What do we really know–and not know–about the costs of performing less than optimal maintenance? How do investments in structural pruning, health care, mulching and even watering maintenance practices stack up against the cost of NOT providing optimal levels of maintenance for urban trees? Analysis of data from the literature review includes risk assessment, pest economics, IPM, costs of removal and tree mortality.

1. The Cost of Not
Maintaining Trees
Supported by a contract from the ISA, Science & Research Committee, 2012-2014
Presenter: Dr. JESS VOGT
Co-authors: Dr. RICH HAUER*
*Thanks to Rich for the use of many of his slides in
this talk!
Dr. BURNEY FISCHER
SARAH WIDNEY

2. Outline
• Context: “The costs of not maintaining trees”
• Costs of maintaining & not maintaining
• In municipal budgets:
• Planting
• Pruning
• Not in municipal budgets:
• Watering
• Back-of-the-envelop costs and benefits in Indianapolis
• Strategies for future research & practice

3. 2 published articles
Arboriculture&UrbanForestry41(6):November 2015 293
The Cost s of M aint aining and Not M aint aining
t he Urban Forest : A Review of t he Urban
Forest ry and A rboricult ure Lit erat ure
Arboriculture& Urban Forestry 2015. 41(6): 293–323
Arboriculture&UrbanForestry41(6):November 2015 293
Jess Vogt , Richard J . Hauer, and Burnel l C. Fischer
The Cost s of M aint aining and Not M aint aining
t he Urban Forest : A Review of t he Urban
Forest ry and A rboricult ure Lit erat ure
Arboriculture& Urban Forestry 2015. 41(6): 293–323
Arboriculture&UrbanForestry41(6):November 2015 293
Jess Vogt , Richard J . Hauer, and Burnel l C. Fischer
The Cost s of M aint aining and Not M aint aining
t he Urban Forest : A Review of t he Urban
Forest ry and A rboricult ure Lit erat ure
Arboriculture& Urban Forestry 2015. 41(6): 293–323
cONt iNUiNg eDUcat iON UNit
Indeed,what’stheworst that canhappen—except,possibly,
payingmorelater than what wewouldpayin thepresent.
A literaturereview of more than 300 paperson tree
maintenancein thef eldsof arboricultureand urban for-
estryset out toanswer thequestion:What arethecostsof
not maintainingtreesand theurban forest?T eliterature
review produced adetailed summary of 163 papersthat
discussed maintenancecostsin thecontext of thebenef ts
ofurbantreesandrevealedhowlackofmaintenanceimpacts
futurevalue.Common urbanforest operations(planting,
pruning, removal, pest and disease management, and
infrastructurerepair) andother important activitiesaf ect-
ingtreelongevity(treerisk management, watering, mulch-
ing, nutrient management, treesupport systems, andtree
protection) wereincluded in thisstudy. T eresultsshed
light on our current stateof knowledgeof theeconomics
of urbantreemanagement,withemphasisonmaintenance
activitiesused to increaseservicelifeand providegreater,
Objectives
Identify theelementsof an urban forest maintenanceframework
Describecomponentsused in assessingthecostsand benef tsof
urban trees
Summarizethresholdsfor determiningoptimal pr uningcycles
Evaluatethelink between treemaintenanceactivitiesand urban
forest benef ts
CEUsforthisarticleapplytoCertif edArborist,UtilitySpecialist,
Municipal Specialist,TreeWorker Climber/Aerial Lift Specialist,
andtheBCMAmanagement category.
Most peopleget excitedwithnewthings,likecars,buildings,
andyes,newlyplantedtrees.But what wasoncenew,soon
becomesold, andwith agecomesthequestion of mainte-
nance. Preventiveor proactivemaintenancesetsthestage
to providegreater servicelife, and if donecorrectly, pre-
T he Cost of N ot
Maintaining the
Urban Forest
ByRichardJ. Hauer, JessicaM. Vogt, andBurnell C. Fischer
www.isa-arbor.com
Extent What part of atreeor which trees Branchesbelow 14-foot (4.27 m) clearancelevel, all treesin a
heavily traveled road corridors, treesin adowntown area

4. • Benefits of the urban forest well researched
• Costs of the urban forest less understood
• Municipal budget expenditures used in cost-benefit analyses of
the urban forest
• Tree maintenance funding at the municipal level is limited
• Non-essential and frequently on the chopping block during
budget cuts
“The costs of not
maintaining trees”

5. “The costs of not
maintaining trees”
• ISA commissioned literature review
• Literature review RFP:
“A substantial percentage of total expenditures are a
consequence of deferred maintenance that results in tree
failures, electric service interruptions, and damage to urban
infrastructure that threatens public safety and welfare.
Scheduled, routine maintenance aimed at preventing tree
failures and infrastructure conflicts may save more in the
long-run than it costs in the short-term.”
BUT HOW MUCH?

