Board,
SUNY, municipal officials, designers,…
Acknowledgments
• Co-Authors/Investigators/Photographers
(SUNY ESF)
– Tim Toland
– Don Leopold
– Terry Ettinger
– James Johnson
• SUNY Construction Fund
• NY Economic Development
• Illustrations: Sea Grant New York