Certified Arborist study guide
Certified Arborist · Work through your exam, one topic at a time.
The ISA Certified Arborist credential is a professional certification administered by the International Society of Arboriculture. ISA describes its credentials as a way to help consumers identify qualified, knowledgeable tree care professionals - which is why the designation is commonly referenced in hiring, contracting, and municipal tree care specifications. The Certified Arborist study guide has 8 sections and about 2,404 words.
01Tree Biology and Identification
All woody growth comes from meristems. Apical meristems extend shoots and roots; the vascular cambium produces xylem inward and phloem outward; the cork cambium makes periderm.
324 words, about 2 min02Soil and Water Management
Know texture (sand, silt, clay proportions), structure (aggregation), and pore space. A productive soil is roughly half solid and half pore space, with macropores for air movement and drainage and micropores for water retention.
293 words, about 1 min03Tree Nutrition and Fertilization
Know the macronutrients (N, P, K, Ca, Mg, S) and micronutrients (Fe, Mn, Zn, Cu, B, Mo, Cl, Ni). Mobility inside the plant drives symptom location: nitrogen, phosphorus, potassium, and magnesium are mobile, so deficiency appears first on older leaves; iron, calcium, boron, manganese, zinc, and copper are relatively immobile, so deficiency shows on new growth.
304 words, about 2 min04Tree Installation and Establishment
Recognize bareroot, container, and balled-and-burlapped stock, and the handling each requires. Root ball diameter generally scales with trunk caliper (roughly 10–12 inches of ball per inch of caliper for B&B stock).
305 words, about 2 min05Pruning and Tree Support Systems
Pruning serves structure, clearance, health, safety, and aesthetics. Learn the cut types - removal, thinning, reduction, and heading - and the anatomy that governs them.
307 words, about 2 min06Diagnosis and Plant Health Care
Diagnose in order: identify the plant, define what is abnormal, take a site and management history, then map the pattern of damage. Distribution matters - one tree, one species, one side, one soil type, or one irrigation zone all point to different causes.
281 words, about 1 min07Tree Risk Assessment and Management
Risk combines three factors: likelihood of failure, likelihood of impact on a target, and consequences of that impact. A target is a person or property that would be struck.
296 words, about 1 min08Safe Work Practices and Urban Forestry
Arboricultural operations follow ANSI Z133 and applicable OSHA rules. Personal protective equipment includes a helmet with chin strap, eye and hearing protection, chainsaw chaps, and sturdy boots.
294 words, about 1 min