6. MAINTENANCE
Activities
 Planting
 Pruning
 Removal
 Etc.
Tree & Urban Forest
STRUCTURE
 Establishment
 Survival
 Growth
 Condition
 Size
 Canopy Cover
 Leaf Area
 Etc. FUNCTION
 Evapotranspiration
 Photosynthesis
 Intercept Rain
 Etc. BENEFITS
 Stormwater Runoff
Reduction
 Carbon Stored
 Etc.
VALUE
$$$
Less-than-
optimal
MAINTENANCE
leads to fewer
BENEFITS
produced by the
urban forest.

7. Costs/Benefits over time

8. Literature review
Our task:
Review the literature on the costs of
maintaining and not maintaining trees
from within the field of
arboriculture/urban forestry.

9. Literature review
• Collected and read ~400 articles
• ~150 within arboriculture/urban forestry deemed “useful” and
“relevant” (incl. utility management literature)
• 95 discussed economic costs
• 65 of these actually calculated costs (others inferred)

10. Journals ~110 from JOA/AUF
~10 from UF&UG
Journal of
Arboriculture
Arboriculture &
Urban Forestry
Urban Forestry &
Urban Greening
Journal of
Environmental
Horticulture
Landscape and
Urban Planning
Arboriculture
Journal

11. Publications per year
0
20
40
60
80
100
120
1975 1980 1985 1990 1995 2000 2005 2010 2013
#ofpublications
Year
Total publications
Publications per year

12. Lit review results
GENERAL OBSERVATIONS
• Few articles on the costs of not maintaining urban trees
(economic or otherwise)
• Two places where they do appear within A&UF lit:
• Utility Management
• Pest/Disease Management
• Costs of maintenance somewhat examined
• Surveys of municipal budget expenditures, contracting costs
• Biological/ecological costs of maintenance activities  tree
survival, growth

13. Types of maintenance
0 5 10 15 20 25 30 35 40
Other
Appraisal
Protection
Tree support systems
Soil/nutrient mgmt
Mulching
Watering
Tree risk mgmt
Pest/disease mgmt
Infrastructure repair
Removal
Planting
Pruning
Multiple/Many
Number of articles

14. Types of maintenance
0 5 10 15 20 25 30 35 40
Other
Appraisal
Protection
Tree support systems
Soil/nutrient mgmt
Mulching
Watering
Tree risk mgmt
Pest/disease mgmt
Infrastructure repair
Removal
Planting
Pruning
Multiple/Many
Number of articles
Maintenance in
municipal budget
Maintenance NOT
in municipal budget

15. 0 5 10 15 20 25 30 35 40
Other
Appraisal
Protection
Tree support systems
Soil/nutrient mgmt
Mulching
Watering
Tree risk mgmt
Pest/disease mgmt
Infrastructure repair
Removal
Planting
Pruning
Multiple/Many
Number of articles
Municipal maintenance
Includes utility
pruning
Includes IPM

16. Common types of
maintenance in municipal
budgets
• Planting
• Pruning
• Removal
• Infrastructure repair
• Pest/Disease Management

17. Per-tree expenditures
o maintain public trees. An average $42.59 (4.49 SEM) per street tree was spent
4 (Figure 2-2). This includes all costs associated with activities (e.g., planting,
anagement, removal). A $37.50 (3.02 SEM) amount was spent on all public trees
parks, and other public locations. No apparent difference was found by population
, the South region had the greatest per tree spending and also the most variable
by the
the mean
he total forestry
o the entire
et is one
pare forestry
nally a mean
M) of the total
et was allocated
ties (Figure 2-
cation was
Midwest
in the
%) and
he South
st (0.44%)
gest cities
ore people)
Figure 2-2. Annual budget spent per street tree (n=230) and per
42.59
66.10
24.23
29.91
64.35
34.63
39.68
45.78
28.34
35.23
37.50
25.74
68.14
24.58
44.85
36.17
37.35
44.45
27.02
21.97
0 20 40 60 80 100
Total, all cities
Over 1,000,000
500,000 - 1,000,000
250,000 - 500,000
100,000 - 249,999
50,000 - 99,999
25,000 - 49,999
10,000 - 24,999
5,000 - 9,999
2,500 - 4,999
Annual Budget Per Tree ($)
PopulationGroup
All Public Trees
Street Trees
(Hauer & Peterson 2014)

