Arboriculture Glossary of Terms
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- D-ringsD-shaped metal rings on a climber's saddle for attaching ropes and snaps.
- DAFBdiameter above flare or buttress
- dBdecibel
- dbhacronym for tree diameter at breast height. Measured at 1.4 m ( 4.5 feet) above ground in the United States. Australia (arboriculture). New Zealand. and when using the Guide for Plant Appraisal (9th ed.); at 1.3 m ( 4.3 feet) above ground in Australia (forestry). Canada. the European Union. and UK (forestry); and at 1.5 m (5 feet) above ground in UK (arboriculture).
- DdRTacronym for doubled rope technique. Dynamic or static climbing system in which a rope is doubled over a branch and the climber uses both parts of the line (contrast with DRT and SRT).
- dead-end bracea brace formed by threading a lag-threaded screw rod directly into a limb. leader. or trunk but not through the side opposite the installation.
- dead-end gripsa manufactured wire wrap designed to form a termination in the end of a 1 x 7 left-hand lay cable.
- dead-end hardwareanchors or braces that are threaded directly into the tree but not through the side opposite the installation. Dead-end hardware includes but is not limited to lag hooks. lag eyes. and lag-threaded screw rods.
- dead-eye slingrope sling with a single eye spliced in one end. Also called eye sling. fixed-eye sling. or spliced-eye sling.
- deadwoodingremoving dead and dying branches from a tree. Outdated term for crown cleaning. which is more comprehensive.
- deciduoustree or other plant that sheds all of its foliage annually (contrast with evergreen).
- declineI) gradually diminishing health or condition of a tree. 2) a pattern of decline conditions in a particular species not necessarily associated with a single cause. e.g.. ash decline.
- decline spiralinteraction of causal agents that accelerates decline (see mortality spiral).
- decurrentrounded or spreading growth habit of the tree crown (contrast with excurrent).
- DEDDutch elm disease
- deficiencypertaining to plant nutrition. lack or insufficient quantity of a required element.
- defoliationloss of leaves from a tree or other plant by biological. chemical or mechanical means (as opposed to natural shedding).
- degree daya measure of heat accumulation over time that allows comparison of the daily average temperature and a given temperature base. Used to plan. monitor. or schedule plant or pest management. Also growing degree day.
- dehiscentsplitting apart. Describes the release of seed capsules at maturity.
- dehydrationLoss of water from plant tissue
- deicing saltsA combination of salts that are spread to keep areas such sidewalks and roadbeds free of ice
- Delonix regiaFlame Tree - Flame of the Forest -
- denitrificationprocess of reducing nitrates to nitrogen gases.
- dentatehaving serrations (teeth) perpendicular to the leaf margin (compare to serrate).
- desalinated waterseawater that has undergone treatment to remove much of the salts.
- descenderdevice used to control friction when descending a climbing line (contrast with ascender).
- desiccationsevere drying out. Dehydration.
- design criteria1) aspects of the landscape or site and the required functions to be served by the plant that must be considered in plant selection. 2) factors considered in the design of equipment.
- design factorfactor by which the rated or minimum breaking strength of a rope or piece of equipment is divided to determine its working-load limit. For example a rated strength of 10.000 lbs. and a design factor of 2.0 would result in a safe working load of 5.000 lbs. (compare with safety factor).
- determinate growthdevelopment to a point characterized by a fixed number of leaves or other lateral organs (contrast with indeterminate growth).
- diagnosisl) process of identifying a causal agent by analyzing signs. symptoms. site conditions. patterns. climate. cultural history. and other factors. 2) the conclusion from the process.
- Dianella ensifolia Dianella ensifolia
- dibdiameter inside bark
- dicotsee dicotyledon.
- dicotyledonplant with two cotyledons in its embryo. Dicotyledons constitute the larger of the two great divisions of flowering plants. and typically have broad. stalked leaves with netlike veins (contrast with monocotyledon).
- diebackcondition in which the branches in the tree or other plant crown die from the tips toward the main stem.
- dielectricinsulating (nonconducting) material.
- differentiationprocess in the development of cells in which they become specialized for various functions.
- diffuse porouspattern of wood development in which the vessels and vessel sizes are distributed evenly throughout the growth ring (contrast with ring porous).
- Dimocarpus longanLungan - Longan
- DINacronym for Deutsches Institute fiir Normung. a national consensus standards-setting body in Germany.
- DIN 18916in Germany. standard that addresses plants and planting in the landscape industry.
- DIN 18919in Germany. standard that addresses development and maintenance of green areas.
- DIN 18920in Germany. standard that addresses the protection of trees on construction sites.
