ISA Arborist Certification Glossary
Exam with Accurate Solutions
abiotic: - ANS-pertaining to the nonliving parts of an ecosystem, such as soil particles,
bedrock, air, water.
abscisic acid (ABA): - ANS-a plant hormone that stimulates stomatal closure and
promotes seed and bud dormancy.
abscission zone: - ANS-a wall of cells at the base of a petiole, that allows the leaf to
separate from the stem.
acceptable risk: - ANS-the amount of risk that an owner is willing to accept before tree
failure.
accessibility: - ANS-the establishment of a location used to enter a site.
acidic soil: - ANS-having a pH les than 7.0, in contrast with alkaline which has a pH that
is higher than 7.0.
actinomycetes: - ANS-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: - ANS-the number of distinct motions for the carabineers and snaps gate to be
opened.
action threshold: - ANS-the point at which a pest requires the implementation of a
management tactic or control.
acute crotches: - ANS-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: - ANS-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 - ANS-a boundary on the ground delineated by the branch spread of a single
tree or group of trees.
,adsorption: - ANS-adhesion on contact of molecules to the surface of solids or liquids
with which they are in contact.
advanced assessment: - ANS-an assessment performed to provide detailed information
about specific tree parts, defects or site conditions.
adventitious/epicormic growth: - ANS-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: - ANS-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: - ANS-the provision of air to the soil to alleviate soil compaction.
aerial lift device: - ANS-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: - ANS-a method of bringing an injured worker down from a tree.
aerial roots: - ANS-roots that grow from stems toward the soil with the capacity to
become prop roots when they anchor in the soil.
aerobic microorganisms: - ANS-these microbes require free, gaseous oxygen for
growth.
aggregate: - ANS-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: - ANS-is a land use management system in which
trees or shrubs are grown around or among crops or pastureland.
Air Spade™: - ANS-the commonly used trade name for an air tool.
air terminal: - ANS-the uppermost point of a lightning protection system in a tree. It is
usually made of copper.
air tool: - ANS-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: - ANS-having a pH greater than 7.0, in contrast with acidic soil which has a
pH lower than 7.0.
alkaloids: - ANS-substances that are produced by trees and contain nitrogen and are
used by humans for medicines.
,allée: - ANS-two parallel rows of trees, usually of the same species, form, and age,
often having canopies that have grown together.
allelopathy: - ANS-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: - ANS-occur when there is one bud or leaf at a node.
amylase: - ANS-an enzyme that can change the starch chains back to glucose
molecules.
anaerobic microorganisms: - ANS-these microbes live in the absence of free oxygen.
amon-eye nut: - ANS-drop-forged eye nut is used to fasten through-hardware anchor(s),
used when cabling trees.
anchor: - ANS-the hardware installed to affix and/or terminate a cable or guy to the tree,
ground, or other device.
anchor-tree: - ANS-a tree used to provide supplemental support in a guying installation.
angiosperms: - ANS-hardwood trees that have covered seeds such as oaks and
maples. The seed is born within an ovary.
anions: - ANS-negatively charged atoms or molecules in fertilizer that become available
to the plant in water.
ANSI: - ANS-the American National Standards Institute.
ANSI A300: - ANS-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: - ANS-the American Standard for Nursery Stock, 2014 edition.
ANSI Z133: - ANS-the Safety Standard that provides the most current criteria in the
United States for arborists and other workers engaged in arboricultural operations.
anther: - ANS-the pollen producing part of a flower.
anthocyanin: - ANS-a chemical that gives the red pigments to leaves and other plant
organs.
antitranspirant: - ANS-a substance applied to the foliage of plants to reduce water loss.
, anvil-type pruning tool: - ANS-a pruning tool that has a sharp straight blade that cuts
against a flat non-cutting surface.
apical dominance: - ANS-the inhibition of growth of lateral buds by the terminal or apical
bud.
apical meristem: - ANS-meristems increase the length of stems and roots, and produce
flowers.
apoplast: - ANS-the framework of non-living cells and cell walls in wood and bark. The
apoplast stores bound water, which does not flow.
appraisal: - ANS-placing a monetary value on a tree.
approach distances: - ANS-the minimum distances between energized conductors and
personnel.
arboriculture: - ANS-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: - ANS-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: - ANS-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: - ANS-commonly called endomycorrhizae infects the internal
tree root cells and are most common in deciduous forests.
armillaria root disease: - ANS-cause death to trees under all types of stress by reducing
absorption and translocation of water and minerals from the soil to the tree.
arthropods: - ANS-microscopic insects and mites that are vital in processing soil organic
matter and mineralizing detritus.
ascender: - ANS-attached to the rope, this piece of equipment will grip in one direction
(down) and slide in the other (up) allowing the climber to ascend up the rope in contrast
with descender.
auger: - ANS-a tool that bores holes in wood.
auxin: - ANS-a tree growth regulator that controls cell elongation.
