ISA Arborist Certification Glossary Exam
Questions and Answers 100% Verified
abiotic: - CORRECT ANSWER-pertaining to the nonliving parts of an ecosystem, such
as soil particles, bedrock, air, water.
abscisic acid (ABA): - CORRECT ANSWER-a plant hormone that stimulates stomatal
closure and promotes seed and bud dormancy.
abscission zone: - CORRECT ANSWER-a wall of cells at the base of a petiole, that
allows the leaf to separate from the stem.
acceptable risk: - CORRECT ANSWER-the amount of risk that an owner is willing to
accept before tree failure.
accessibility: - CORRECT ANSWER-the establishment of a location used to enter a
site.
acidic soil: - CORRECT ANSWER-having a pH les than 7.0, in contrast with alkaline
which has a pH that is higher than 7.0.
actinomycetes: - CORRECT ANSWER-microorganisms that have some characteristics
of fungi and bacteria. Soil actinomycetes are very tolerant of water stress and contribute
through their actions to that "good earth" aroma after a rain.
action: - CORRECT ANSWER-the number of distinct motions for the carabineers and
snaps gate to be opened.
action threshold: - CORRECT ANSWER-the point at which a pest requires the
implementation of a management tactic or control.
acute crotches: - CORRECT ANSWER-stronger and wider than a co-dominant crotch,
they are not likely to be a branch that will fail in high winds and are considered
desirable.
adaptive growth: - CORRECT ANSWER-an increase in wood production in localized
areas on a tree, in response to a decrease in wood strength or external loading to
maintain an even distribution of forces across the structure.
drip line - CORRECT ANSWER-a boundary on the ground delineated by the branch
spread of a single tree or group of trees.
,adsorption: - CORRECT ANSWER-adhesion on contact of molecules to the surface of
solids or liquids with which they are in contact.
advanced assessment: - CORRECT ANSWER-an assessment performed to provide
detailed information about specific tree parts, defects or site conditions.
adventitious/epicormic growth: - CORRECT ANSWER-new growth arising directly from
dormant or new buds on main branches, stems, or trunks often in response to moisture
and light that has no connection to apical meristems.
adventitious root: - CORRECT ANSWER-a root arising from parts of the root or the
stem, often in response to moisture and darkness that has no connection to apical
meristems.
aeration: - CORRECT ANSWER-the provision of air to the soil to alleviate soil
compaction.
aerial lift device: - CORRECT ANSWER-a truck with booms and a bucket, for elevating
a worker to a tree's crown; may also be mounted on a self-propelled machine known as
a mini-lift.
aerial rescue: - CORRECT ANSWER-a method of bringing an injured worker down from
a tree.
aerial roots: - CORRECT ANSWER-roots that grow from stems toward the soil with the
capacity to become prop roots when they anchor in the soil.
aerobic microorganisms: - CORRECT ANSWER-these microbes require free, gaseous
oxygen for growth.
aggregate: - CORRECT ANSWER-soil such as sand, silt, or clay, a cluster of soil
particles and organic matter, bonded together by exudates from microorganisms. It is
often used under paved surfaces, as backfill.
agroforestry or agro-sylviculture: - CORRECT ANSWER-is a land use management
system in which trees or shrubs are grown around or among crops or pastureland.
Air Spade™: - CORRECT ANSWER-the commonly used trade name for an air tool.
air terminal: - CORRECT ANSWER-the uppermost point of a lightning protection system
in a tree. It is usually made of copper.
air tool: - CORRECT ANSWER-also called air excavation device, a device that uses a
jet of compressed air to excavate soil within the root zone of trees and minimize
damage to tree roots.
,alkaline soil: - CORRECT ANSWER-having a pH greater than 7.0, in contrast with
acidic soil which has a pH lower than 7.0.
alkaloids: - CORRECT ANSWER-substances that are produced by trees and contain
nitrogen and are used by humans for medicines.
allée: - CORRECT ANSWER-two parallel rows of trees, usually of the same species,
form, and age, often having canopies that have grown together.
allelopathy: - CORRECT ANSWER-the production of substances by one tree that
adversely affect other trees nearby. Root exudates from some trees can kill or stall
growth of many soil organisms.
alternate leaves: - CORRECT ANSWER-occur when there is one bud or leaf at a node.
amylase: - CORRECT ANSWER-an enzyme that can change the starch chains back to
glucose molecules.
anaerobic microorganisms: - CORRECT ANSWER-these microbes live in the absence
of free oxygen.
amon-eye nut: - CORRECT ANSWER-drop-forged eye nut is used to fasten through-
hardware anchor(s), used when cabling trees.
anchor: - CORRECT ANSWER-the hardware installed to affix and/or terminate a cable
or guy to the tree, ground, or other device.
anchor-tree: - CORRECT ANSWER-a tree used to provide supplemental support in a
guying installation.
angiosperms: - CORRECT ANSWER-hardwood trees that have covered seeds such as
oaks and maples. The seed is born within an ovary.
anions: - CORRECT ANSWER-negatively charged atoms or molecules in fertilizer that
become available to the plant in water.
ANSI: - CORRECT ANSWER-the American National Standards Institute.
ANSI A300: - CORRECT ANSWER-the performance parameters established by
industry consensus as a rule for the measure of extent, quality, quantity, value, or
weight used to write specifications.
ANSI Z60.1: - CORRECT ANSWER-the American Standard for Nursery Stock, 2014
edition.
, ANSI Z133: - CORRECT ANSWER-the Safety Standard that provides the most current
criteria in the United States for arborists and other workers engaged in arboricultural
operations.
anther: - CORRECT ANSWER-the pollen producing part of a flower.
anthocyanin: - CORRECT ANSWER-a chemical that gives the red pigments to leaves
and other plant organs.
antitranspirant: - CORRECT ANSWER-a substance applied to the foliage of plants to
reduce water loss.
anvil-type pruning tool: - CORRECT ANSWER-a pruning tool that has a sharp straight
blade that cuts against a flat non-cutting surface.
apical dominance: - CORRECT ANSWER-the inhibition of growth of lateral buds by the
terminal or apical bud.
apical meristem: - CORRECT ANSWER-meristems increase the length of stems and
roots, and produce flowers.
apoplast: - CORRECT ANSWER-the framework of non-living cells and cell walls in
wood and bark. The apoplast stores bound water, which does not flow.
appraisal: - CORRECT ANSWER-placing a monetary value on a tree.
approach distances: - CORRECT ANSWER-the minimum distances between energized
conductors and personnel.
arboriculture: - CORRECT ANSWER-the art, science, technology, and business of
commercial, public, and utility tree care. Arboriculture focus is on the tree while the
focus of forestry is on all trees.
arborist: - CORRECT ANSWER-an individual engaged in the profession of arboriculture
who, through experience, education, and training, possesses the competence to
perform the management of trees and other woody plants.
arborist trainee: - CORRECT ANSWER-an individual undergoing on-the-job training to
obtain the experience required to manage trees and woody plants. Such trainees shall
be under the supervision of an arborist.
arbuscular mycorrhizae: - CORRECT ANSWER-commonly called endomycorrhizae
infects the internal tree root cells and are most common in deciduous forests.
