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Insects and Green Walls
Caroline Chiquet, John Dover, Paul Mitchell, Dave Skingsley, Roger Dennis
The Green Wall Centre, Staffordshire University, Stoke-on-Trent ST4 2DF, UK.
http://www.staffs.ac.uk/research/greenwall/
Types of Green Wall
CONTEXT
Very little had been published on insects on Green walls – especially in English
None on living walls
But insects are important – ecosystem services
In urban areas – may be the only habitat available or exploited
Mean abundance of pollinating insects
visiting ivy flowers (on hedges) in 18 x 0.5 m2
quadrats
(Jacobs et al. 2010).A problem?
River Walls and Embankments
River walls along the Thames estuary foreshore (Attrill et al. 1999)Hoggart et al. (2012) 15 vertical wall sites along Thames in London.
© John Dover
Not all insects on green walls have the same lifestyle
Hagedoorn & Zucchi (1989)
Phytophages
(Herbivores)© John Dover
Saprophages
(Detritus feeders)
Jokey images of bottom feeders removed
Saproxylic
(Dead wood eaters)
Image of Beaver eating tree removed to protect the innocent
Predators
(Predators)
Picture of scary Dinosaur removed for public safety
Parasites
(Parasites)
Horrible pictures of parasites removed for reasons of good taste
This study
Insects surveyed on:
•Green Façades•Living Walls•Green Screens
Green Façades
29 Green Façades compared with Bare Walls
Green Façades - Ivy
Species used:
H. helixH. colchicaH. iberica© John Dover
Green Façades – Boston Ivy
Parthenocissus tricuspidata
© John Dover
Green Façades – Virginia Creeper
Parthenocissus quinquefolia
© John Dover
Green Façades – Pyracanthus
© John Dover© John Dover
Green Façades – Wisteria
© John Dover
Green Façades – Jasmine
m2
© John Dover
© John Dover
Sampled• 29 Façades and bare walls• Summer and autumn• 3 times/season• 2-6 sites a day• Deciduous and evergreen• Single or multiple species
Vortis© John Dover
Locations: Newcastle-under-Lyme and Stoke-on-Trent
Compared
Total insect abundance and richness (all insects)
Abundance and richness of the Orders:• Coleoptera (beetles)• Diptera (flies)• Hemiptera (bugs)• Hymenoptera (bees and wasps)
Total Abundance
Bare walls: 124
Green Facades: 6404
Mostly:• Hymenoptera 1599• Diptera 1558 • Hemiptera 1324
0
200
400
600
800
1000
1200
Booklice Parasiticwasps
Leaf hopper Aphids Gall midges Parasiticwasps
Tota
l ab
un
dan
ceGreen Façades – most abundant families
Most numerous ‘Family’ members
Total Richness – Green façades
0
5
10
15
20
25
30
35
40
Overall Beetles Flies Bugs Bees. Etc
Mea
n n
um
ber
of
spec
ies
±SE Façades: 208 species
Bare walls: 2 species
0
6
12
Coleoptera Diptera Hemiptera Hymenoptera
mean insect abundance
Beetles Flies Bugs Bees & Wasps
12
6
Mea
n in
sect
ab
un
dan
ceSummer Autumn
0
2.5
5
Coleoptera Diptera Hemiptera Hymenoptera
mean insect richness
Beetles Flies Bugs Bees & Wasps
5.0
2.5
Mea
n in
sect
ric
hn
ess
Summer Autumn
0
10
20
30
40
50
Evergreen Deciduous
Abundance
0
2
4
6
8
10
12
14
Evergreen Deciduous
Richness
Deciduous & Evergreen foliage (overall)
0
6
12
Coleoptera Diptera Hemiptera Hymenoptera
mean insect abundance
12
6
Beetles Flies Bugs Bees & wasps
Mea
n a
bu
nd
ance
EvergreenDeciduous
Deciduous & Evergreen abundance
0
2
4
Coleoptera Diptera Hemiptera Hymenoptera
mean insect richness
4
2
Beetles Flies Bugs Bees & wasps
Mea
n r
ich
nes
s
EvergreenDeciduous
Deciduous & Evergreen richness
0
60
120
summer autumn
mean insect abundance
diverse species (other than Hedera spp.)
diverse species (Hedera spp.)
single species (not Hedera sp.)
single species (Hedera sp.)
Summer Autumn
120
60
Mea
n a
bu
nd
ance
Polyculture/Monoculture
0
10
20
mean insect richness
diverse species (other than Hedera spp.)
diverse species (Hedera spp.)
single species (not Hedera sp.)
single species (Hedera sp.)
