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