Certified Arborist flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Vascular cambium function

The vascular cambium produces secondary xylem inward and secondary phloem outward, increasing trunk diameter; seasonal growth increments form the annual rings used to estimate tree age.

CODIT four walls

Compartmentalization of decay in trees proceeds through four walls: wall one plugs vessels, wall two forms tyloses and chemical boundaries, wall three limits radial spread, and wall four forms a barrier zone.

Opposite leaf arrangement

Opposite arrangement means leaves are paired at each node along the twig; maples, ashes, dogwoods, and buckeyes show this pattern, while most other trees are alternate.

Tension wood versus compression wood

In leaning angiosperms, tension wood forms on the upper side and pulls the stem upright; in leaning conifers, compression wood forms on the lower side and pushes the stem upward.

Field capacity definition

Field capacity is the water remaining in soil after free drainage from macropores, typically reached about two days after saturation, and it marks the upper limit of readily available water.

Soil bulk density limits

When mineral soil bulk density exceeds roughly 1.4 to 1.6 grams per cubic centimeter, pore space is reduced enough to restrict root growth, water infiltration, and gas exchange.

Soil pH and nutrient availability

Most trees take up nutrients best near pH 5.5 to 6.5; above pH 7, iron, manganese, zinc, and boron become less available, often causing interveinal chlorosis on new growth.

One inch irrigation volume

Applying one inch of water over one square foot requires about 0.62 gallons, so a 100 square foot root zone needs roughly 62 gallons to wet the soil to that depth.

Mobile versus immobile nutrients

Nitrogen, potassium, and magnesium are mobile in the plant, so deficiency appears first on older leaves; iron, calcium, and boron are immobile and show symptoms on new growth.

Fertilizer analysis N-P-K

Fertilizer analysis states the percentage by weight of nitrogen, available phosphate expressed as P2O5, and soluble potash expressed as K2O, always reported in that order.

Liebig's law of the minimum

Liebig's law states that plant growth is limited not by total resources but by whichever essential resource is in shortest supply relative to the plant's need.

Essential micronutrients for trees

The essential micronutrients are iron, manganese, zinc, copper, boron, molybdenum, chlorine, and nickel; they are required in very small amounts but can still limit growth.

Planting hole dimensions

A planting hole should be two to three times the width of the root ball but no deeper than the root ball, so the root flare sits at or slightly above grade.

Root flare placement

The root flare, where the first major roots diverge from the trunk, must sit at or slightly above the soil surface; burying it reduces oxygen and encourages girdling roots and decay.

Transplant establishment rate

A transplanted tree generally requires about one year per inch of trunk diameter to re-establish enough root growth for normal shoot extension, so aftercare continues for several years.

Bare-root planting timing

Bare-root nursery stock is planted during dormancy, when roots are fully moist and undisturbed; roots must be kept damp, shaded, and covered until planting.

Branch collar cut

A proper pruning cut is made just outside the branch bark ridge and branch collar, leaving the collar intact rather than cutting flush against the parent stem.

Three-cut pruning method

For large limbs, first make an undercut, then a top cut further out to leave a stub, then the final cut outside the branch collar to prevent bark tearing.

Live crown removal limit

Removing no more than about 25 percent of the live crown in a single season limits stress; heavier removal reduces carbohydrate production and can cause sprouting and decline.

Codominant stem risk

Codominant stems with a narrow angle and included bark form weak unions prone to splitting, because bark trapped between the stems prevents a strong shared connection.

Sign versus symptom

A sign is the visible structure of a pathogen or pest itself, such as conks, mycelium, or frass; a symptom is the plant's response, such as yellowing or wilting.

Biotic versus abiotic injury pattern

Abiotic injury usually appears uniformly on one species across a site and is symmetric on the plant; biotic injury is often random, progressive, and spreads from an epicenter.

Girdling root symptoms

Girdling roots often produce a declining, thin crown with no obvious aboveground cause, because roots encircle and compress the trunk, restricting water and carbohydrate movement.

IPM action threshold

Integrated pest management applies treatment only when a pest population is expected to exceed the level of injury that can be tolerated, rather than treating on a fixed calendar schedule.

Tree risk formula

Tree risk is calculated as the likelihood of failure multiplied by the likelihood of impacting a target, then multiplied by the consequences of that impact.

Critical root zone radius

For tree protection, the critical root zone is commonly defined as one to one and a half feet of radius per inch of trunk diameter, with a minimum radius of about ten feet.

Decay detection tools

Decay detection combines visual assessment with resistograph drilling, sonic tomography, and similar instruments; these estimate internal defect location but require trained interpretation.

Tree failure modes

The common failure modes of trees are uprooting with root plate lifting, stem or root failure at a defect, and branch failure at an included union or crack.

ANSI Z133 scope

ANSI Z133 sets the recognized safety requirements for arboricultural operations, including personal protective equipment, climbing, rigging, chippers, and electrical hazard approach distances.

Electrical minimum approach distance

Minimum approach distance from energized lines is 10 feet for lines up to 50 kilovolts, increasing with voltage; only qualified line-clearance arborists work within that distance.

Chipper infeed safety

Never place hands or feet in a chipper infeed; feed material from the side of the chute and keep the feed area clear so operators cannot be drawn into the rollers.

Drop zone requirement

A drop zone is the area beneath aerial work kept clear of all personnel except the climber, protecting ground workers from falling limbs, tools, and debris.