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Certified Arborist exam prep

48 video lessons across all 10 domains of the ISA Certified Arborist exam, then 3 full mock exams to check you're ready.

48 lessons125 minutes of video600 mock exam questions12 months' access
Photo: TS Eriksson, CC BY 3.0

Every lesson has a narrated video, five exam-style questions, a sorting drill, flashcards and a printable study sheet. The lessons follow ISA's examination outline domain by domain.

Domain 1: Tree Biology

11% of the exam, about 22 of the 200 questions.

  1. 1Roots, trunk, branches and leaves: tree anatomyWhat each part of a tree does, from absorbing roots to leaves, and the tissues inside the trunk that the exam expects you to name.
  2. 2Photosynthesis, respiration and energy storageHow a tree makes sugar, spends it and stores it, and why energy reserves shape when and how hard you prune.
  3. 3Water movement: uptake, transport and transpirationHow water gets from the soil to the leaves, the structures it moves through, and what happens when it runs short.
  4. 4CODIT and wood's response to stressHow trees wall off decay after wounding, how wood grows in response to load, and how that shapes management by developmental stage.Free lesson
  5. 5Growth, reproduction, life cycle and declineHow trees grow in height and girth, reproduce and propagate, move through the seasons and life stages, and how they decline and die.

Domain 2: Tree Identification and Selection

9% of the exam, about 18 of the 200 questions.

  1. 6Why identification matters: names and classificationWhy accurate identification underpins diagnosis and care, how trees are classified, and how to write scientific names correctly in reports.
  2. 7Identifying trees by leaves, twigs and budsThe parts of a twig and a leaf, leaf types, arrangements and margins, and how to collect samples that make identification possible.
  3. 8Flowers, fruits, form and ID toolsFlower and fruit types, tree forms and silhouettes, how tropical and desert trees are adapted, and how to use keys, guides and apps.
  4. 9Right tree, right place: selecting species for a siteAssessing a planting site, matching species characteristics to it, keeping the urban forest diverse, and explaining your choice to others.

Domain 3: Soil Management

7% of the exam, about 14 of the 200 questions.

  1. 10Soil formation, horizons, texture and structureHow soil forms, the horizons in a profile, texture, structure, pore space and bulk density, and how to assess them on site.
  2. 11Soil chemistry and biology: pH, CEC and mycorrhizaeSoil pH and nutrient availability, cation exchange and buffering, the living soil around roots, urban soils, and where roots actually grow.
  3. 12Soil water, drainage and irrigationHow water behaves in soil, why layers stop drainage, how to build a water budget, and how to water trees effectively.
  4. 13Soil testing, nutrition, fertilization and remediationSampling and interpreting soil tests, tree nutrients, fertilizer types and application, mulch and amendments, and fixing urban soils.

Domain 4: Installation and Establishment

9% of the exam, about 18 of the 200 questions.

  1. 14Nursery stock: types, quality and inspectionThe main types of nursery stock, their pros and cons, what a good tree looks like, how to inspect roots before buying, and safe handling.
  2. 15Planting a tree to standardWhen to plant, preparing the site and hole, setting the depth, removing packaging, correcting roots, backfilling, watering and mulching.
  3. 16Transplanting established treesAssessing whether a tree can be moved, preparing roots in advance, moving and replanting it, and the care it needs to re-establish.
  4. 17Aftercare: water, mulch, support and young-tree pruningWatering, mulching and supporting newly planted trees, spotting planting mistakes, pruning young trees for structure, and involving the community.

Domain 5: Pruning

14% of the exam, about 28 of the 200 questions.

  1. 18Why prune: objectives, standards and outcomesSetting pruning objectives, the standards that govern pruning, timing and dose, what pruning can and can't achieve, and explaining it to clients.
  2. 19Branch unions, the branch collar and wound responseHow branches attach, why codominant stems and included bark are weak, where to place a cut, and how trees respond to pruning wounds.
  3. 20Types of pruning cut and how to sequence themBranch removal, reduction, heading and shearing cuts, when each is appropriate, and how to sequence cuts to avoid tearing bark.Free lesson
  4. 21Pruning systems: natural, pollard, espalier and fruitThe main pruning systems, from natural form to pollarding, espalier and fruit production, and how to write pruning objectives and specifications.
  5. 22Harmful pruning: topping, lion-tailing, flush cuts and dressingsThe pruning practices that harm trees, what they do to health and structure, and how to explain why they should be avoided.
  6. 23Root pruning and utility pruningPruning roots without destabilizing the tree, pruning near power lines, and the safety rules for working near electrical systems.
  7. 24Pruning tools: selection, safety and disinfectionHand tools, saws, pole tools and chainsaws, choosing the right tool, keeping it sharp and clean, and disinfecting against disease spread.

Domain 6: Diagnosis and Treatment

9% of the exam, about 18 of the 200 questions.

  1. 25Diagnosis: signs, symptoms, biotic and abioticThe difference between signs and symptoms, living and non-living causes, and a step-by-step way to diagnose a tree problem.
  2. 26Insects, mites and other biotic agentsHow insects and mites damage trees, their life cycles, pests that carry diseases, nematodes and animals, and how to keep up with new regional threats.
  3. 27Tree diseases and abiotic disordersThe disease triangle and cycle, fungal and bacterial diseases, and the abiotic disorders that stress trees most often.
  4. 28Plant health care and integrated pest managementPrevention, early detection and treatment in PHC, the steps of IPM, stress and compounding factors, pesticide rules, and managing a PHC plan.

