Post on 24-Mar-2018
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…
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
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
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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…
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
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
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…
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