Tree assessment, evaluation, and risk

Tree structure and biology

• Introduction
• Wood
• Root system
• Lower trunk
• Trunk, branches, and unions
• Canopy
• Force distribution
• How trees grow

Tree defects

• Decay development

Reducing risk

• Limit large low branch removal
• No flush cuts
• Pruning
• Planting properly
• Avoid root damage
• Structural pruning

Potential causes of risk

Tree strength and weakness

• Strength of different trees
• Strength of different parts
• Strength reduces with age

Impairment of uniform stress distribution

• Distribution of loading
• Interruption of growth by living agents
• Inadequate root anchorage

Damage to existing support

• Direct physical injury
• Cracks from mechanical loading
• Decay
• Risk not related to mechanics

Remedial Actions

• Move the target
• Remove the defective tree or parts
• Reduce the load on defective part
• Root collar exam and treatment
• Artificial systems
• Hire an arborist