Douglas L. Airhart & Guy Zimmerman III

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Right Tree / Right Place

Selecting Trees

Transplanting Trees

Mulching & Staking

Summary Diagram 

Pruning Trees

Topping Hurts!

Protecting Trees

Tree Root Myths

Pine Bark Beetles

Live Christmas Trees


List of Figures

List of Video Vignettes

Related Links



Glossary of Professional Terms:

Absorbing roots – small and fibrous, they take up water and nutrients; usually found at shallow depth in the root zone.

Absorption – taking up.

Access route – roadway for entering and leaving a construction zone.

Aeration – drilling holes or pumping air into root zones to overcome compaction or improve water movement.

ANSI A300 – American National Standards Institute; standards of treatment for tree care practices.

ANSI Z133.1 – American National Standards Institute; standards of safety for tree care practices.

Antitranspirant – chemical applied to plants to reduce water loss through leaves and stems.

Anvil pruner – tool with straight blade that presses onto a flat surface; not recommended for tree pruning.

Arboriculture – science of growth and development of trees, and tree care practices.

Backfill – soil and any amendments used to cover roots during transplanting.

Balled and burlapped – trees grown in field soil and harvested manually or mechanically; wrapped in burlap with twine, and may have wire cage for larger trees.

Bare root – trees grown in field soil but shaken or rinsed to remove soil when harvested; handled during dormancy. Smaller specimens usually, but survival of larger root masses is possible with hydrogel products.

Bark – outer layer of stems and trunks; protective tissue.

Barrier – fenced or otherwise designated boundary of root protection zone during construction.

Branch – stem originating from another, larger stem.

Branch bark ridge – protruding bark at the top of the junction (crotch) of two branches; continues downward from crotch.

Branch collar – junction (overlap) of tissues of two branches or branch and trunk.

Bud – small dormant apical or lateral meristem; may be foliar or floral tissue; undeveloped  flower or stem.

Buttress root – large woody root extending trunk into the soil; part of root flare.

Bypass pruner – tool with curved lower and cutting blades that slide past each other to operate.

Cambium – layer of lateral meristematic cells; produces phloem and xylem tissue.

Canopy – branch and leaf portion of tree (also called ‘crown’).

Carbohydrate – energy-storage compound produced by photosynthesis.

Cavity – open wound or hollow in trunk of tree; result of decay.

Central leader – main growing terminal stem of a tree.

Certified arborist – professional tree service provider; certification regulated and maintained with International Society of Arboriculture. Certified Arborist: an individual who has passed the certification examination sponsored by the International Society of Arboriculture and who maintains a current certification.

Codominant stems – two equally competing terminal branches.

Compaction – squeezing of soil that results in loss of pore spaces.

Containerized – trees grown in pots in a nursery since propagation, usually in a soil less mix; may have been stepped-up numerous times before sales.

Crotch – top of the union of two branches or of branch and trunk.

Crown – aboveground portion of tree.

Crown cleaning – removal of watersprouts, suckers, dead, dying, diseased, deformed and damaged branches.

Crown reduction – alternative to topping; reducing canopy by appropriate pruning techniques.

Crown restoration – technique to restore growth habit of topped or damaged tree.

Decay – deterioration of woody tissue by diseases.

Deciduous – trees that drop their leaves in winter.

Desiccation – extreme drying out.

Dieback – condition of death of many terminal branches.

Dormant – at rest, or in a state of reduced activity.

Drip line – boundary of the canopy.

Drop cut – second cut in 3-cut process of removing a branch.

Drop zone – area where cut branches may fall during pruning.

Evergreen – trees that keep their leaves or needles year-round.

Extension pruner – hook and blade bypass pruning tool on telescoping handle, operated by rope.

Fail – a tree or branch breaks or falls.

Flush cut – improper pruning technique; removes branch collar and damages trunk.

Girdling root – root growing around part of the trunk, restricting its expansion.

Guying – stabilizing a tree with ropes or wires attached to ground staubs.

Hand pruners – tool for one-handed cutting of smaller stems.

Hardened off – gradually introduced to a new environment.

Hardiness – ability to withstand cold or warm temperatures.

Hardiness zone – sections of the country designated by expected range of low temperature.

Hazard potential – likelihood of failure and damage posed by a tree.

Heading back – pruning shoots back one-half to one-third to buds or twigs with potential for growth.

Heartwood – inner wood (nonfunctioning xylem) that gives strength to the trunk.

Horizon – layer of soil in the profile.

Included bark – bark tissue lodged in the crotch of two branches or branch and trunk indicating weak attachment.

Invasive species- an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health, as defined by the Department of Agriculture.

Lateral – side branch or smaller twig of a limb.

Lateral bud – vegetative bud on side of a branch.

Lateral root – branching root beyond buttress root zone.

Leader – primary terminal stem of a tree or scaffold branch.

Liability – legal responsibility; generally associated with probable cost to repair damage.

Lopper – tool for two-handed cutting of larger stems.

Lowest permanent branch – lowest limb that will remain in tree canopy.

Main branches – those that make up the canopy of the tree (scaffold branches).

Mature height – tallest expected growth of a tree.

Mature tree – has reached approximately 75% of its full canopy growth.

