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camden.gov.uk
Al Smith, Tree Manager, Camden Council
26 year analysis of street tree maintenance budgets, subsidence claims and costs
camden.gov.uk
• Where is Camden & background
• Context for carrying out the analysis
• Analysis: budgets, claim numbers & costs
• Fell & replacement programme
• ‘Small’ tree planting analysis & tree diversity
• Conclusion
Presentation content:
camden.gov.uk
Where is Camden?
camden.gov.uk
• 9,500 street trees
• 4,600 park trees
• 11,500 trees in social housing sites
• 1,500 trees in education sites
• 28,0000 trees ‘actively’ managed
• 5 to 10,000 managed trees in nature conservation sites
Numbers of Council trees in Camden:
camden.gov.uk
• Main 3 year cycle of inspection & maintenance
• Biennial ‘pollarding’ programme
• Biennial regime for epicormic (basal) growth
• Additional ‘risk’ programme of work
Street tree inspection & maintenance regimes:
camden.gov.uk
camden.gov.uk
camden.gov.uk
camden.gov.uk
camden.gov.uk
camden.gov.uk
camden.gov.uk
• Tree within the rooting influence of a property • Shrinkable London clay soil
• The trespass of tree root (re: common law)
• The tree extracting soil water from the clay over and above seasonal
movement (winter/summer)
• Action of tree roots results in damage to building
• Causation established, a claim for damage follows - £££££££££££££
Tree related subsidence damage to property:
camden.gov.uk
camden.gov.uk
• Over 70 years ago – London Plane, Limes, Elm, Maples (in the more wealthy parts of the borough)
• Over 40 years ago - National tree planting initiative in 1973 & 1974?
• Over 30 years ago - London Plane, Limes, Maples, Silver Birch, Silver Maple, Ash, Pyrus and Sorbus & Malus cultivars (large scale planting schemes borough wide)
• 10 to 20 years ago – generally replacement trees were like for like due to lack of staffing resources
• During the last 10 years – increasing emphasis on the ‘right tree for the right site’
Overview of tree planting in Camden:
camden.gov.uk
Why carry out the analysis? • ‘Justify’ tree maintenance budgets
based on ‘fact & figures’
• 2008/9, Council financial cuts of £96m (over 3yr period)
• 2014/15, further cuts of £70m (over 3yr period)
• From 2017/18, possible cuts in the region of 10m to 40m
• How can we improve Camden’s urban forest based around risk, sustainability, diversity and resilience?
camden.gov.uk
• Historic management reports: Budget information going back to 25yrs
• Data base: Confirm Arboriculture:
Maintenance budget information Tree planting information Species information
• Insurance database: LACHS database
Claim numbers & related costs going back 26yrs
Information gathered for analysis:
camden.gov.uk
Information from the Clay Research Group organisation:
camden.gov.uk
Budget profile 1988 to 2013:
£0.00
£50,000.00
£100,000.00
£150,000.00
£200,000.00
£250,000.00
£300,000.00
£350,000.00
£400,000.00
£450,000.00
£500,000.00
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
Budget
camden.gov.uk
Claim numbers 1989 to 2013:
camden.gov.uk
Claim costs 1988 to 2013:
£-
£200,000.00
£400,000.00
£600,000.00
£800,000.00
£1,000,000.00
£1,200,000.00
£1,400,000.00
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
total cost
Total cost 2010 without 1 big claim
camden.gov.uk
Results:
£-
£200,000.00
£400,000.00
£600,000.00
£800,000.00
£1,000,000.00
£1,200,000.00
£1,400,000.00
0
20
40
60
80
100
120
140
160 19
88
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
number of claims
total cost
Total cost 2010 without 1 big claim
Budget
camden.gov.uk
camden.gov.uk
Reduction in street tree claim numbers & costs:
Time Period
No. of Claims
Cost of Claims
2002-2007
503
£4.6m
2008-2013
224
£2.5m
camden.gov.uk
Updated graph with 2014 figures:
£-
£200,000.00
£400,000.00