18. Figure 2-6. Temporal effect of emerald ash borer (Agrilus planipennis Fairmaire) on municipal forestry
Level of maintenance performed
impacts overall municipal expenditures
(Hauer & Peterson 2014)

19. Municipal Forestry ActivitiesFigure 2-6. Temporal effect of emerald ash borer (Agrilus planipennis Fairmaire) on municipal forestry
budgets as a percentage of the total municipal budget. (n=366). Adapted from Hauer and Peterson 2016
Figure 2-7. Percent of forestry budget spent on tree activities in states with a confirmed emerald ash(Hauer & Peterson 2014)

20. PLANTING (& NOT PLANTING)

21. Costs of planting
• Surveys of U.S. cities: ~14% of municipal tree budgets (Kielbaso et
al. 1982; Kielbaso 1990; Hauer & Peterson 2014)
• Properly planted trees  less maintenance needed (Harris 1985)

22. Costs of planting
• Surveys of U.S. cities: ~14% of municipal tree budgets (Kielbaso et
al. 1982; Kielbaso 1990)
• Properly planted trees  less maintenance needed (Harris 1985)
• BUT
• Site design…proper planting depth…

23. Non Apparent Norway Maple Decline Initial Decline
Abiotic stress often leads to biotic failure

24. Moderate Norway Maple Decline Advanced
Abiotic stress often leads to biotic failure

25. The Root of the Cause: Stem Girdling Roots (SGR’s)
Sugar maple with 100% SGR’s with decline evident

26. How Soon Can SGR’s Form?
Little leaf linden 1 year after planting 10 inches deep.

27. How Soon Can SGR’s Form?
Freeman maple 4 years after planting 6 inches deep.

28. Percent of Stem Encircled by Roots Related to Depth.
Borst and Johnson 1999
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10 11
Depth (inches)
PercentEncircled
Ash
Linden

29. y = -0.2333x + 10.322
R² = 0.0728
y = -0.3866x + 9.8348
R² = 0.2199
0
1
2
3
4
5
6
7
8
9
10
11
12
0 1 2 3 4 5 6 7 8 9 10
Conditionrating
Depth (inches)
Depth to Lateral Roots and Stem Girdling Roots
(SGR's) Reduces Sugar Maple Tree Condition
No SGR's
Have SGR's
Linear (No SGR's)
Linear (Have SGR's)
Linear (Have SGR's)
Johnson and Johnson 1997

30. • 73% of Little leaf linden’s
• 17.8% of all tree failures
• 30.1% of all tree failures outside of storm center’s
• 50% of trees in 6 to 10” DBH with SGR’s
Storms of 1998 and Tree Failures’
Trees Planted to deep and SGR’s

31. • Tree decline and death 82% of time
• Sudden failure of tree 18% of time
Stem Girdling Roots and Tree Loss
What practitioners said in 1997 Survey

32. • 125,000 X 18% = 22,250 trees lost
• 22,500 X $500 = $11 Million
Preventable Loss
Tree Value Only
Economic Impact of Deep Root Systems and SGR’s
and estimated 125,000 lost: the Storms of 1998 in MN

33. Costs of NOT planting
Example:
• McPherson (2001): “benefits foregone” due to not planting
shade trees in Sacramento parking lots = $1.4-2.5 mil annually

34. • Years before benefits = costs of tree planting?
– Public housing sites 9 years
– Yard/street trees 13-14 years
– Parks & highways 15 years
• All sites Chicago region (McPherson 1993, GTR NE-186)
Benefits of Trees … Benefit of Time
Tree payback … break even time in different locations

35. -200
0
200
400
600
800
1000
1200
1400
1600
0 5 10 15 20 25 30 35 40
NetTreeValue($1000s)
Years into Future
Full Stocking
Replacement
No Planting
Net Tree Value = Annual Tree Value (CTLA) – Annual Management Costs
Costs of not planting a forest
Miller & Marano 1984

