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Risk & Hazard Assessment Review

Risk & Hazard Assessment Review. Dudley R. Hartel, Center Manager Urban Forestry South Athens, Georgia. Urban Tree Disaster Assessments Urban Forest Strike Team Training Providence Ridge, VA July 16-18, 2008. Detecting and Assessing Hazardous Defects in Trees.

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Risk & Hazard Assessment Review

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  1. Risk & Hazard Assessment Review Dudley R. Hartel, Center Manager Urban Forestry South Athens, Georgia Urban Tree Disaster Assessments Urban Forest Strike Team Training Providence Ridge, VA July 16-18, 2008

  2. Detecting and Assessing Hazardous Defects in Trees Cynthia L. Ash, PhD, Plant Pathologist USDA Forest Service Northeastern Area State & Private Forestry Durham, New Hampshire Tree Risk Assessment Training University of Maryland and Maryland Forest Service May 25-26, 2004 This presentation was developed by Jana Albers for Risk Assessment Training in St. Paul Minnesota, in September 2003.

  3. Hazard, Risk & Storms • Does risk assessment change? • Concepts don’t… • Acceptable risk may (does)… • Who is paying the bill? • FEMA • Community

  4. All trees will fail when the load exceeds the strength of the wood. Defective trees will fail sooner than sound trees.

  5. Defectsare visible signs that trees have the potential to fail.

  6. Defect Categories

  7. All defective trees cannot be detected, corrected or eliminated. • Some internal defects are not easily detected. • Defect severity changes with time. • Trees are masters of covering up defects and surviving. • By doing inspections and acting on them, we can successfully manage the risk of failure in our urban forests. Disclaimer

  8. Advanced decay is always present when fungal fruiting bodies are found: Mushrooms Shelf-fungi Conks

  9. CRACKS = A separation of the wood, a deep split through the bark and into the wood. Vertical cracks Horizontal cracks

  10. Shear cracks separate the stem into two halves. Imminent danger

  11. Inrolled cracks: May be open or closed. Always associated with decay. Always perpetuates itself. Often generates additional cracks.

  12. Horizontal crack indicates that the tree is already failing. Runs across the grain Imminent danger

  13. A seam is the final phase in the wound-sealing process. Evaluate shell thickness

  14. ROOT PROBLEMS • = Inadequate anchoring by root system; damaged roots, restricted roots. • Severed • Crushed • Decayed • Missing • Confined

  15. Damaged roots caused by… excavating, trenching, paving, regrading, or, soil compaction.

  16. Symptoms of root problems: Crown decline Soil-root disturbance Leaning tree Roots confined

  17. Loss of anchoring becomes apparent when a tree develops a new lean. Soil mounding Broken roots

  18. Strong branch unions: • Upturned Branch Bark Ridge (BBR) • Internal wood-to-wood connections • Branch is same age as stem

  19. Weak unions due to included bark: Bark is growing inside the tree No branch bark ridge Internal wood-to-bark “connection”

  20. Weak unions due to epicormic branches are common on topped trees and near pruning wounds.

  21. Leaning trees that are stabilized: Problem if lean >40 degrees. Problem if have moderate defect in lower stem.

  22. Problems with branch architecture: Twist, bend or crook in branch Multiple branches from 1 location Branches rub together Abnormal pattern of growth

  23. INSPECTIONS Tree risk inspections: Systematic examination of individual trees Assess defects Estimate potential for failure based on accepted signs and symptoms of tree failure.

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