Identifying Hazardous Trees;Identifying Hazardous Trees; INTRODUCTION

Beau BrodbeckAlabama Cooperative Extension System

The workshop today……The workshop today……

Part 1: Introduction to urban forestry and hazard tree identification

Part 2: Introduction to the ISA Visual Guide to Risk AssessmentPart 2: Introduction to the ISA Visual Guide to Risk Assessment

Part 3: Tree Defects; the Roots

Part 4: Tree Defects; the Trunk

Part 5: Tree Defects; the Crown

Part 6: Outdoor PracticumPart 6: Outdoor Practicum

Cities and Towns Happen

• 307,006,550  US citizens (2009) 

• 25,375 places

• 106.3M developed acres

• 295.9B ft² of built space

• Alabama– 4.7 M citizens– 453,760 developed acres, p

Urban Trees HappenUrban Trees Happen

• 3.82 billion urban trees

• 3.5% US land space

• Contains 75% population

• Average 27.1% canopy cover

H ll t ft th llid !However, all too often they collide!

• Diseased Trees

• Dead Trees

• Tree Failure• Tree Failure…

Trees can be dangerous…Trees can be dangerous…

Hurricane Ivan, Brewton, ALPhoto by Charles Nesbitt, Birmingham News

Threaten Public Safety

Can some of this be prevented…pThe answer is Yes

Better Tree Placement and design

Minimizing damage from construction utilities & poorconstruction, utilities, & poor arboriculture

Regular urban tree assessments &maintenance& maintenance

So why are trees worth the risk?

Aesthetics

Make our communitiescommunities more livable

St AugustineSlide by: Ed Gilman

However, there is more than beauty… yPsychological Benefits

Stress reduction

Shorter hospital stays & use less meds for patients with landscape viewsp

Lower domestic violence

Children with A D D haveChildren with A.D.D. have better behavior in green environments

There is more than emotion… $$$

Energy Savings!!!

• Auburn residential study showed

gy g

Auburn residential study showed that 17% shade saved $10/month on power bill.

• Same study also showed 50% shade saved $28/month

• California has controversy of tree shad vs. solar panels…

More trees = higher property values

Each mature front lawn shade tree adds ~1% to home property lvalue

Shoppers purchase 12%

Fairhope, AL

The list of tree benefits is long… 

• Water retention in canopy (28%)• Water retention in canopy (28%)

• Trees cool by 10‐20 degreesy g

• C02 reduction (3%)

• Streets w/ little or no shade need re‐paving twice as often as thosere paving twice as often as those with 30% tree cover

• Etc…

Most of us can agree trees are good…g g

However…We don’t always know how to get therehow to get there…

What makes a hazardous tree?What makes a hazardous tree?

A hazard tree has a structural defect that may cause the tree or a portionthat may cause the tree or a portion of the tree to fall on someone or something else of value (N i lsomething else of value. (National 

Arborday Foundation)

Hazard Tree Identification ProcessHazard Tree Identification Process1. Tree Characteristics2. Overall Tree Health3. Site Conditions4. Target5. Tree Defects

a) Root Defectsb) Trunk Defects) C D f tc) Crown Defects

6. Hazard rating7 Ha ard abatement7. Hazard abatement8. Comments

Tree CharacteristicsTree Characteristics

• Collect and consider information on tree’s:Collect and consider information on tree s:– Species

DBH I t t t k t– DBH

– Height

S d

Important to know tree species and associated growth characteristics– Spread

– Crown class

P i hi

growth characteristics and expected responses to wounds, maturity 

– Pruning history

– Special value,etc…

Lafayette, Louisiana

Tree HealthTree Health

• Collect and consider information on tree’s:Collect and consider information on tree s:– Foliage color

Foliage density– Foliage density

– Woundwood 

d l tTree healthy can be an 

development– Vigor

indicator of some structural problems 

and should be considered when 

factoring tree hazards

Site ConditionsSite Conditions

• Collect info on…Collect info on…– Site character

• Residence etc…L d

Site conditions help evaluation by knowing:

– Landscape type• Yard, curb etc…

– Site disturbance

g•Regional weather to evaluate windthrow

•Degree of site change helps evaluate potential damage and rot likely in the

• % paved etc…– Obstructions

• Overhead and below ground lines

potential damage and rot likely in the roots

Overhead and below ground lines– Exposure to wind

• Likelihood of windthrow

Targets…Targets…

“the target component of a hazard rating is thethe target component of a hazard rating is the people and property that would be injured or damaged should a failure occur” 

Matheny & Clark

Occupancy – inspector must anticipate use of the siteOccupancy – inspector must anticipate use of the site around trees.

• Sites used 24 hours a day have a higher hazard rating than those used seasonally

Targets; Use under tree…Targets; Use under tree…

BuildingParkingTrafficPedestrianPedestrianRecreationLandscapeHardscapeHardscapeSmall featureUtility lines

Target; OccupancyTarget; Occupancy

Constant useConstant use

Frequent useHazard rating i i h

Intermittent use

increases with increasing use…

Occasional useWhat is the probability that a targetWhat is the probability that a target will be present during the most likely 

failure event before the nextfailure event, before the next evaluation

Targets…Targets…

NOT ALL TARGETS ARE CREATED EQUALNOT ALL TARGETS ARE CREATED EQUAL

Tree Defects:Tree Defects:

R t d f t T k d f t C d f tRoot defects     Trunk defects   Crown defects

Hazard Rating, Abatement & Comments

• Hazard RatingHazard Rating….

Failure potential + Size of Part + Target Rating = Hazard Rating

• Abatement:Wh i d b i ?What are you going to do about it?

C t• Comments:Inform your client of any special considerations

A few things that can help you identify h dhazard trees…

• 1.  Know your trees (Tree ID)

• 2.  Know some basic tree biology

• 3.  Understand tree structure

• 4.  Understand tree mechanics

• 4 Experience4.  Experience…

Helpful tools for evaluating trees…Helpful tools for evaluating trees…

CameraDiameter tapeIncrement borerSoil augerSoil augerChisel or surveyors

Resistograph

Tree RadarTree Radar

Specialized arboricultural tools …Specialized arboricultural tools …

AirspadeAirspade

Evaluations forms and hazard rating systems…

• There are several systems out there and they all have pluses and minusesall have pluses and minuses

• Basically they help remind assessors of what to look for and how to categorize their thoughts, comments and report findings…

Tree Risk Assessment; Systematic lEvaluation Process

Dr. Kim D. Coder, Univ. GA 1990

Coder’sCoder s Method…

Bartlett Tree Research Lab

E. Thomas SmileyBruce R. FraedrichNeil HendricksonNeil Hendrickson

Bartlett’s Method…

USDAUSDA Community Tree Risk 

AssessmentAssessment

Jana AlbersJana AlbersJill PokornyDr. Gary Joshnson

Photographic g pGuide to the Evaluation ofEvaluation of Hazard Trees in Urban Areas

Nelda MathenyJim Clark

Photographic Guide to the EvaluationPhotographic Guide to the Evaluation of Hazard Trees in Urban Areas

Why did we pick this guide for today?Why did we pick this guide for today?

1.Relatively easy to use and understand.Relatively easy to use and understand2.Incorporates tree health into the process3.Incorporates tree characteristics and site pconsiderations into the process

4.It provides for good record keeping if you p g p g yever need to re‐visit the tree