£600,000.00
£800,000.00
£1,000,000.00
£1,200,000.00
£1,400,000.00
0
20
40
60
80
100
120
140
160 19
88
1989
19
90
1991
19
92
1993
19
94
1995
19
96
1997
19
98
1999
20
00
2001
20
02
2003
20
04
2005
20
06
2007
20
08
2009
20
10
2011
20
12
2013
20
14
2015
Incident year
Costs
Total cost 2010 without 1 big claim
Budget
camden.gov.uk
• Resources were being targeted in high claim post codes
• General maintenance regimes were up to date
• Increase the number of crown managed trees added to the 3yr cycle
• Increase numbers of trees added to the biennial pollarding programme
Analysis of street tree claim numbers by post code to ensure:
camden.gov.uk
0
50
100
150
200
250
300
350
400
450
n17 n19 n5 n6 n7 nw1 nw11 nw2 nw3 nw4 nw5 nw6 nw7 nw8 w1 wc1
Numbers of claims 1989-2014
Numbers of claims 1989-2014
camden.gov.uk
• Alder
• Raywood Ash
• Ailanthus
(300 trees in total) (Target trees chosen as they do not adapt well to biennial pollarding and are also frequently involved in claims)
Analysis by post code led to proposing a street tree fell & replacement programme
based on 3 target species of tree:
camden.gov.uk
Raywood Ash
Alder
camden.gov.uk
Felling & replacement programme base on target trees by post code:
0
10
20
30
40
50
60
70
ec1 n1
nw1
nw2
nw3
nw5
nw6
nw8
w1
wc1
wc2
N19
N6
N7
Number of claims 2008-‐2013
Felling program
camden.gov.uk
‘Small’ tree planting in high claim post codes 2011 to 2013:
0
50
100
150
200
250
300
350
N20 N19 N6 NW1 NW2 NW3 NW5 NW6 NW8 W1 WC1 WC2 N1 N7
Other size trees 2011-13
Small size trees 2011-13
camden.gov.uk
Examples of ‘small’ trees being planted:
Prunus ‘Pandora’ Liquidambar ‘Gum Ball’ Malus ‘Adirondack’
camden.gov.uk
Acer platanoides ‘Brilliantissimum’
Acer campestre 'Elsrijk'
camden.gov.uk
Small Tree Species:
Very Small Small Small + Small-‐Med
Acer pseudoplatanus ‘BrillianAssimum’
Prunus x subhirtella ‘Autumnalis’
Malus floribunda Prunus ‘Pandora’
Prunus fru7cosa ‘Globosum’ Amelanchier sp. Malus ‘Evereste’
Sorbus ‘Joseph Rock’
Acer campestre ‘Nanum’ Amelanchier ‘Obelisk’
Sorbus Hupehensis
Pho7nia sp. Malus ‘Rudolf’ Acer platanoides ‘Globosum’ Malus ‘Adirondack’ Liquidamber styraciflua ‘Gum
Ball’
camden.gov.uk
‘Rightsizing’ Camden’s tree stock:
camden.gov.uk
Photinia Amelanchier
camden.gov.uk
Cherry & Ash Winter flowering cherry
camden.gov.uk
Whitebeam Photinia
camden.gov.uk
“It’s still a bit experimental!” Ligustrum Tamarix (Largerstoemia & P. Globosa)
camden.gov.uk
Improving diversity:
13.468%
13.330% 11.927%
11.563%
5.388%
5.025%
4.761%
3.117%
3.005% 2.384%
2.151%
2.098%
1.499%
1.400% 1.273%
1.266%
1.238%
1.181% 1.111% 0.991% 0.875%
0.875%
0.804%
0.769%
0.716%
0.532%
0.434%
0.413%
0.398%
0.398% 0.388%
0.374%
0.342%
0.317% 0.307%
0.300% 0.275%
0.243%
0.219% 0.208% 0.208% 0.208% 0.194% 0.180% 0.169% 0.145% 0.145% 0.127% 0.109% 0.102% 0.074% 0.071% 0.063% 0.060% 0.053% 0.046% 0.046% 0.042% 0.039% 0.035% 0.035% 0.035% 0.032% 0.028% 0.028% 0.028% 0.025%
0.021%
0.021%
0.021% 0.018%
0.018%
0.018%
0.018%
0.018%
0.018%
0.014% 0.014%
0.011%
0.011% 0.007%
0.007% 0.007%
0.007%
0.007% 0.007%
0.007%
0.004%
0.004%
0.004%
0.004%
0.004% 0.004% 0.004%
0.004% 0.004%
0.004%
0.004%
0.004%
0.335%
99 genera currently present in Camden Acer
Platanus
Tilia
Prunus
Fraxinus
Betula
Sorbus
Malus
Crataegus
Ilex
Robinia
Aesculus
Quercus
Sambucus
Pyrus
Amelanchier
Taxus
Alnus
Pinus
Chamaecyparis
camden.gov.uk
• Pruning/crown management does influence tree related subsidence claim
numbers and costs.
• Reduction in street tree canopy cover and eco system services with the planting of small tree species
• Greater emphasis on planting large tree species ‘where appropriate’
Conclusion:
camden.gov.uk
Dave Houghton and Riccardo Arnone
Acknowledgements:
camden.gov.uk
The End
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