ISA Certified Arborist

International · International Society of Arboriculture · professional · unverified source

73practice questions written to this syllabus
2subjects

Format

Unverified. Computer- or paper-based multiple-choice exam after qualifying arboricultural experience or a related degree; recertification by continuing education.

Sections

Over the years

Unverified: the ISA page fetched confirmed the credential and its exam outline document but not the numbers. Used worldwide in urban forestry and arboriculture.

Official source: https://www.isa-arbor.com/

Subjects this exam draws on

Tree Physiology9 questionsUrban Forestry & Arboriculture64 questions

Five practice questions, worked

Original questions written to this exam's published syllabus and pattern. Not past papers.

1. Why are ring-porous trees with wide earlywood vessels more vulnerable to freeze–thaw embolism than conifers?

  1. Wide vessels contain more sugar, which lowers their freezing point
  2. Conifer tracheids are alive, so they repair embolism immediately
  3. Wide vessels are never under tension and fill with air in winter
  4. Thawing leaves larger bubbles in wide conduits, which then expand
Answer and working

D. Thawing leaves larger bubbles in wide conduits, which then expand

Dissolved air forms bubbles on freezing; in wide conduits the bubbles are large enough to expand into embolisms when tension resumes. Narrow tracheids produce small bubbles that redissolve.

Tree Physiology · Water relations: transpiration, cohesion-tension, xylem embolism

2. In the 3-30-300 rule, '30' refers to:

  1. 30 trees visible from each home
  2. 30% canopy in every neighbourhood
  3. 30 m to the nearest park
  4. 30 years of tree lifespan
Answer and working

B. 30% canopy in every neighbourhood

3 trees visible, 30% canopy, 300 m to a park.

Urban Forestry & Arboriculture · Urban forest concepts and benefits

3. Late spring frosts cause most damage to trees because:

  1. Bark is thickest in spring and traps cold
  2. Roots stop absorbing water in spring
  3. Buds harden fully only after leaf-out
  4. Trees deacclimate rapidly after bud break
Answer and working

D. Trees deacclimate rapidly after bud break

Hardiness is lost quickly as growth resumes, so new shoots and flowers are killed at temperatures that dormant buds would survive.

Tree Physiology · Dormancy, phenology and cold hardiness

4. LiDAR is valuable in canopy assessment mainly because it also measures:

  1. Tree species by smell
  2. Tree height
  3. Soil nutrient levels
  4. Leaf chemistry
Answer and working

B. Tree height

Three-dimensional data.

Urban Forestry & Arboriculture · Urban tree inventory and canopy-cover assessment

5. 'Volcano mulching' is harmful because mulch piled against the trunk:

  1. Conserves too much water
  2. Bark decay, girdling roots
  3. Kills weeds around the tree
  4. Moderates soil temperature
Answer and working

B. Bark decay, girdling roots

Keep mulch away from the trunk.

Urban Forestry & Arboriculture · Tree planting and establishment in urban soils

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