Exam with Accurate Solutions
abiotic: - ANS-pertaining to the nonliving parts of an ecosystem, such as soil particles,
bedrock, air, water.
abscisic acid (ABA): - ANS-a plant hormone that stimulates stomatal closure and
promotes seed and bud dormancy.
abscission zone: - ANS-a wall of cells at the base of a petiole, that allows the leaf to
separate from the stem.
acceptable risk: - ANS-the amount of risk that an owner is willing to accept before tree
failure.
accessibility: - ANS-the establishment of a location used to enter a site.
acidic soil: - ANS-having a pH les than 7.0, in contrast with alkaline which has a pH that
is higher than 7.0.
actinomycetes: - ANS-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: - ANS-the number of distinct motions for the carabineers and snaps gate to be
opened.
action threshold: - ANS-the point at which a pest requires the implementation of a
management tactic or control.
acute crotches: - ANS-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: - ANS-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 - ANS-a boundary on the ground delineated by the branch spread of a single
tree or group of trees.
,adsorption: - ANS-adhesion on contact of molecules to the surface of solids or liquids
with which they are in contact.
advanced assessment: - ANS-an assessment performed to provide detailed information
about specific tree parts, defects or site conditions.
adventitious/epicormic growth: - ANS-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: - ANS-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: - ANS-the provision of air to the soil to alleviate soil compaction.
aerial lift device: - ANS-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: - ANS-a method of bringing an injured worker down from a tree.
aerial roots: - ANS-roots that grow from stems toward the soil with the capacity to
become prop roots when they anchor in the soil.
aerobic microorganisms: - ANS-these microbes require free, gaseous oxygen for
growth.
aggregate: - ANS-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: - ANS-is a land use management system in which
trees or shrubs are grown around or among crops or pastureland.
Air Spade™: - ANS-the commonly used trade name for an air tool.
air terminal: - ANS-the uppermost point of a lightning protection system in a tree. It is
usually made of copper.
air tool: - ANS-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: - ANS-having a pH greater than 7.0, in contrast with acidic soil which has a
pH lower than 7.0.
alkaloids: - ANS-substances that are produced by trees and contain nitrogen and are
used by humans for medicines.
,allée: - ANS-two parallel rows of trees, usually of the same species, form, and age,
often having canopies that have grown together.
allelopathy: - ANS-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: - ANS-occur when there is one bud or leaf at a node.
amylase: - ANS-an enzyme that can change the starch chains back to glucose
molecules.
anaerobic microorganisms: - ANS-these microbes live in the absence of free oxygen.
amon-eye nut: - ANS-drop-forged eye nut is used to fasten through-hardware anchor(s),
used when cabling trees.
anchor: - ANS-the hardware installed to affix and/or terminate a cable or guy to the tree,
ground, or other device.
anchor-tree: - ANS-a tree used to provide supplemental support in a guying installation.
angiosperms: - ANS-hardwood trees that have covered seeds such as oaks and
maples. The seed is born within an ovary.
anions: - ANS-negatively charged atoms or molecules in fertilizer that become available
to the plant in water.
ANSI: - ANS-the American National Standards Institute.
ANSI A300: - ANS-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: - ANS-the American Standard for Nursery Stock, 2014 edition.
ANSI Z133: - ANS-the Safety Standard that provides the most current criteria in the
United States for arborists and other workers engaged in arboricultural operations.
anther: - ANS-the pollen producing part of a flower.
anthocyanin: - ANS-a chemical that gives the red pigments to leaves and other plant
organs.
antitranspirant: - ANS-a substance applied to the foliage of plants to reduce water loss.
, anvil-type pruning tool: - ANS-a pruning tool that has a sharp straight blade that cuts
against a flat non-cutting surface.
apical dominance: - ANS-the inhibition of growth of lateral buds by the terminal or apical
bud.
apical meristem: - ANS-meristems increase the length of stems and roots, and produce
flowers.
apoplast: - ANS-the framework of non-living cells and cell walls in wood and bark. The
apoplast stores bound water, which does not flow.
appraisal: - ANS-placing a monetary value on a tree.
approach distances: - ANS-the minimum distances between energized conductors and
personnel.
arboriculture: - ANS-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: - ANS-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: - ANS-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: - ANS-commonly called endomycorrhizae infects the internal
tree root cells and are most common in deciduous forests.
armillaria root disease: - ANS-cause death to trees under all types of stress by reducing
absorption and translocation of water and minerals from the soil to the tree.
arthropods: - ANS-microscopic insects and mites that are vital in processing soil organic
matter and mineralizing detritus.
ascender: - ANS-attached to the rope, this piece of equipment will grip in one direction
(down) and slide in the other (up) allowing the climber to ascend up the rope in contrast
with descender.
auger: - ANS-a tool that bores holes in wood.
auxin: - ANS-a tree growth regulator that controls cell elongation.
