Knowledge - Greenroofing Info Sheet.indd

Transcription

BritishFlora
Planting the seeds for a greener tomorrow
BIODIVERSE GREENROOF INFORMATION
BritishFloraare
arespecialist
specialistgrowers
growersand
andsuppliers
suppliersofofUKUKNative
Nativeand
andlocal
localprovenance
provenancewildflowers
wildflowers
BritishFlora
andseed.
seed.We
Wesupport
supportthe
thegreenroofing
greenroofingindustry
industryininproviding
providingexpert
expertecological
ecologicaland
andhorticultural
horticultural
and
adviceononspecies
speciesselection,
selection,biodiversity
biodiversityenhancement,
enhancement,maintenance
maintenanceand
andestablishment
establishmentofofplants
plants
advice
greenroofenvironment.
environment.We
Wehave
havea ateam
teamofofskilled
skilledlandscapers
landscapersthat
thatcan
caninstall
installthe
thevegetation
vegetation
inina agreenroof
biodiversegreenroofs
greenroofsincluding
includingplug
plugplanting,
planting,seeding,
seeding,wildflower
wildflowerand
andsedum
sedumblankets
blanketsand
and
ononbiodiverse
other
substrate
and
wildlife
features.
We
can
also
provide
a
maintenance
and
monitoring
service
other substrate and wildlife features. We can also provide a maintenance and monitoring service
integraltotothe
theestablishment
establishmentofofa asuccessful
successfulgreenroof.
greenroof.
integral
BritishFloraare
areaffiliate
affiliatemembers
membersofofBritish
BritishAssociation
AssociationofofLandscape
LandscapeIndustries
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andadhere
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BritishFlora
theflora
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ecologistis isa aFull
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of
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Member of the Institute of Ecology and Environmental Management (IEEM) and can advise onon
enhancingbiodiversity
biodiversityononyour
yourgreenroof
greenroofand
andattaining
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landscapeand
andecology
ecologycredits
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enhancing
SustainableHomes
Homes(CSH)
(CSH)and
andBREEAM.
BREEAM. The
Thefollowing
followingInformation
Informationnote
noteis isa abrief
briefoutline
outlineofof
forforSustainable
greenroofs
focusingonon
thevegetation
vegetationsystem.
system.
greenroofs
focusing
the
Benefits of Greenroofs
x
x
x
x
x
x
Creates Ecological Habitats and Encourages Biodiversity
Water Retention and Harvesting & Improved water quality
Improves Air Quality
Reduces Urban Heat Island Effect
Creates Amenity Space & Wellbeing
Financial Benefits- Aid to Planning Consent (BREEAM, CSH), Reduced Building Running Costs
Grange Farm, Grange Road, Widmer End, Bucks, HP15 6AE
T. 01494 718203 F. 01494 718989
www.britishflora.co.uk
The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ
info@britishflora.co.uk
T: 01684 212027 F: 01684 578424
Registered in Cardiff No: 4376669 VAT No: 727 5996 79
Registration No. 8730825 VAT No. 178 1624 88
Registered Address: The Bakery, Old Vicarage, Hanley Castle, Worcestershire WR8 0BJ
BritishFlora
Types of Greenroof;
There are a number of different types of greenroofs and terms used to describe them including;
Sedum roof, Extensive, Semi-intensive and Intensive, which are defined by substrate depth and
the plant communities that can establish on these mediums. Intensive greenroofs are also known
as rooftop gardens and can include anything from trees and shrubs to swimming pools and
allotments. The ‘biodiverse’ or extensive roof is a shallow light weight system that can support a
diverse assemblage of native wildflowers to create ecological habitats for wildlife.
BritishFlora specialize in specifying and installing the vegetation layer for extensive/biodiverse and
semi-intensive greenroofs. Weights and depths of substrates can vary and a suitably qualified
greenroof designer and architect will need to be consulted on weight bearing loads of different
roof designs. The Table below provides a guide to weight and depth of substrates in different
greenroofing systems.
