Certified Arborist cheat sheet

Apical meristems at shoot and root tips produce primary growth (extension in length); the vascular cambium produces secondary xylem inward and phloem outward, adding diameter.

Xylem transports water and dissolved minerals upward from the roots; phloem translocates photosynthate from sources to sinks, with direction varying by season and demand.

CODIT walls: wall 1 = vessel plugging, wall 2 = tyloses and chemical boundaries, wall 3 = ray parenchyma restricting radial spread, wall 4 = a new suberized barrier zone.

Compression wood forms on the underside of leaning conifers and pushes the stem upward; tension wood forms on the upper side of leaning broadleaf trees and pulls it upright.

Opposite leaf arrangement occurs in maples (Acer), ashes (Fraxinus), dogwoods (Cornus), and buckeyes (Aesculus); alternate arrangement is the most common condition.

On a compound leaf, axillary buds occur at the base of the entire leaf, not at the base of individual leaflets; this distinguishes leaflets from twigs.

Monocots such as palms have scattered vascular bundles and no vascular cambium, so they do not produce annual rings or true secondary growth.

Roughly 60-80% of fine absorbing roots occupy the top 30 cm (12 in) of soil, and roots commonly extend 2-3 times the canopy radius.

Soil texture is classified by percent sand, silt, and clay; a loam is approximately 40% sand, 40% silt, and 20% clay.

Available water capacity lies between field capacity and permanent wilting point; micropores retain this water while macropores drain freely by gravity.

Cation exchange capacity rises with clay content and organic matter, increasing the soil's ability to hold nutrients such as calcium, magnesium, and potassium.

Most trees grow best between pH 5.5 and 6.5; above pH 7, iron, manganese, zinc, and boron availability declines sharply.

Mineral soil bulk density above about 1.4-1.6 g/cm3 reduces pore space enough to restrict root penetration, drainage, and gas exchange.

Root respiration requires oxygen; below roughly 10% soil oxygen, or under prolonged saturation, water and nutrient uptake decline and fine roots die.

One inch of irrigation over 1 sq ft equals about 0.62 gallons, so a 100 sq ft root zone needs roughly 62 gallons to receive one inch.

Apply mulch 2-4 inches deep and pull it a few inches back from the trunk; deeper layers reduce oxygen diffusion into the root zone.

Seventeen elements are essential: C, H, O from air and water; N, P, K, Ca, Mg, S from soil in larger amounts; Fe, Mn, Zn, Cu, B, Mo, Cl, Ni in trace amounts.

Liebig's law of the minimum: growth is governed by whichever essential resource is in shortest supply relative to need, not by total resource abundance.

Mobile nutrients (N, P, K, Mg) show deficiency symptoms on older leaves first; immobile nutrients (Fe, Ca, B, Mn) show symptoms on new growth first.

Fertilizer analysis N-P-K reports percent nitrogen, percent available phosphate as P2O5, and percent soluble potash as K2O, always in that order.

A common landscape nitrogen rate is 1-3 lb of actual N per 1,000 sq ft per year, applied within the root zone rather than near the trunk.

Iron chlorosis at high soil pH is addressed by acidifying soil, applying chelated iron, or using trunk/foliar treatments; adding phosphate worsens it.

Avoid high-nitrogen fertilization of newly planted trees during the first growing season, because it pushes shoot growth ahead of root establishment.

Foliar feeding corrects a deficiency quickly but temporarily; it supplements, and does not replace, correction of the underlying soil problem.

Mycorrhizal fungi improve phosphorus and water uptake; high soil phosphorus levels can suppress colonization.

Dig the planting hole 2-3 times the width of the root ball but no deeper than the root ball; set the root flare at or slightly above grade.

Remove twine, burlap, and wire basket from the top half of the root ball, and remove any material encircling the trunk entirely.

On container-grown stock, cut or straighten circling and kinked roots at the top and sides of the root mass before backfilling.

Deep planting buries the root flare and leads to girdling roots, stem decay, and chronic decline; verify flare depth after settling and irrigation.

Backfill with the soil removed from the hole; if soil amendment is warranted, amend the entire planting area rather than the hole alone.

Water immediately after planting to settle soil, then supply about 1 inch per week through the first 2-3 growing seasons when rainfall is inadequate.