- dioecioushaving male and female flowers borne on separate individuals of the same species (contrast with monoecious).
- direct cable systemin tree support systems. simple tree cabling system joining two branches or leaders with a single cable (contrast with box cable system and triangular cable system).
- direct contactany part of the body touching an energized conductor.
- directional pruningproviding clearance by pruning branches that could significantly affect the integrity of utility facilities or other structures. and leaving in place branches that could have little or no effect.
- diseasecondition that impairs the performance of one or more vital functions. Usually associated with biotic or parasitic agents (contrast with abiotic disorder).
- disease complexcombination of factors contributing to the stress or decline of a tree.
- disorderabnormal condition that impairs the performance of one or more vital functions. Often associated with noninfectious agents or abiotic factors (contrast with disease).
- Disteltype of friction hitch used in climbing and rigging.
- divisionphylum. Taxonomic group below the kingdom level but above the class level.
- division phylumtaxonomic group below the kingdom level but above the class level.
- dominant leaderthe one stem that grows much larger than all other stems and branches; at least one third larger than lateral branches nearby.
- dormancyperiod of naturally reduced physiological activity in the organs of a plant with the potential for reactivation of growth.
- dormantin a period of dormancy.
- dormant budbud originally developed in a leaf axil and connected to the pith by a bud trace that has not been stimulated to mature and grow. Some buds remain dormant throughout the life of a woody plant.
- dormant oilssee horticultural oils.
- double braidrope construction consisting of a braided core within a braided rope. both of which carry part of the load (contrast with kernmantle rope).
- double crotchtechnique consisting of tying one climbing line or two climbing lines into two places in a tree.
- double figure-S knotfigure-8 knot tied with two strands of rope.
- double fisherman's bendin arboriculture. the name used for a knot that is commonly used to join two ropes or two ends of the same rope. as when forming a Prusik loop. Grapevine knot.
- double half hitchtwo half hitches tied in a series.
- double hitchtechnique consisting of securing a tree section with two load lines in rigging.
- double-lockingpertaining to a carabiner. requiring two distinct motions to prepare the gate to open.
- double serratetoothed margin of a leaf. with smaller teeth within the teeth.
- downy mildewany of various oomycetes (not true fungi) producing white. fungal-like growth that develops during wet periods. usually on the underside of a leaf (contrast with powdery mildew).
- Dracaena reflexa Song of IndiaDracaena reflexa Song of India
- Dracontomelon duperreanumYanmin
- drift linein tree rigging. variation on the load transfer technique in which the load is transferred to a second line and moved to another point. often to a second tree.
- drill-hole fertilizationapplying fertilizer by drilling holes in the soil within the root zone (contrast with broadcast fertilization and liquid fertilization).
- drip irrigationmethod of minimizing evaporation and runoff by applying small amounts of water through small emitters.
- drip lineimaginary line defined by the branch spread of a single plant or group of plants.
- dropcrotch pruning (obsolete) term for a method of reducing the height of a tree. The general rule for cuts is that leaders should be cut back to a lateral capable of assuming apical dominance. if possible. usually at least one third the diameter of the leader. See reduction.
- drop-crotch pruning(obsolete) term for a method of reducing the height of a tree. The general rule for cuts is that leaders should be cut back to a lateral capable of assuming apical dominance. impossible. usually at least one-third the diameter of the leader (see reduction).
- drop cutbranch-removal technique consisting of an undercut and then a top cut. usually made farther out on the branch. or with a chain saw. directly over the undercut.
- drop linerope used to secure the weight of a limb in rigging; load line.
- drop starttechnique used to start a chain saw by pushing the saw away from the body and simultaneously pulling the start cord.
- drop zonepredetermined area where cut branches or wood sections will be dropped or lowered from a tree (see landing zone).
- droughtperiod of unusually low precipitation.
- DRTacronym for double rope technique. Climbing system in which two separate ropes and two separate anchor points are utilized (contrast with DdRT and SRT).
- drum lacemethod of tying the root ball of a balled-and-burlapped tree for moving.
- drupestony seed inside a fleshy covering (for example. cherry and peach).
- dry season dormancydrought adaptation of acclimated plants that become dormant during the dry season.
- dshdiameter at standard height
- DWdeadwood
- dynamic cable systemany of several cabling systems that utilize elastic materials (usually rope of various constructions) for tree support systems.
- dynamic loadforces created by a moving load. Load that changes with time and motion (contrast with static load).
- dynamicsstudy of how objects move under the action of forces (contrast with statics).
- dynamometerinstrument for measuring mechanical force or power.