Table.1. Comparison of different greenroof systems
Sedum Roof
Extensive/’Biodiverse’ Semi intensive
Intensive/Rooftop
Garden
Vegetation
Sedum spp. and
Wildflowers & Grasses
Grasses, Herbs &
Herbs, Shrubs,
mosses
usually UK Native
Shrubs
Trees &
vegetable
plants specified
growing
Depth/Type of
20-60mm,
60-200mm, recycled
120-250mm
150-400mm.
Substrate
recycled crush
crush brick, 10%
Crushed brick,
Light weight
brick, 10%
organic content
10% organic
compost
content
organic content
Substrate
10-60kg/m2
60-150 kg/m2
120-200 kg/m2
180-500 kg/m2
Low
Periodic
Periodic
High
Weight
(saturated)
Maintenance
Greenroof Layer system
Terrestrial vegetation requires adequate water,
nutrients, drainage and air circulating around
the roots to survive and this is recreated in the
greenroofing layering system:
1. Seeds, plants or vegetation mat
BritishFlora
2.
3.
4.
5.
6.
Light weight substrate- porous and free draining
Filter sheet to prevent blockage of drainage board
Drainage and reservoir layer
Moisture retention blanket
Waterproof and root membrane
Greenroof Design and Planning
Fig.1. Greenroof Layer System
A greenroof specialist and architect must be involved
in designing a greenroof to calculate weight loading capacities and the appropriate greenroof
layering system. BritishFlora works closely with greenroof designers to provide expert horticultural
and ecological advice on native species planting, substrates and maintenance. An assessment
of the prevailing conditions expected on the greenroof must be undertaken such as the
prevailing wind direction, wind strength and shading to determine the vegetation suitable for the
roof. There are seasonal constraints when establishing vegetation on a greenroof and therefore
adequate planning is essential (see section on establishing vegetation below).
UK Native Plant species for a ‘biodiverse’ roof
The vegetation that will establish well in the dry, shallow soils and low nutrient environment on an
extensive green roof are wildflowers and grasses that naturally occur in these harsh environments
in the UK. These are the wildflowers, grasses and sedges of chalk/limestone, sandy soils and
coastal grasslands, which are increasingly under threat in our natural habitats. The table at the
end of this document is a recommended list of UK Native plants that are proven to establish well
on extensive and semi-intensive greenroofs. The plant mix is biodiverse and can be adapted to
encourage certain wildlife e.g. leguminaceae plant species such as red clover and kidney vetch
provide valuable feeding for certain long-tongue bee species. The seed heads of yellow-wort or
campion species provide overwintering for invertebrates and therefore provide valuable foraging
potential for black redstart Biodiversity Action Plan species.
Establishing vegetation on a greenroof
Seeding
Seeding is the least expensive way to vegetate a greenroof and is particularly recommended for
large areas over 1500m2. There is a wider choice of species available from seed and the
installation is relatively straightforward involving hand broadcasting or a mechanical spreader
over larger areas. The roof can take up to 2 years before it looks established when using seed
and most perennials will not flower until the second growing season. Substrates specifically
designed for seeding are available that have a smaller particle size and higher organic content
and depths should range between 50-150mm depending on the seed mix.
Autumn sowing in August/September, depending on prevailing weather conditions, is
recommended to ensure that seedlings will germinate in favorable conditions rather than be
exposed to potentially hot and dry conditions of spring and summer. Irrigation of roof after
seeding and lightly covering the seed can extend the potential sowing period. BritishFlora
technical team can advise on the timing, seeding rates, substrates, and other materials needed
to be added to the seed mix to ensure even and effective establishment of your green roof.
T: 01684 212027 F: 01684 578424
BritishFlora
Plug planting
Plug planting is an effective way of quickly establishing a greenroof and a wide range of species
suitable for greenroofing are available in plug plants. Extensive light weight substrates between
80-150mm are suitable for wildflower plug plants, with some plants requiring deeper substrates
than others (refer to plant species table at the end of the document). Ideally plug plants should
be planted at the beginning of the growing season in March or April to allow a full growing
season for the plants to establish. BritishFlora technical team can advise on planting densities,
suitable substrates and additional growing materials than will ensure establishment of plug plants.
