Arborist glossary

The terms cover pruning, removal, crane work, stumps and roots, fire and land clearing, Lake Tahoe permits, and firewood. If a word on your estimate is not here, ask the arborist. Every estimate should be easy to understand.

Terms, A to Z

811

The national call-before-you-dig number. Underground utilities are marked before any digging, which includes grinding a stump below grade.

ANSI A300

The American National Standards for tree care work, including pruning. It is the standard the industry follows, and it does not accept topping as pruning.

ANSI Z133

The American National Standard for safety in tree work, covering climbing, rigging, aerial lifts, chippers and work near power lines.

Arborist

A person trained in the care of individual trees. An ISA Certified Arborist has passed the International Society of Arboriculture's exam and keeps the credential current with continuing education.

Boom truck

A truck with an extending boom and a bucket that lifts an arborist into the crown. Also called a bucket truck or aerial lift. Ours is a 75-foot Altec GMC.

Branch collar

The slightly swollen ring where a branch joins the trunk. A correct pruning cut is made just outside it so the wound can close.

Brush mowing

Cutting brush and tall weeds with a heavy mower, often for fire fuel reduction on open lots.

Cabling and bracing

Installing cables or rods in a tree to support weak unions or heavy limbs.

Canopy

The combined crowns of the trees over a yard, street or lot. Also used for the leafy part of a single tree.

Cavity

A hollow in a trunk or limb where decayed wood has gone.

Chipper

The machine that turns limbs and brush into wood chips, usually towed behind the chip truck.

Climber

The crew member who works in the tree on ropes and a harness, making the cuts and attaching the crane or the rigging.

Codominant stems

Two or more trunks of about the same size growing from one fork. The union between them is often weak.

Conifer

A cone-bearing tree, usually evergreen with needles or scales, such as a pine, fir, spruce, cedar or juniper.

Conk

The shelf-like fruiting body of a wood decay fungus on a trunk or at the base of a tree. It is a sign of decay inside.

Cord

The standard measure of firewood: 128 cubic feet of stacked wood, such as a stack 4 feet high, 4 feet deep and 8 feet long. See how big a cord is.

Crane-assisted removal

Removing a tree in sections that a crane lifts up and away to a drop zone, instead of lowering each piece on ropes. See how we do it.

Crown

The branches and foliage of a tree, above the trunk.

Crown cleaning

Pruning out dead, dying, broken and rubbing branches without changing the size or shape of the tree.

Crown raising

Removing the lowest branches for clearance over a roof, driveway, walk or street. Also called limbing up.

Crown reduction

Shortening a tree's height or spread by cutting back to side branches large enough to take over. It is not topping.

Crown thinning

Removing selected branches through the crown to reduce weight and wind load while keeping the tree's shape.

DBH (diameter at breast height)

The diameter of a trunk measured 4.5 feet above the ground. Wrap a tape around the trunk and divide by 3.14. Tahoe permit rules are written in DBH.

Dead wooding

Removing dead, dying and broken branches from a tree.

Decay

Wood breaking down from fungi inside a trunk, limb or root. It can be hidden behind sound-looking bark, which is why an arborist looks for cavities, conks and cracks.

Deciduous

A tree that drops its leaves each fall, such as a cottonwood, maple, elm or ash.

Defensible space

The area around a building where plants and other fuels are managed to slow a wildfire. The Living With Fire guide divides it into Zone 0 (0 to 5 feet), Zone 1 (5 to 30 feet) and Zone 2 (30 to 100 feet).

Dieback

Branches dying from the tips inward, often from drought stress, root damage or disease.

Dormant season

The part of the year when a tree is not actively growing. Most deciduous trees are pruned in late winter, while dormant.

Drip line

The line on the ground under the outer edge of a tree's branches.

Drop zone

The cleared area where the crane sets down each section of a tree to be cut up and loaded.

Fire mitigation

Assessing a property's specific fire risks and removing fire fuel from around it to create a defensible zone.

Flush cut

A cut made tight against the trunk that removes the branch collar. It leaves a larger wound that closes poorly.

Girdling root

A root that circles the base of the trunk and squeezes it as both grow.