Summer Autumn
20
10
Mea
n r
ich
nes
s
Polyculture/Monoculture
Living Walls
22 Living Walls from 6 manufacturers
Located: Greater London (13) and Birmingham (9)
+ 4 ‘Green Screens’ : Stoke-on-Trent (2), London (2)
© John Dover
ANS
Plastic modules, open vertically and slightly angled to hold growing media
© John Dover
Treebox
Easiwall system: Plastic modules, horizontally open at the top, angled front
http://www.alexandrafroggatt.com/treebox/
For pictures of this system see:
Biotecture
Grodan rockwool units with polypropylene surround and front
© John Dover
Mobilane
Hydrophobic rockwoolunits with embedded growing medium
© John Dover
© John Dover
Wallflore system*
http://wallflore.de/projecten/jean-paul-viguier.html
Rockwool units with geo-textile in front
* Supplied by Grange Construction & Roofing Company Ltd.
For pictures of this system see:
Treebox
www.alexandrafroggatt.com
Bin Fen system: plastic pots attached to a mesh
For pictures of this system see:
Mobilane Green Screens
© John Dover
© John Dover
Birmingham
Greater London
Sampling
• 22 living walls, 4 green screens• Sampled 4 times each• July to September 2012
• 2 days/session in London, 1 day in Birmingham
© John Dover
(i) Birmingham and London(ii) green wall systems (6 different living wall
systems and green screens) (iii) plant density and the plant richness (iv) vegetation surface area (v) aspect (vi) LW age(vii) pedestrian and vehicle traffic volumes
Compared
Results
1399 insects
9 Orders61 families 137 species
Diptera (533)Hemiptera (451) Hymenoptera (217)
0
5
10
15
20
25
Overall Beetles Flies Bugs Bees &wasps
Mea
n r
ich
nes
s ±
SETotal Richness – Living Walls
137 species
0
50
100
150
200
250
300
350
Aphids Moth flies Fungus gnats non-bitingmidges
Mea
n a
bu
nd
ance
±SE
Total abundance – Living Walls
1399 insects
Most numerous ‘Family’ members
360 individuals6 orders 37 families59 species
Green screens
0
5
10
15
20
25
30
Overall Beetles Flies Bugs Bees & wasps
Mea
n a
bu
nd
ance
±SE
Green screens – Total abundance
360 individuals
Birmingham vs London
13 angled plastic units: 8 B’ham, 5 London – No differences
Different LW systems
No differences in overall richness or abundance
0
25
50
green screen plant pot horizontal plant box rockwool unit withplastic fascia
rockwool unit with feltfascia
rockwool unit angled plasticmodule
mean insect abundance
2525
Green screen
Plant pot
Horizontal planters
Rockwool + plastic front
Rockwool + felt front
Rockwool + bare front
Angled plastic unit
50
25
Mea
n a
bu
nd
ance
±SE
Living Wall system comparisons - abundance
No significant differences
0
7
14
green screen plant pot horizontal plantbox
rockwool unit withplastic fascia
rockwool unit withfelt fascia
rockwool unit angled plasticmodule
mean insect specie
s r
ichness
Green screen
Plant pot
Horizontal planters
Rockwool + plastic front
Rockwool + felt front
Rockwool + bare front
Angled plastic unit
14
7
Mea
n r
ich
ne
ss ±
SELiving Wall system comparisons - Richness
No significant differences
BUT:
Dipteran abundance was significantly greater in horizontal plant boxes than on all the other systems (with the exception of plant pot systems)
AND significantly greater in abundance in plant pot systems than in angled plastic modules
Diptera (Flies)
Dipteran richness was significantly greater in horizontal plant boxes, plant pots and green screens than in angled plastic modules
Hemipteran abundance was significantly greater in rockwool units than in all the other systems (with the exception of green screens)
AND was significantly greater in angled plastic modules than in plant pots and horizontal plant boxes
Hemipteran richness was greater in rockwoolunits than in all the other systems) and was significantly greater in angled plastic modules than in plant pots.
Hemiptera (Bugs)
Ordination using multiple correspondence analysis (MCA)
• Green façades and living walls, have an abundant and diverse insect fauna
• Diptera, Hymenoptera, and Hemiptera were the most abundant and rich insect groups found
• Some pests were present
• Nearly all Hymenoptera were wasps or parasitoids(either primary or hyperparasitoid)
• Psocoptera (book lice) – consuming decaying material
Take-home messages
Take-home cont’d
Evergreen superior to deciduous
Accessibility of media surface and decaying material may be reason for high numbers of Diptera
Hemiptera may be positively affected by high foliage density
Not possible to say whether GF, LW are better than the other – they are diffierent
Thank you for your attention!
© John Dover