Fig.3. 27cc
greenroofing
wildflower
plug
used
in
Fig.2. Planting wildflower plugs into greenroof substrate
Sedum and wildflower blankets or pre-established systems
A pre-established sedum or wildflower turf provides an instant green blanket effect and has the
wow factor, especially when wildflowers are incorporated. This is the most expensive solution
over larger areas and species mixes are limited to those grown on the blanket unless bespoke
versions are grown to order. The weight of a wildflower blanket ranges from 35-44kg per m2
saturated weight versus 2-5kg per m2 for wildflower plugs so additional weight bearing needs to
be considered. Daily irrigation of wildflower blankets during the establishment period is required
and during subsequent extended dry spells to keep these blankets looking lush and green.
Additional species can be added to a wildflower/sedum blanket by plug planting or over
seeding into the blanket.
Fig.4. Wildflower blanket
BritishFlora
Diverse substrate materials and depths
A biodiverse roof should include a variety of substrate types and depths to increase the mosaic of
habitat types, which in turn will encourage biodiversity and establishment of different plant
communities. Ideally the extensive substrate depth should range between 50mm and 150mm to
allow for different plant Fig.4.
communities
to blanket
thrive, for example sedum will establish on the shallow
Wildflower
substrates and taller perennial such as field scabious will thrive on the deeper substrates up to
150mm.
Diverse
substrate
materials
and depths
Biodiverse
roofs aim
to recreate
brownfield sites, including habitat mosaics of bare ground,
diverse vegetation and substrate types and low nutrient soil to allow less competitive wildflowers
A
roofhabitats
should include
a variety
of substrate
types and depths
to and
increase
the mosaic
of
tobiodiverse
thrive. These
provide
ideal foraging
for invertebrates,
birds
mammal
species.
habitat
types, which
turn and
will encourage
and establishment
of from
different
plant
Sands mounds,
gravel,instone
wood piles biodiversity
provide important
wildlife refuges
the harsh
communities.
Ideally
the
extensive
substrate
depth
should
range
between
50mm
and
150mm
to
environment on a green roof and burrowing habitat for invertebrate species such as mining bees,
allow
for different
plant dwelling
communities
to thrive,
for example
sedumbe
will
establish on
the loading
shallow
sand wasps
and ground
beetles.
Substrate
features should
considered
where
substrates
and
taller
perennial
such
as
field
scabious
will
thrive
on
the
deeper
substrates
up to
capacity allows on the building (discuss with architect/engineer).
150mm.
Where wind erosion is a problem heavier substrates can be used effectively to weigh down the
Biodiverse
roofs aimand
to allow
recreate
brownfield
sites,
habitat mosaics
of bare
ground,
extensive substrate
plants
to establish
by including
creating sheltered
areas behind
stone
piles.
diverse
vegetation
and
substrate
types
and
low
nutrient
soil
to
allow
less
competitive
wildflowers
See Fig.5. below as an example of wind scouring remediation solution.
to thrive. These habitats provide ideal foraging for invertebrates, birds and mammal species.
Sands mounds, gravel, stone and wood piles provide important wildlife refuges from the harsh
environment on a green roof and burrowing habitat for invertebrate species such as mining bees,
sand wasps and ground dwelling beetles. Substrate features should be considered where loading
capacity allows on the building (discuss with architect/engineer).
Where wind erosion is a problem heavier substrates can be used effectively to weigh down the
extensive substrate and allow plants to establish by creating sheltered areas behind stone piles.
See Fig.5. below as an example of wind scouring remediation solution.
Fig.5. Sand mounds and rockery areas on a greenroof
Fig.5. Sand mounds and rockery areas on a greenroof
T: 01684 212027 F: 01684 578424
BritishFlora
Maintenance
Contrary to popular belief a biodiverse roof does require maintenance, especially during the
establishment period (up to 3 months after planting). Irrigation is particularly important in the first
10 weeks and on roofs over 500m2 an automated sprinkler of leaky pipe system should be
considered to maintain plant health. For plug plants irrigation is required every 4 days to once a
week during the establishment period but wildflower blankets require daily irrigation during dry
spells. Greenroofs are very nutrient poor environments and therefore slow release fertilizer should
be applied at the beginning of the growing season to help plants establish.