Hardiness zone

A USDA map zone based on the average coldest winter temperature. Our service area runs from zone 6b to zone 7b on the 2023 map.

Heading cut

A cut that shortens a branch to a bud or a small twig rather than to a side branch. Repeated heading cuts on large limbs are topping.

Included bark

Bark trapped inside a tight fork between two stems. It keeps the wood from joining and is a common place for a tree to split.

ISA Certified Arborist

A credential issued by the International Society of Arboriculture to a person, not a company. Each holder has a certificate number, such as WE-11728A, that can be checked with the ISA. See what the credential means.

Ladder fuels

Low branches, shrubs and small trees that let a ground fire climb into the crowns of larger trees.

Lateral

A side branch. A proper reduction cut shortens a limb back to a lateral big enough to take over.

Leader

The main upright stem at the top of a tree.

Lean

The angle of a trunk away from vertical. A long-standing lean with a curved top is different from a new lean with lifting soil, which needs to be looked at right away.

Lot clearing

Removing trees, brush and debris from a parcel, for building, access or fire safety.

Mastication

Grinding standing brush and small trees into chips with a machine-mounted cutting head, leaving the chips on the ground.

Outriggers

The legs a crane or boom truck extends to steady itself before lifting.

Rigging

The ropes, slings and hardware used to lower cut pieces of a tree under control.

Right-of-way

The strip of public land along a street, which often includes the area between the sidewalk and the curb. In Reno, work on trees in the City right-of-way needs a Tree Work Permit and a Certified Arborist.

Root barrier

A panel set in the soil to steer roots away from pavement, pipes or foundations.

Root flare

The base of the trunk where it widens into the main roots. It should be visible at the soil line.

Seasoned firewood

Firewood that has been split and dried long enough to burn cleanly. Freshly cut wood is called green.

Shaping

Light pruning to keep a tree or shrub in a tidy, balanced form.

Skid steer

A compact wheeled loader that turns by skidding its wheels. Used for moving material, grading and snow.

Slash

The limbs, tops and brush left over from cutting. It is chipped, masticated or hauled so it does not become fuel.

Snag

A standing dead tree.

Structural pruning

Pruning a young tree so it grows one strong central trunk and well-spaced branches. It is the usual pruning for young trees.

Stub

A length of branch left sticking out past the collar after a poor cut. Stubs die back and invite decay.

Stump grinding

Grinding a stump below the surface with a machine so the area can be replanted or covered.

Stump removal

Taking out a stump. Most often done by grinding. Digging out the whole stump and root ball is a bigger job. See grinding versus full removal.

Topping

Cutting the top of a tree back to stubs. It weakens the tree and is not accepted pruning practice under the ANSI A300 standard. See why topping is not pruning.

Track loader

A compact loader on rubber tracks, such as our Bobcat T870. It carries logs, loads trucks and runs attachments like the masticating head.

TRPA

The Tahoe Regional Planning Agency. In the Tahoe Basin it requires a permit to remove a live tree over 14 inches DBH, or over 6 inches DBH between the house and the lake on lakeshore lots.

Utility and structure clearance

Pruning branches back from buildings, roofs and service lines.

Water sprouts and suckers

Fast, weakly attached shoots. Water sprouts grow from limbs, often after hard pruning or topping. Suckers grow from the roots or the base of the trunk.

Widow-maker

A broken limb hanging in a tree that can fall without warning. Also called a hanger.

Wildland-urban interface (WUI)

Neighborhoods and homes that are in or next to wildland vegetation.

Windthrow

A tree blown over at the roots, with the root plate lifted out of the ground.

Wood chips

What the chipper makes from limbs and brush. Used as mulch away from the house, never in Zone 0.

Zone 0

The ember-resistant zone, 0 to 5 feet from the house. The Living With Fire guide says to remove woodpiles, combustible mulch, and junipers and other high-fire-hazard plants from it.

Zone 1

The lean, clean and green zone, 5 to 30 feet from the house in the Living With Fire guide.

Zone 2

The reduced fuel zone, 30 to 100 feet from the house in the Living With Fire guide, where dead vegetation and ladder fuels are removed.