Community Tree Risk Management 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

Community Tree Risk Management 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.

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

Community Tree Risk Management All trees will fail when the load exceeds the strength of the wood. Defective trees will fail sooner than sound trees.

Community Tree Risk Management Defects are visible signs that trees have the potential to fail.

Community Tree Risk Management Defect Categories

Community Tree Risk Management 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

Community Tree Risk Management Advanced decay is always present when fungal fruiting bodies are found: Mushrooms Shelf-fungi Conks

Community Tree Risk Management CRACKS = A separation of the wood, a deep split through the bark and into the wood. Vertical cracks Horizontal cracks

Community Tree Risk Management Shear cracks separate the stem into two halves. Imminent danger

Community Tree Risk Management Inrolled cracks: May be open or closed. Always associated with decay. Always perpetuates itself. Often generates additional cracks.

Community Tree Risk Management Horizontal crack indicates that the tree is already failing. Runs across the grain Imminent danger

Community Tree Risk Management A seam is the final phase in the wound-sealing process. Evaluate shell thickness

Community Tree Risk Management ROOT PROBLEMS = Inadequate anchoring by root system; damaged roots, restricted roots. Severed Crushed Decayed Missing Confined

Community Tree Risk Management excavating, trenching, paving, regrading, or, soil compaction. Damaged roots caused by…

Community Tree Risk Management Symptoms of root problems: Crown decline Soil-root disturbance Leaning tree Roots confined

Community Tree Risk Management Loss of anchoring becomes apparent when a tree develops a new lean. Soil mounding Broken roots

Community Tree Risk Management Strong branch unions: Upturned Branch Bark Ridge (BBR) Internal wood-to-wood connections Branch is same age as stem

Community Tree Risk Management Weak unions due to included bark: Bark is growing inside the tree No branch bark ridge Internal wood-to-bark “connection”

Community Tree Risk Management Weak unions due to epicormic branches are common on topped trees and near pruning wounds.

Community Tree Risk Management Leaning trees that are stabilized: Problem if lean >40 degrees. Problem if have moderate defect in lower stem.

Community Tree Risk Management Problems with branch architecture: Twist, bend or crook in branch Multiple branches from 1 location Branches rub together Abnormal pattern of growth

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