Mechanical trimming- cutting of plant parts by any power-drive method other than chainsaw or boom-axe.

Meristem – tissue capable of dividing to form new cells.

Multiple leaders – codominant stems competing for central growth of tree.

Mycorrhizae – fungus root; symbiotic combination of fungus and root tissue.

Native - a species that historically occurred in a physiographic region of Virginia.

Natural target pruning – technique of removing branch that protects the branch collar; 3-cut  process.

Node – point of attachment of leaves and axillary buds.

Permanent branch – branch that will remain on tree; initial scaffold framework.

pH – measurement of acidity level of soil.

Phloem – food-conducting tissue of tree just outside of cambium.

Photosynthesis – food-making process of green plants.

Planting specifications – detailed diagrams and statements specifying techniques for installing trees.

Pole pruner – long-handled pruner to reach into canopy without a ladder.

Pole saw – long handled tool with tree saw on the end.

Pollarding – specific pruning technique for height restriction of trees.

Pruning – cutting away undesirable parts of a tree.

Radial trenching – technique for improving soil aeration in root zones; trench radiates from trunk.

Raising – removing lower branches to provide clearance.

Reduction – pruning to reduce height and/or spread of canopy.

Respiration – cellular process releasing energy from stored foods.

Restoration – pruning to recover shape and strength of damaged canopies.

Riparian Buffer- a band of trees, shrubs, or grasses that border a body of water.

Root ball – remaining root and soil after tree is field-harvested.

Root flare – base of trunk that swells out to become buttress roots entering the soil; root collar.

Root pruning – cut or remove any circling or girdling roots; cutting roots to increase density of root mass.

Scabbard – sheath for tree saw.

Scaffold limb – permanent, main branch of the canopy. Ample vertical and radial spacing improves tree structure.

Sinker roots – deep-growing roots providing tree stability.

Site considerations – factors to take into account when determining what trees to select for the location.

Soil amendment – material mixed with soil to adjust physical or chemical status.

Soil analysis – determination of pH and mineral status (P and K usually) of soil.

Soil compaction – pressing of soil that removes pores, eliminating water- and air-holding capacity.

Staking – using stakes to support newly planted trees.

Standards – specifications for tree installation, maintenance and/or pruning.

Stress – any of a group of factors that has a negative effect on tree health.

Structural defect – any flaw in a trunk, branch or root that weakens the tree, possibly leading to failure.

Structural pruning – pruning to develop a sound scaffold branch system in a tree.

Subordinate – prune a branch to retard its growth rate compared to competing branches.

Sucker – shoot originating from a root or lower trunk.

Sunscald – bark damage by excess sunlight and heat.

Taper – decrease in diameter of trunk and branches from the base toward the tip.

Temporary branches – shoots that remain during training of young trees, to be removed as tree matures.

Terminal bud – bud at the apex of a stem.

Tree-  woody vegetation two inches or greater in diameter to be measured at ground level.

Tree protection zone – area of tree roots to be designated by fencing to prohibit access during construction activities. Minimum 8-foot radius, or usually 1-foot radius per inch diameter at breast height.

Thinning – selective pruning of entire stems to increase air or light penetration to canopy or to decrease branch weight.

Topping – non-professional pruning technique; non-selective canopy reduction, often destructive to tree.

Transpiration – loss of water vapor from pores in leaves; cooling and nutrient transport process.

Transplant – install new tree into the landscape.

Transplant shock – environmental stress (moisture, heat) after installation due causing wilting or leaf drop.

Tree well – wall and root aeration system around tree and root zone when soil grade is raised.

Tree wrap – temporary material to protect trunk of recently transplanted trees.

Trunk – base stem of tree that supports canopy.

Tunneling – boring a hole under root zones; alternative to trenching to protect roots.

Turgid – adequate water pressure in tissues.

Undercut – first of 3-cut process in natural target pruning. Prevents bark tearing.

Vertical mulching – drilling vertical holes in root zone and filling with porous material to improve aeration and water penetration.

Water sprout – fast-growing, usually vertical shoot from a lateral branch.

Weak crotch – narrow angle connecting two branches or branch and trunk; often with included bark.

Wilt – loss of turgidity, drooping of leaves.

Wind throw – toppling failure due to high winds.

Wire basket – external supporting cage for large B&B root masses.

Wound dressing – not recommended; compound for covering cut branch ends.

Xylem – water-conducting tissue produced by cambium; becomes wood and provides structural support.

Text condensed and abridged from: Lilly, S. 2001. Arborists’ certification study guide. International Society of Arboriculture; and An Illustrated Guide to Pruning, 2cd edition, by Gilman. Copyright 2002. Reprinted with permission of Delmar Learning, a division of Thomson Learning. Fax 800-730-2215.


Purpose    Right Tree / Right Place    Selecting Trees    Transplanting Trees    Mulching & Staking    Summary Diagram     Pruning Trees    Topping Hurts!      Protecting Trees     Tree Root Myths     Pine Bark Beetles     Live Christmas Trees     Glossary     List of Figures    List of Video Vignettes    Related Links     Bibliography is maintained by: Douglas Airhart, Ph.D. Certified Arborist & Jeff Plant, Ph.D, Last Updated on: 07/11/03