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Urban Forestry
Below is a glossary of terms commonly used in the tree care industry:
ANSI A300 - industry-developed, national consensus standards of practice for tree care, in the United States
ANSI Z133 - industry-developed, national consensus safety standards of practice for tree care, in the United States
Adventitious Roots - roots that form on trunks and branches when in contact with moist soil or organic material.
Best Management Practices - best-available, industry recognized courses of action, in consideration of the benefits and limitations, based on scientific research and current knowledge
Branch Bark Ridge - raised strip of bark at the top of a branch union where the growth and expansion of the trunk or parent stem and adjoining branch push the bark into a ridge
Branch Collar - the area of swelling at the union between a parent stem and a smaller branch
Broadleaf – Trees that have broad, flat leaves as opposed to needles
Buds – Embryonic leaves, shoot, and/or flower contained in protective tissue through the winter
Caliper – Diameter of the tree measured at the ground. Only used for nursery trees below 6 inches in diameter
Cambium – Thin layer of cells that produces new wood
Canopy – The layer made up of all tree crowns in a specified area
Certified Arborist – An arborist that is certified by the International Society of Arboriculture to possess technical skills and knowledge through experience and training to manage or provide expertise on the management of trees
Codominant - branches of similar diameter arising from a common union and lacking a collar.
Compartmentalization - the natural defense process in trees; implementation of chemical and physical boundaries to limit the spread of disease and decay organisms
Conifer – A tree with needles instead of leaves. Most are evergreen, however some are deciduous
Critical root zone – An area near the trunk of the tree where the large anchoring roots are located
Crown – the upper part of a tree, measured from the lowest branch, including all the branches and foliage
DBH (Diameter at Breast Height) – Diameter of the tree measured at 4.5 ft above the ground
Deciduous – Trees that lose their leaves each year. These are usually broadleaf trees, but several conifers are deciduous
Dominant Leader/Stem - the stem that grows much larger than all other stems and branches
Drip line – imaginary line defined by the branch spread of a single plant or group of plants
Drought-tolerant – Trees that are more adapted to withstand extended dry periods when they are mature. ALL TREES STILL NEED WATER, but especially young trees. Drought-tolerant does not mean you don’t have to water the tree.
Fine/Feeder Roots – Non-woody roots that occur in greatest abundance near the soil surface and are the principal point of entry for water and minerals.
Girdle – To constrict the vascular tissue inhibiting growth and the movement of water and nutrients.
Girdling root – A root that has grown to encircle the main stem of the tree and girdles the tree
Hanger – A large branch that is broken and hanging in the tree
High-voltage transmission lines (HVTL) – Utility wires that transmit power throughout the electrical grid. These require high clearance and are different than cable or other small electric lines that do not require large clearances. Trees near HVTL need to be pruned by utility companies and must have large clearances.
Included Bark - bark that becomes embedded in a union between branch and trunk or co-dominant stems. Causes a weakness in the union indicating likely failure of the junction
Lion-tailing - excessive removal of lower or interior branches on main scaffolds that results in a concentration of growth and foliage at branch ends. This is considered an unacceptable practice
Mature Trees - trees that have reached at least 75 percent of their typical final height and spread
Park strip – Area of landscaping between the sidewalk and street
Permanent Branches - branches that form the architectural framework of a tree
Pruning – An intentional process of cutting tree branches to promote tree health/safety. Pruning is not randomly cutting branches with no clearly defined end-goal
Public right-of-way – City-owned strip of land extending from the center of the street to a defined distance
Reduction Cut - a pruning cut that removes the larger of two branches back to a lateral that will assume dominance and able to sustain the branch; technique for keeping branches small.
Removal – Work done by professionals to safely take a tree out of the landscape. Urban Forestry removes trees due to safety issues or the health of the tree is beyond remediation
Root Flare/Collar - the transitional area between woody arid-tolerant tissue (trunk) and moisture-tolerant tissue (roots)
Stem - woody structure bearing foliage and buds that gives rise to other stems (branches)
Street tree – City-owned tree growing in a park strip or median along a street
Structural Roots - Large, woody, roots that anchor and support a trees trunk and crown
Subordination - the removal of the end of a branch or stem to slow its growth relative to its parent, or to a favored branch or stem
Temporary Branches - Branches retained on a tree for the first few years, with the intention to ultimately remove; these should be reduction pruned yearly so they stay small
Topping – the reduction of tree size by heading large, live branches and leaders without regard to long-term tree health or structural integrity.
Tree – a woody perennial plant with a single or multiple trunks, which typically develop a mature size of over several inches in diameter and 10 feet or more in height
Tree Protection Zone – A fenced-off area around existing trees during construction activity
Trunk – Main stem of the tree between the root collar and the first branches.
Union - the junction of stem and branch or between stems
Vascular Tissue – The structures in a tree that carry water and nutrients throughout the tree (xylem and phloem).