ISA Cheat Sheet 2026

The 30 highest-yield ISA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. How does tree bark protect the tree? → Protects from pests and environmental damage
2. How can tree roots be protected during construction? → By fencing off the root zone
3. How do trees adapt to drought conditions? → Reduce leaf growth
4. What is the recommended mulch depth when mulching around a newly planted tree? → 2–4 inches
5. What is the purpose of a 'tailboard safety briefing' conducted before the start of each job? → To communicate the job plan, identified hazards, and safety measures to all crew members
6. What is the proper hand signal for 'stop' during crane-assisted tree removal? → One arm extended with a closed fist
7. What is the function of phloem in trees? → Transferring sugars and nutrients from leaves
8. What is the primary benefit of high Cation Exchange Capacity (CEC) in soil for tree health? → It enhances the soil's ability to retain and supply essential nutrient cations.
9. Which of the following correctly pairs a tree tissue with its primary function? → Cambium - a layer of cells responsible for secondary growth (thickening).
10. Fertilization of a newly planted tree is MOST appropriate: → After at least one full growing season of establishment
11. When performing aerial rescue of an injured arborist, what is the first priority? → Assess the scene for hazards and ensure rescuer safety before approaching the victim
12. Which tree growth form is MOST appropriate for planting in corridors beneath overhead utility lines? → Columnar or fastigiate
13. When selecting trees for a site with chronically compacted soils, which characteristic is MOST desirable? → Tolerance of reduced oxygen in the root zone
14. What diagnostic technique involves removing a section of bark to examine underlying wood for discoloration patterns? → Bark tracing
15. Anti-desiccant sprays are sometimes applied to newly planted trees primarily to: → Reduce water loss through transpiration from leaf surfaces
16. What is a common indicator of tree instability? → Visible cracks or cavities
17. When assessing a tree with codominant stems, what visual feature indicates the highest probability of failure at the union? → A visible crack or seam at the union combined with included bark between the stems
18. What is the impact of soil compaction on tree roots? → Reduces root oxygen and water absorption
19. What is the role of xylem in a tree? → Transferring water from roots to leaves
20. When assessing codominant stems, the presence of included bark in the union is a significant concern primarily because it: → Creates a weak attachment by preventing strong, interlocking wood tissue from forming.
21. When is the best time to prune most trees? → Late winter or early spring
22. Which factor is MOST important when determining the appropriate canopy spread of a tree selected for a residential planting? → Proximity to overhead utilities, structures, and property lines at maturity
23. When diagnosing a tree with progressive crown decline, yellowing foliage, and no visible trunk defects, what root-zone issue should be investigated first? → Girdling roots
24. The primary growth of a tree, which results in the elongation of its shoots and roots, originates from which type of meristematic tissue? → Apical Meristems
25. Which of the following best describes the primary safety function of the ground person responsible for managing the drop zone during tree removal operations? → To secure the area from entry by all unauthorized people and vehicles.
26. Which of the following is an example of 'target management' as a tree risk mitigation strategy? → Relocating a park bench from underneath a tree's dripline.
27. What is the proper way to cut a branch during pruning? → Cutting just outside the branch collar
28. What should be done to prevent tree damage when pruning after a storm? → Only remove broken or dangling branches
29. What role does organic matter play in soil management? → Enhances soil fertility
30. What is the recommended method for removing large branches? → Cutting in stages