36. PRUNING (& NOT PRUNING)

37. Costs of pruning
• Most expensive item (20-30%) in tree budget (Kielbaso et al. 1982; Kielbaso
1990; Hauer et al 2014)
Utility line pruning:
• Costs of not pruning = power outages, lost service billing time,
repair costs, more pruning later
• Browning & Wiant (1997) – “The economic impacts of
deferring electric utility tree maintenance”
• For every $1 of routine maintenance deferred, more than $1 must
be spent later to make up.
Other studies: Baker & French 1985; Browning & Wiant 1997; Carvell 1978; Churack et al. 1994; Evans & Klett 1985;
Henning 1990; Hensley 1979; Holewinski & Johnson 1983; Johnstone 1988; Kane 2008; Kennedy 1990; Kuntz et al. 2002;
Luley et al. 2002; Miller & Sylvester 1981; Nowak 1990; Nowak et al. 2002; Ulrich 1983; Yamamoto 1985

38. Costs of not pruning
Miller & Sylvester 1981
• Miller & Sylvester
(1981) – “An
economic evaluation
of the pruning cycle”
• Municipal trees in
Milwaukee, WI
• More years since last
pruning  lower
condition class rating

39. Costs of Pruning
Pruning a necessary part of tree structure and health

40. Formative Pruning
Pruning a necessary part of tree structure and health

41. Included Bark
Maturing: Now which limb to remove?
What will the tree look like, how will it respond?

42. Maturing: Where to Prune
Hackberry and decay from included bark

43. • Ryder and Moore 2013
• $2.79 (AUD) Formative pruning new tree
• $44.59 (AUD) Structural prune mature tree
• ~20 times less costly to
structural prune
Costs of Formative Pruning
Pruning a necessary part of tree structure and health

44. Maintenance not generally
itemized in city budgets
• Tree risk management
• Watering
• Mulching
• Fertilizing/Nutrient Management
• Staking/Bracing/Cabling
• Protection (e.g., during construction)

45. Maintenance not generally
itemized in city budgets
• Tree risk management
• Watering
• Mulching
• Fertilizing/Nutrient Management
• Staking/Bracing/Cabling
• Protection (e.g., during construction)

46. WATERING (& NOT WATERING)

47. Costs of watering
• Watering = 2.6-4.6% of municipal tree expenses,
when itemized (Kielbaso 1990; Hauer & Peterson 2014)
• Watering crucial to planted tree establishment &
survival
• Costs of not watering = decreased tree condition,
mortality
• Few studies on economic costs of not watering

48. Transplant Shock … Establishment Indicators
Allocation of Resources (Smaller Foliage & Reduced Shoot Growth)
Prior to
Harvest
1 2
3
H2O Stress and Multiple Leaders

49. Number of Trees Percent
Treatment Planted Dead Survival
Plastic container 14 6 57
Plastic container with SpinOut 14 8 43
Air root-pruning (ARP) 14 7 50
Low-profile ARP container 14 10 29
Root-pruned, field-grown B&B 14 0 100
Non-root-pruned, field-grown B&B 14 4 71
Costs of not watering during
establishment = mortality
Gilman (2001):
Irrigation = no mortality
No irrigation = heavy mortality for most production methods
1 yr after transplant

50. Savings from not watering
during establishment
Gilman 2001
Cost per live tree
Treatment Irrigation No Irrigation Savings
Plastic container 445 588 143
Plastic container with SpinOut 445 784 339
Air root-pruning (ARP) 445 672 227
Low-profile ARP container 445 1,176 731
Root-pruned, field-grown B&B 383 274 -109
Non-root-pruned, field-grown B&B 383 383 0
Inferred from costs of watering (contractor estimates)

51. Water
Prescription
Appropriate Doses of Water

52. An Urban Forest … Response to
Emerald Ash Borer
$-1,050

53. Net Benefit of EAB Management
EAB Management Works, If you like it or not EAB will costs

54. Take-aways from existing
literature
• Lack of maintenance  tree death = easy to quantify costs
• Lack of maintenance  decline in condition = more difficult
to quantify
• Maintenance + tree appraisal value: few articles that use data
• Maintenance + liability for damages: few articles that use data

55. COMPARING COSTS TO BENEFITS
OVER TIME
Back-of-the-envelop calculations

56. Comparing benefits to costs
in Indianapolis
• Inventoried 1,076 trees planted 3-5 years ago by Keep
Indianapolis Beautiful
• Calculated benefits for this population of trees in i-Tree at time
of inventory and projected benefits 5- and 10-years out under 6
scenarios:
• Survival:
• Establishment-phase survival
• 96.4% survival
• No additional mortality
• Growth:
• Average growth
• 40% faster growth

57. Annual Benefits for 1,076 trees
Re-inventory 5-Year Projection 10-Year Projection
EstimatedTotalAnnualBenefits
$0
$10,000
$20,000
$30,000
$40,000
Indianapolis
40% faster growth
Establishment survival
96.4% annual survival
No add’l mortality

