ISA Arborist Certification Questions with
Verified Correct Answers
abiotic:
pertaining to the nonliving parts of an ecosystem, such as soil particles, bedrock, air, water.
abscisic acid (ABA):
a plant hormone that stimulates stomatal closure and promotes seed and bud dormancy.
abscission zone:
a wall of cells at the base of a petiole, that allows the leaf to separate from the stem.
acceptable risk:
the amount of risk that an owner is willing to accept before tree failure.
accessibility:
the establishment of a location used to enter a site.
acidic soil:
having a pH les than 7.0, in contrast with alkaline which has a pH that is higher than 7.0.
actinomycetes:
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:
the number of distinct motions for the carabineers and snaps gate to be opened.
,action threshold:
the point at which a pest requires the implementation of a management tactic or control.
acute crotches:
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:
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
a boundary on the ground delineated by the branch spread of a single tree or group of trees.
adsorption:
adhesion on contact of molecules to the surface of solids or liquids with which they are in
contact.
advanced assessment:
an assessment performed to provide detailed information about specific tree parts, defects or
site conditions.
adventitious/epicormic growth:
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:
, 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:
the provision of air to the soil to alleviate soil compaction.
aerial lift device:
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:
a method of bringing an injured worker down from a tree.
aerial roots:
roots that grow from stems toward the soil with the capacity to become prop roots when they
anchor in the soil.
aerobic microorganisms:
these microbes require free, gaseous oxygen for growth.
aggregate:
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:
is a land use management system in which trees or shrubs are grown around or among crops
or pastureland.
Air Spade™:
Verified Correct Answers
abiotic:
pertaining to the nonliving parts of an ecosystem, such as soil particles, bedrock, air, water.
abscisic acid (ABA):
a plant hormone that stimulates stomatal closure and promotes seed and bud dormancy.
abscission zone:
a wall of cells at the base of a petiole, that allows the leaf to separate from the stem.
acceptable risk:
the amount of risk that an owner is willing to accept before tree failure.
accessibility:
the establishment of a location used to enter a site.
acidic soil:
having a pH les than 7.0, in contrast with alkaline which has a pH that is higher than 7.0.
actinomycetes:
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:
the number of distinct motions for the carabineers and snaps gate to be opened.
,action threshold:
the point at which a pest requires the implementation of a management tactic or control.
acute crotches:
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:
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
a boundary on the ground delineated by the branch spread of a single tree or group of trees.
adsorption:
adhesion on contact of molecules to the surface of solids or liquids with which they are in
contact.
advanced assessment:
an assessment performed to provide detailed information about specific tree parts, defects or
site conditions.
adventitious/epicormic growth:
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:
, 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:
the provision of air to the soil to alleviate soil compaction.
aerial lift device:
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:
a method of bringing an injured worker down from a tree.
aerial roots:
roots that grow from stems toward the soil with the capacity to become prop roots when they
anchor in the soil.
aerobic microorganisms:
these microbes require free, gaseous oxygen for growth.
aggregate:
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:
is a land use management system in which trees or shrubs are grown around or among crops
or pastureland.
Air Spade™:
