1. Tree Assessment and Risk Management Certified Arborist Training

3. The value comes at a “price”, however. There are risks associated when trees are in areas used by people and their “things” (targets). Risk assessment includes the potential of a tree to fall, the environment that may contribute to its failure, and the potential target . Evaluating trees for their potential to fail is a component of risk management . Tree Assessment and Risk Management TREES HAVE VALUE!!

4. TORT LAW – A “tort” is a civil wrong; more commonly stated, a non-criminal harm (wrong) done to persons or property. Tort can result from an intentional act (assault, battery, libel) OR may be unintentional (e.g., negligence) NEGLIGENCE – A person is negligent when he or she fails to act as a reasonably prudent person under the circumstances. Ignorance or stupidity are not excuses for dangerous or inappropriate behavior. Tree Assessment and Risk Management RISK AND LIABILITY

8. Basic Tree Biology 90-95% of a Tree’s Root System is located in the Top 3 Feet of Soil! 3 ft 1 ft Even though the tree may be left standing (for now) major trauma to these roots will kill the tree! Roots can grow to twice the height! Tree Assessment and Risk Management 50% of a Tree’s Root System is located in the Top 1 Foot of Soil!!!! These are mostly the absorbing roots that provide WATER and NUTRIENTS

10. As a general rule, the Critical Root Zone should extend at least to the drip line of a tree. If the CRZ cannot be protected… Disturbance may come as close as 5X the diameter of the protected tree on ONLY ONE SIDE!! 5X…then protect the rest!! Tree Assessment and Risk Management

11. Trees grow as if they are actually trees within a tree . Each year’s growth covers and surrounds the previous year’s tissue. If a wound occurs, the tree responds by trying to wall off, or compartmentalize, the wounded area. The tissue from each new year of growth will cover the old wound and remain unaffected, as long as rot or decay does not move into the new tissue. If compartmentalization is effective, the new tissue remains healthy and the old wound is “walled off” or sealed behind the new tissue. (e.g., a hollow tree with sound wood around the hollow.) Tree Assessment and Risk Management Tree Wounding

12. A tree with structural defects likely to cause failure of all or part of the tree, which could strike a target . Tree Assessment and Risk Management Hazard Tree

13. A tree with structural defects likely to cause failure of all or part of the tree, which could strike a target . Tree Assessment and Risk Management Hazard Tree

16. Hazard Tree Report Forms There are several… Most are very detailed and require calculation of a “Hazard Rating” or Hazard Potential . Tree Assessment and Risk Management Inspections

17. Tree Risk Assessment

18. Tree Risk Assessment

19. Tree Risk Assessment

21. Failure + Size + Target = Hazard Potential of part Rating Rating 1 = Low (Minor defects) 2 = Medium (Small to medium cavities within safe limits) 3 = High (Significant defects, serious stem decay) 4 = Severe (Cavity at or beyond safe limits, multiple defects, large dead branches or trees) Tree Assessment and Risk Management

22. Failure + Size + Target = Hazard Potential of part Rating Rating 1 = <6” diameter 2 = 6-18” diameter 3 = 18-30” diameter 4 = >30” diameter Tree Assessment and Risk Management

23. Failure + Size + Target = Hazard Potential of part Rating Rating 1 = Occasional Use (alley) 2 = Intermittent Use (side street) 3 = Frequent Use (main road) 4 = Constant Use (house) Tree Assessment and Risk Management

24. What is the Hazard Tree Rating for this tree? Tree Assessment and Risk Management

27. NOT NEGOTIABLE! Dead wood is unpredictable and should be removed as soon as possible. Dead wood is brittle. Dead Wood Tree Assessment and Risk Management

28. A separation of the wood, a fissure or deep split in the bark and wood. Tree Assessment and Risk Management Cracks HIGH FAILURE POTENTIAL A crack goes completely through the stem or branch. Stem has two cracks on the same segment with a cavity or extensive decay. Stem has crack with another defect (lean, weak branch, etc.).

29. MODERATE FAILURE POTENTIAL Hardwood stem has one crack that has inrolled bark and the internal cylinder of wood is gone or decayed. Tree Assessment and Risk Management Cracks

30. A fork in the stem or union of two or more main branches. Co-dominant stems … U-SHAPED V-SHAPED Tree Assessment and Risk Management Weak Branch Unions

31. HIGH FAILURE POTENTIAL A weak branch union that is also cracked or decayed. A weak union in a tree’s hot spot. Tree Assessment and Risk Management Weak Branch Unions

32. MODERATE FAILURE POTENTIAL A weak union with included bark at the branch bark ridge Tree Assessment and Risk Management Weak Branch Unions

33. Wood that is rotted or missing (visible cavities ). Decay always results in less structural strength and stability. Tree Assessment and Risk Management Decay

34. Injury occurs. Fungi enters the wound and begins to discolor the wood as rot begins. As years pass, the rot column grows in height, but is also covered by new layers of wood from each years new “ring” (tree in a tree). The process continues. After many years of growth, the result is a visible trunk wound with an internal rot column behind it. Tree Assessment and Risk Management Decay

35. Tree Assessment and Risk Management

36. Internal Hollow Exposed Cavity Tree Assessment and Risk Management

37. If shell thickness is less than 1/3 of the stem radius, then the tree is unsafe. Tree Assessment and Risk Management

38. An area of dead bark and cambium anywhere on the tree, often affecting the wood beneath it. Tree Assessment and Risk Management Cankers

39. Problems serious enough to warrant correction are partial windthrow (leaning with mounding, missing roots, and extensive root rot. Problems may be hidden underground. Tree Assessment and Risk Management Root Problems

40. Tree Assessment and Risk Management

41. Tree Assessment and Risk Management

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43. Tree Assessment and Risk Management

44. Check for fruiting bodies at the base of a tree that may indicate serious root rot. This may be the end result!! Tree Assessment and Risk Management Root Problems

45. Soil Compaction Grade Changes Trenching and Excavating Tree Assessment and Risk Management Root Problems

48. TOPPING CREATES WOUNDS THAT LAST A LIFETIME! Tree Assessment and Risk Management Prevention and Correction ( Mitigation )

49. FLUSH CUTS LAST A LIFETIME TOO! Tree Assessment and Risk Management Prevention and Correction ( Mitigation )

50. MOWER DAMAGE Tree Assessment and Risk Management Prevention and Correction ( Mitigation )

51. Consider fencing off hazard trees if removal is not a “popular” option. Tree Assessment and Risk Management Prevention and Correction ( Mitigation )

52. Performing an INVENTORY of trees on property you manage can be the best preventive step you can take!! Tree Assessment and Risk Management Prevention and Correction ( Mitigation )

53. Inventories can provide you with data about the number of hazard trees you have. Tree Assessment and Risk Management Prevention and Correction ( Mitigation )

54. Hazard Tree Web Page: www.na.fs.fed.us/spfo/hazard/index.htm Evaluation of Hazard Trees In Urban Areas is available through the International Society of Arboriculture at www.isa-arbor.com Tree Assessment and Risk Management Additional Sources of Information: