Arboriculture: the art, science, technology, and business of commercial, public, and utility tree care.
Arborist: A professional who possesses the technical competence through experience and related training to provide for, or supervise the management of tree and other woody plants in the residential, commercial, and public landscape.
Bracing: the installation of lag-thread screw or threaded-steel rods in limbs, leaders, or trunks to provide supplemental support.
Branch collar: The swollen area at the base of a branch.
Cabling: The installation of a steel wire rope, steel strand, or synthetic-fiber system within a tree between limbs or leaders to limit movement and provide supplemental support.
Caliper: In the landscape or nursery trade, this is the diameter of a tree, measured at a point 6 inches above the ground line if the resulting measurement is no more than 4 inches. If the resulting measurement is more than 4 inches, the measurement is made at a point 12 inches above the ground line. This in contrast to the method used to measure caliper in the timber industry, which is to make the measurement at a point 4.5 feet above the ground line, or the “diameter breast height” (DBH).
Callus: Undifferentiated tissue formed by the cambium around a wound
Cambium: the dividing layer of cells that forms sapwood (xylem) to the inside and inner bark (phloem) to the outside.
Cleaning: Selective pruning to remove one or more of the following parts: dead, diseased, and/or broken branches.
Closure: the process of woundwood covering a cut or other tree injury.
Critical Root Zone: The minimum volume of roots necessary for maintenance of tree health and stability.
Crown: The leaves and branches of a tree measured from the lowest branch on the trunk to the top of the tree.
DBH: [diameter at breast height]: Measurement of trunk diameter taken at four-and-one-half feet off the ground
Decay: The degradation of woody tissue caused by microorganisms.
Development Impacts: Site development and building construction related actions that damage trees directly, such as severing roots and branches, or indirectly, such as soil compaction.
Drip Line: A boundary on the soil surface delineated by the branch spread of a single plant or group of plants.
Espalier: The combination of pruning, supporting, and training branches to orient a plant in one plane.
Girdling Root: A root that may impede proper development of other roots, trunk flare, and/or trunk.
Growth Habit: The mode or rate of growth, general shape, mature size, and branching structure of a plant, including the changes which take place seasonally during its life cycle (e.g., deciduous, flowering, fruiting, etc.)
Guying: The installation of a steel cable or synthetic-fiber cable system between a tree and an external anchor to provide supplemental support.
Hazard Tree: A visibly damaged, dead, diseased, leaning or dying tree that, should it tail, could contact the conductors. These trees have the potential to fall into, bend into, or grow into conductors.
1) Cutting a currently growing, or a 1-year-old shoot, back to a bud.
2) Cutting an older branch or stem back to a stub in order to meet a defined structural objective.
3) Cutting an older branch or stem back to a lateral branch not large enough to assume apical dominance in order to meet a defined structural objective. Heading may or may not be acceptable pruning practice depending on the application.
Interfering Branches: Crossing, rubbing, or upright branches that have the potential to damage tree structure and/or health.
Lateral Branch: a shoot or stem growing from a parent branch or stem.
Leader: A dominant or co-dominant, upright stem.
Limb: A large, prominent branch.
Line-Clearance: Tree Trimming The pruning, trimming, repairing, maintaining, removing, or clearing of trees or the cutting of brush that is within 10 feet (305 cm) of electric supply lines and equipment.
Lion’s Tailing: the removal of an excessive number of inner, lateral branches from parent branches. Lion’s tailing is not an acceptable pruning practice.
Micronutrient: Nutrient required in relatively small amounts by plants, such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B).
Nutrient: Element or compound required for growth, reproduction or development of a plant.
Parent Branch or Stem: A tree trunk, limb, or prominent branch from which shoots or stems grow.
Petiole: A stalk of a leaf or frond.
Phloem: Inner bark conducting tissue that transport organic substances, primarily carbohydrates, from leaves and stems to other parts of the plant.
Planting: Installing a plant in the landscape.
Pollarding: The maintenance of a tree by making intermodal cuts to reduce the size of a young tree, followed by the annual removal of shoot growth at its point of origin.
Pruning: the selective removal of plant parts to meet specific goals and objectives.
Qualified Arborist: An individual who, by possession of a recognized degree, certification, or professional standing, or through related training and on-the-job experience, is familiar with the equipment and hazards involved in arboricultural operations and who has demonstrated ability in the performance of the special techniques involved.
Qualified Tree Worker, Person, or Personnel: A person(s) who, through related training and on-the-job experience, is familiar with the hazards of pruning, trimming, repairing, maintaining, or removing trees with the equipment used in such operations, and has demonstrated ability in the performance of the special techniques involved.
Raising: Selective pruning to provide vertical clearance.
Reduction: Selective pruning to decrease height and/or spread.
Restoration: Selective pruning to improve the structure, form and appearance of trees that have been severely headed, vandalized, or damaged.
Root Collar: the transition zone between the trunk and the root system.
Root Flare or Trunk Flare: The area at the base of the plants stem or trunk where the stem or trunk broadens to form roots; the area of transition between the root system and the stem or trunk.
Root Pruning: The cutting of roots to meet specific goals and objectives.
Secondary Nutrient: Nutrient required in moderate amounts by plants, such as calcium (Ca) and magnesium (Mg).
Slow-release Fertilizer: A fertilizer containing plant nutrients in a form that delays availability for plant uptake and use after application, or that extends availability to the plant.
Soil Amendment: any material added to soil to alter its composition and structure, such as sand, fertilizer, or organic matter.
Soil Anchor: A device driven, buried, or otherwise inserted into the ground to which a guy is attached.
Spread: A term used to indicate the horizontal width of a shrub or the crown of a tree. Techniques for proper measurement are determined by the particular growth habit of the plant, and may not always be to the maximum distance between any two branch tips.
Stub: An undesirable short length of a branch remaining after a break or incorrect pruning cut is made.
Suitability for Conservation: A rating system that combines tree health and structure with species tolerance to development impacts.
Thinning: Selective pruning to reduce density of live branches.
Topping: The reduction of a tree’s size using heading cuts that shorten limbs or branches back to a predetermined crown limit. Topping is not an acceptable pruning practice.
Tracing: The removal of loose, damaged tissue from in and around the wound.
Transplanting: The process of relocating an existing plant in the landscape.
Tree Inventory: A comprehensive list of individual trees providing descriptive information on all or a portion of the project areas.
Tree Protection Zone Barriers: Devices such as fencing, berms, or signage installed to limit access to tree protection zones.
Tree Protection Zone: A space above and below ground within which trees are to be retained and protected.
Tree Support System: A support system used to provide supplemental support to leaders, individual limbs, and/or the whole plant.
Tree Survey: A description of trees within all or a portion of the project area based on defined criteria, such as representative sampling or tree size.
1) The area at the base of the plant’s stem or trunk where the stem or trunk broadens to form roots.
2) The area of transition between the root system and the stem or trunk.
Trunk: That portion of a stem or stems of a tree before branching occurs.
Vista Pruning: Selective pruning to allow a specific view.
Watersprouts: New stems originating from epicormic buds.
Whorl: The arrangement of three or more buds, leaves, flowers, or twigs at the same node.
Wound: An opening that is created when the bark of a live branch or stem is penetrated, cut, or removed.
Woundwood: Partially differentiated tissue responsible for closing wounds. Woundwood develops from callus associated with wounds.
Xylem: Wood tissue. Active xylem is sapwood; inactive xylem is heartwood.
Young Tree: A tree young in age or a newly transplanted tree.