Establishment takes roughly one year per inch of trunk diameter, during which irrigation and weed control determine survival and growth.

Stake only when the root ball or stem requires stabilization, use flexible ties with slack, and remove supports after one to two growing seasons.

Bare-root stock must be planted during dormancy with roots kept moist, shaded, and never allowed to desiccate.

Final cuts are made just outside the branch collar and branch bark ridge; flush cuts and stub cuts both remove or damage the tree's defense zone.

Use the three-cut method on limbs too large to support: an undercut, a top cut leaving a stub, then the final cut outside the collar to avoid bark tearing.

Remove no more than about 25% of the live crown in a single season to limit carbohydrate loss and stress.

When reducing a limb, cut back to a lateral at least one-third the diameter of the removed portion; heading cuts to arbitrary points trigger prolific sprouting.

Topping, lion's tailing, and tipping are disallowed practices under ANSI A300, the standard for tree pruning.

Dead, diseased, and broken wood may be removed at any time; live pruning is best scheduled in late dormant season for most species.

Avoid wounding oaks during spring where oak wilt occurs, because sap-feeding beetles carry the fungus to fresh wounds.

Static support systems limit movement at weak unions; dynamic systems allow motion. Both are designed and installed per ANSI A300 Part 3.

Wound dressings are not recommended; they do not prevent decay or accelerate wound closure and may trap moisture.

Diagnostic order: identify the plant, examine the site and soil, gather management history, characterize the pattern and distribution of injury, then look for signs.

Signs are the pest or pathogen itself (conks, mycelium, frass, egg masses); symptoms are the plant's response (chlorosis, wilting, cankers, dieback).

Abiotic injury tends to be uniform across one species on a site and symmetric on the plant; biotic injury is often patchy, progressive, and spreads from an epicenter.

Root and vascular problems appear as crown dieback, reduced leaf size, and thin foliage, typically without lesions on the main stem.

Growth-regulator herbicide injury such as 2,4-D produces leaf cupping, strapping, and twisted, epinastic growth on broadleaf trees.

Koch's postulates confirm a pathogen: isolate it, culture it, inoculate a healthy host, and recover the same organism from the resulting symptoms.

Soil tests report pH and extractable nutrients; tissue tests compare foliar nutrient concentrations against established sufficiency ranges.

Integrated pest management combines monitoring, action thresholds, and cultural, biological, and chemical controls in that order of preference.

Risk = likelihood of failure × likelihood of impact on a target × consequences of that impact; removing any factor removes the risk.

Tree risk assessment levels: limited (ground-based visual), basic (360-degree inspection with simple tools), and advanced (aerial inspection, decay detection).

A hazard exists only when a defective tree can reach a target; with no target there is no risk, only a maintenance concern.

Visual tree assessment looks for cracks, conks, cavities, included bark, root plate lifting, soil mounding, and recent changes in lean.

Common failure modes are uprooting, stem or root failure at a defect, and branch failure at an occluded union or crack.

A resistograph and sonic tomography estimate the location and extent of internal decay, but results must be interpreted with species and site context.

Mitigation options include moving or removing the target, pruning, installing support systems, reducing load, removing the tree, or monitoring.

Document findings and set a re-inspection interval based on defect severity, target value, and the rate of change expected.

ANSI Z133 establishes safety requirements for arboricultural operations, covering personal protective equipment, climbing, rigging, chippers, and electrical hazards.

Minimum approach distance to energized lines is 10 ft for lines up to 50 kV, increasing with voltage; only qualified line-clearance arborists work closer.

Required PPE includes a helmet with chin strap, eye protection, hearing protection, gloves, and chainsaw-protective chaps.

Climbers maintain two points of attachment, and the tie-in point must be in sound wood capable of supporting the intended load.

Chainsaw kickback is managed with the chain brake, a firm two-handed grip, and by avoiding the upper tip quadrant of the bar.

Never place hands or feet in a chipper infeed; feed from the side of the chute and keep the feed area clear of bystanders.

Life-support rigging components are rated with a safety factor, commonly about 10:1 for climbing systems.

The critical root zone for construction protection is usually 1 to 1.5 ft of radius per inch of DBH, with a 10 ft minimum, enclosed by fencing.

Urban forest inventories support canopy-cover goals and management plans; tools such as i-Tree quantify stormwater, energy, and air-quality benefits.