Domain 7: Trees and Construction

9% of the exam, about 18 of the 200 questions.

  1. 29Construction impacts on roots, trunks and crownsHow construction damages roots, trunks and crowns, why trees often decline years later, and what that means for stability.
  2. 30Tree protection zones and critical root zonesThe standards for trees and construction, how to size a tree protection zone, the critical root zone, and the methods that protect roots, trunks and crowns.
  3. 31Tree protection plans through the construction phasesReading site plans, the phases of construction, who is responsible for what, coordinating with contractors, and checking the plan works.
  4. 32Treating construction-damaged treesAssessing damage and risk after construction, deciding when to remove and replace, and the treatments that help a damaged tree recover.

Domain 8: Tree Risk Management

11% of the exam, about 22 of the 200 questions.

  1. 33Tree risk: roles, responsibilities and communicationWho does what in tree risk management, how risk is defined, and how to communicate risk clearly to people with very different backgrounds.
  2. 34What can fail: whole trees, parts and other risksWhole-tree versus part failure, tree stability, and the other risks trees can pose, from tripping to power lines and allergens.
  3. 35Levels of assessment, targets and site factorsThe three levels of tree risk assessment and when to use each, how to analyze targets and occupancy, and the site factors that affect risk.
  4. 36Defects and conditions that raise the likelihood of failureThe tree defects and conditions that make failure more likely, how to recognize them from the ground, and how to judge their significance.Free lesson
  5. 37Mitigating risk and setting inspection intervalsTree-based and target-based ways to reduce risk, choosing and recommending mitigation, residual risk, and deciding when to inspect again.

Domain 9: Safe Work Practices

15% of the exam, about 30 of the 200 questions.

  1. 38Safety standards, work planning and the job briefingThe standards and laws behind safe tree work, planning the job, securing the work zone, running a job briefing, and why training matters.
  2. 39Hazard assessment: the tree, the site and trafficInspecting a tree before work, judging whether it can take the forces you'll apply, checking the surrounding area, and managing traffic.
  3. 40Worker hazards: wildlife, plants, ergonomics, fire and fuelHazards from insects, animals and plants, protecting your body from strain, fire safety with fuel and tools, command-and-response signals, and storing hazardous materials.
  4. 41Electrical hazards and minimum approach distancesHow the power system is laid out, how electricity injures, direct and indirect contact, the Z133 electrical qualification levels, and minimum approach distances.
  5. 42PPE and climbing equipmentPersonal protective equipment from head to foot, climbing saddles, connectors, lanyards and friction devices, and how to inspect and maintain it all.
  6. 43Climbing systems and aerial rescueClimbing rope systems, knots and hitches, tying in and ascending, working and descending safely, and preparing for an aerial rescue.
  7. 44Tools, chainsaws, chippers, aerial lifts and cranesChainsaw safety features and kickback, chippers and stump grinders, aerial lifts, cranes and large vehicles, and inspecting equipment before use.
  8. 45Rigging, felling, dismantling and emergenciesRigging hardware and techniques, anchor strength, felling and dismantling cuts, removal hazards such as barber chairs, work positioning, and emergency response.

Domain 10: Urban Forestry

6% of the exam, about 12 of the 200 questions.

  1. 46The benefits and value of urban treesThe environmental, economic, social, health and aesthetic benefits of trees, benefit-cost ratios, tree appraisal, and value calculators.
  2. 47Tree laws, ordinances and permitsTree ordinances and preservation orders, permits and licenses, wildlife and habitat laws, property and zoning rules, and keeping your references current.
  3. 48Urban forest management plans and public outreachTree inventories, canopy goals and planting plans, maintenance cycles, diversity, invasive species and pests, sustainability, and engaging the community.
Questions

Before you buy

Is ArboristPass an ISA course?

No. ArboristPass is an independent exam-prep course. It isn't affiliated with, endorsed by or approved by the International Society of Arboriculture (ISA), which runs the Certified Arborist exam.

Who is it for?

Tree care professionals preparing for the ISA Certified Arborist exam. ISA requires three years of full-time experience in arboriculture, or a relevant degree plus experience, before you can sit the exam; check the current rules on isa-arbor.com.

What does the course cover?

All 10 domains in ISA's examination outline, from tree biology to urban forestry, in 48 short video lessons. Each domain gets roughly as many lessons as its share of the exam, so pruning and safe work practices get the most time.

Are the mock exams like the real exam?

They follow the published format: 200 four-option multiple-choice questions in 3.5 hours, weighted by domain, with 76% needed to pass. The real exam includes 20 unscored trial questions; ours score all 200. The questions are our own, written for this course, not copied from ISA's exam.

Is the content up to date?

Safety content follows ANSI Z133-2026. The exam outline dates from 2022, so exam questions may still use values from the 2017 standard. Where values changed, such as climbing line strength, the lessons give both.

How long do I have access?

12 months from purchase, on any phone, tablet or computer. Study sheets are PDF files you can print and keep.

Can I get a refund?

Yes. ArboristPass has a 14-day money-back guarantee: if it isn't right for you, ask within 14 days of purchase and we'll refund you in full, as long as you've completed no more than 5 lessons and haven't started a mock exam.