Additional maintenance tasks include removal of unwanted weeds and dead heading of
perennials in the spring to allow for new growth. Old seeds heads should be left to overwinter to
provide foraging potential for birds and overwintering sites for invertebrates. Cutting of wildflower
turf and removal of this vegetation is required annually.
BritishFlora can provide a full
maintenance service to ensure your greenroof performs to expectations.
Further reading
Dunnett, N. P. & Kingsbury, N. (2008) Planting Green Roofs and Living Walls, 2nd edition. Timber Press,
Portland, Oregon.
Dunnett, N. P. & Kingsbury, N. (2004) Green Roofs and Living Walls. Timber Press, Portland, Oregon.
GRO Greenroof Code (2011). The Greenroof Code of Best Practice for the UK 2011. The Greenroof
Organisation (GRO) Technical Advisory Group.
Gedge, D., Dunnett, N. & Grant, G. & Jones, R. (2006) Living Roofs. English Nature, Peterborough
Snodgrass E, Snodgrass L (2006). Greenroof Plants. Timber Press, Portland, Oregon.
T: 01684 212027 F: 01684 578424
BritishFlora
Table.2. Biodiverse UK Native Plant Mix for Greenroofing
Plant Name
Biting Stonecrop –
Sedum acre
Comments
Succulent plant suitable for
very dry shallow substrates.
Yellow flowers.
Can grow in very shallow
substrate
10-100mm.
Table.2. Biodiverse
UK
Native
Plant
Mix
for
Greenroofing
Buck's Horn Plantain Suitable for windy and
Plantago coronopus
coastal sites
Comments
Plant Name
Substrate depth of 50100mm.
heads
SucculentSeed
plant
suitable for
Centaury –
suitable
foraging
birds
very dryfor
shallow
substrates.
Centaurium erythraea
Yellow flowers.
Biting Stonecrop –
Substrate depth of 50Sedum acre
100mm. Medium height
Can grow in very shallow
perennial
substrate
10-100mm.
Clustered
bellflowerBuck's Horn Plantain Suitable for windy and
Campanula
glomerata
Plantago coronopus
coastal sites
Prostrate/creeping
Substrate depth of 50perennial.
Substrate
100mm. Seed
heads depth
of
50-100mm.
Good
Centaury –
suitable
for foraging birds
foraging
for
long
tongues
Common
Bird'sfootCentaurium erythraea
bee
species
including
trefoil –
Substrate
depth of 50bumble
bees
Lotus corniculatus
100mm. Medium height
Medium height perennial.
perennial
Common
Cat’s
Ear
Substrate
depth of 50Clustered
bellflower100mm.
Hypochaeris
radicata
Campanula glomerata
100-150mm
Prostrate/creeping deeper
substrate
required,
perennial. depth
Substrate
depth
Common Knapweedmedium
tall
perennial
of
50-100mm.
Good
Centaurea nigra
foraging
for
long
tongues
Common
Bird'sfootSubstrate
depth including
of 50bee
species
trefoil –
100mm.
Annual
from
seed,
bumble bees
Lotus corniculatus
colour in the first year
Common
Poppy
Common
Cat’s
Ear
Substrate
depth of 50Papaver rhoeas
100mm.
Hypochaeris radicata
100-150mm
deeper
substrate depth required,
Common Knapweedmedium tall perennial
Centaurea nigra
Substrate depth of 50100mm. Annual from seed,
colour in the first year
Common
Poppy
Papaver rhoeas
T: 01684 212027 F: 01684 578424
BritishFlora
Comments
Comments
Medium
Medium perennial,
perennial, blush
blush red
red
throughout
summer
throughout
summer
Substrate
Substrate depth
depth of
of 5050100mm.
100mm.
Plant
Plant Name
Name
Common
Common Sorrel
Sorrel ––
Rumex
Rumex acetosa
acetosa
Substrate
Substrate depth
depth of
of 5050100mm.
100mm. Annual
Annual to
to grow
grow
from
from seed
seed provides
provides colour
colour in
in
first
growing
season
first growing season
Medium
Medium height
height perennial.
perennial.
Substrate
depth
Substrate depth of
of 5050100mm.