58. Annual Benefits for 1,076 trees
Re-inventory 5-Year Projection 10-Year Projection
EstimatedTotalAnnualBenefits
$0
$10,000
$20,000
$30,000
$40,000
Indianapolis
40% faster growth
Establishment survival
96.4% annual survival
No add’l mortality

59. Cumulative Benefits - Indy
Keep Indianapolis Beautiful estimated costs per tree:
$100 to plant a tree
+ $100 per year * 2 years to water
= $300 total per tree establishment costs

60. Cumulative Benefits - Indy
Keep Indianapolis Beautiful estimated costs per tree:
$100 to plant a tree
+ $100 per year * 2 years to water
= $300 total per tree establishment costs
Increasing
survival and
growth rates
decreases
payback period

61. STRATEGIES FOR FUTURE
RESEARCH & PRACTICE

62. MAINTENANCE
Activities
 Planting
 Pruning
 Removal
 Etc.
Tree & Urban Forest
STRUCTURE
 Establishment
 Survival
 Growth
 Condition
 Size
 Canopy Cover
 Leaf Area
 Etc. FUNCTION
 Evapotranspiration
 Photosynthesis
 Intercept Rain
 Etc. BENEFITS
 Stormwater Runoff
Reduction
 Carbon Stored
 Etc.
VALUE
$$$
Less-than-
optimal
MAINTENANCE
leads to fewer
BENEFITS
produced by the
urban forest.

63. Strategies for research & practice
• More studies that quantify the relationship between tree
condition and the level of benefits provided (i.e., benefits
foregone when condition declines)

64. • More studies that quantify the relationship between tree
condition and the level of benefits provided (i.e., benefits
foregone when condition declines)
• Models that examine investment scenarios for combinations of
maintenance activities
Strategies for research & practice

65. • More studies that quantify the relationship between tree
condition and the level of benefits provided (i.e., benefits
foregone when condition declines)
• Models that examine investment scenarios for combinations of
maintenance activities
• (Eventually…) Tools for practitioners to use to determine how
to allocate scarce maintenance resources
Strategies for research & practice

66. • More studies that quantify the relationship between tree
condition and the level of benefits provided (i.e., benefits
foregone when condition declines)
• Models that examine investment scenarios for combinations of
maintenance activities
• (Eventually…) Tools for practitioners to use to determine how
to allocate scarce maintenance resources
• More studies that link specific maintenance activities and their
cost to subsequent tree survival, condition, etc.
• Levels of maintenance
Strategies for research & practice

67. Maintenance regime: levels of maint.
• Maintenance v. no maintenance = too simple
• More maintenance v. less maintenance
Element Explanation Examples
Intensity How much 20% of the crown, 5 gallons of water, etc.
Frequency How often 4- or 6-year pruning cycle, once per week,
etc.
Duration How long For just the first growing season after
transplant, etc.
Extent What part of a tree,
Which trees
Branches below 8 ft. sidewalk clearance,
street trees only, etc.
Type Particular maintenance
activity
Prune, mulch, water, etc.
Who Party performing
maintenance
City tree crews, contracted certified
arborist, adjacent homeowner, etc.

68. What data do we need?
• Three key pieces of information:
• For a particular type of maintenance activity (e.g., pruning),
performed by a particular party (e.g., city tree crews)
1. Level of maintenance (intensity, frequency, duration, extent)
2. Tree outcomes (e.g., survival, condition)
3. $ cost of maintenance
• Furthering models of the costs of not performing maintenance:
Imagine an i-Tree, or Tree Benefits Calculator, where you can
enter information about a tree and then calculate it’s lifetime
benefits under given maintenance regimes (i.e., maintenance
investment).

69. QUESTIONS?
Dr. Jess Vogt
jess.vogt@depaul.edu
(920) 850-2016
www.lufa-depaul.org
“Costs…” project research papers:
Vogt, Hauer, & Fischer (2015) The costs of maintaining and not maintaining the urban
forest. Arboriculture & Urban Forestry 41(6): 293-323.
Hauer, Vogt & Fischer (2015) What is the cost of not maintaining the urban forest?
Arborist News 24(1): 12-17.
The “back-of-the-envelop” portion of this presentation was based in part on:
Widney, Fischer, & Vogt (2016) Tree mortality undercuts ability of tree-planting
programs to provide benefits: Results of a three-city study. Forests 7(3): 65.