100mm. Spring
Spring flowering
flowering
CornflowerCornflowerCentaurea
Centaurea cyanus
cyanus
Cowslip
Cowslip -- Primula
Primula veris
veris
Deeper
Deeper
150mm
150mm
Field
Field Scabious
Scabious ––
Knautia
Knautia arvensis
arvensis
100100-
Sedge
Sedge of
of dry
dry grasslands.
grasslands.
Substrate
Substrate depth
depth of
of 5050100mm
100mm
Glaucous
Glaucous sedgesedgeCarex
Carex flacca
flacca
Herb-Robert
-Herb-Robert
Geranium
robertianum
Geranium robertianum
Kidney
Kidney vetchvetchAnthyllis
Anthyllis vulneraria
vulneraria
Lady’s
Bedstraw
Lady’s
Bedstraw
Galium
verum
Galium verum
substrate
substrate
Substrate
Substrate depth
depth of
of 5050100mm.
100mm. Suitable
Suitable for
for shaded
shaded
and
and exposed
exposed areas
areas
Clump
Clump forming
forming prolific
prolific self
self
seeder
seeder suitable
suitable for
for all
all
biodiverse
biodiverse roofs.
roofs. Substrate
Substrate
depth
of
50-100mm.
depth of 50-100mm. Nectar
Nectar
sources
sources bees
bees and
and butterflies
butterflies
(small
(small blue)
blue)
Substrate
Substrate depth
depth of
of 50-100m,
50-100m,
medium
to
tall
perennial,
medium to tall perennial,
slow
slow growing
growing
-The Bakery, Old vicarage, Hanley Castle, Worcestershire WR8 0BJ
T: 01684 212027 F: 01684 578424
BritishFlora
Comments
Tall perennial,
quick grower
Plant Name
Ox-eye Daisy –
Leucanthemum
vulgare
Perforate St. John’swort –
Hypericum perforatum
Substrate depth of 50100mm. Seed heads good
foraging resource for bird
species
Low
growing
perennial,
nectar source for long
tongued
bee
species
including bumble bees
Red Clover –
Trifolium pretense
Ribwort Plantain –
Plantago lanceolata
Substrate depth of 50100mm,
clump
forming
perennial. Very good nectar
source and foraging
Rock Rose –
Helianthemum
nummularium
Rough
Hawkbit
Leontodon hispidus
-
Very drought
tolerant.
Salad Burnet –
Sanguisorba minor
Substrate depth of 50100mm. Very good nectar
source for inverts.
Small
Scabious
Scabiosa columbaria
T: 01684 212027 F: 01684 578424
BritishFlora
Plant Name
Comments
Suitable for windy sites and
those near the sea. 50100mm substrate
Thrift- Armeria maritima
spp maritima
Thyme –
Thymus polytrichus
Mat
forming
aromatic
perennial. Good for high
foot traffic areas and
shallow substrates under
50mm
Tall
biennial,
deeper
substrates
100-150mm.
Good nectar resource for
inverts,
good
potential
foraging habitat
Viper's Bugloss –
Echium vulgare
White Campion - Silene
latifolia/alba
Resource for
foraging moths and night
flying inverts and therefore
attracts bats.
Succulent plant suitable for
very dry shallow substrates.
White flowers.
White Stonecrop –
Sedum alba
Wild Basil –
Clinopodium vulgare
Wild Carrot –
Daucus carota
Wild marjoram –
Origanum vulgare
Aromatic
small
perennial. Attracts foraging
moths and therefore bats
Medium height perennial,
deeper
substrates
100150mm.
Substrate depth of 50100mm. Attracts foraging
moths and therefore bats
T: 01684 212027 F: 01684 578424
BritishFlora
Plant Name
Wild Pansy/Heartsease
- Viola tricolor
Comments
Small perennial, requires
substrate depth of 50100mm. Extended flowering
period
Substrate
100mm
depth
of
50-
YarrowAchillea millefolium
Yellow toadflax –
Linaria vulgaris
Yellow-wortBlackstonia perfoliata
Substrate depth of 50100mm. Suitable foraging
for black redstarts,
invertebrates overwinter in
seed heads
T: 01684 212027 F: 01684 578424

Knowledge - Greenroofing Info Sheet.indd

Transcription

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