Arboriculture Glossary of Terms
r
- radial aerationsee radial trenching.
- radial transportlateral movement of substances. perpendicular to the longitudinal axis of the tree or stem.
- radial trenchingtechnique for relieving soil compaction and improving rooting conditions around a tree by digging or excavating trenches in a spoke-like pattern radially from the trunk. then backfilling. Often performed with air excavation equipment to minimize root damage (see trenching).
- raisingselective pruning to provide vertical clearance (see crown raising).
- ram's hornsinward curling formation of wound wood resembling the horns of a ram.
- Raphis excelsa Raphis excelsa
- Rare use Areas of rare access such as inaccessible areas, remote countryside slopes, dense woodlands, maintenance access not open for public, etc. Tree Risk Management Zone - Low (Category III) Priority for Tree Risk Management - Low priority Tree Risk Assessment Frequency - When necessary (e.g. act on complaint)
- raspingScraping. as in the rasping mouthparts of an insect
- ratcheting bollardBallard-type lowering device equipped with a mechanism for lifting loads.
- Ravenala madagascariensis Ravenala madagascariensis
- rayparenchyma tissues that extend radially across the xylem and phloem of a tree and function in transport. storage. structural strength. and defense.
- RCAASCA Registered Consulting Arborist
- RCEroot collar examination
- RCMreliability-centered management. replacement cost method
- RCXroot collar excavation
- reaction forceforce of equal magnitude exerted in the opposite direction of a force acting on a body.
- reactive forceforce generated in response and opposite to another force. Important concept for safely operating a chain saw.
- recycled waterwastewater that has been recovered and/or treated for potable or non-portable use.
- redirectI) v. changing the path of a climbing or rigging line to modify the forces on. or the direction of. the line. 2) n. a system installed to change the path of a climbing or rigging line.
- reductionpruning to decrease height and/or spread of a branch or crown.
- reduction cutpruning cut that reduces the length of a branch or stem back to a lateral branch large enough to assume apical dominance. Pruning method that reduces the height and/or spread of a plant. using reduction cuts and branch removal cuts.
- reduction pruningpruning method that reduces the length of a branch or stem back to a lateral branch.
- Reevesia thyrsoideaReevesia - Buch-like Reevesia
- regenerationtissue restoration or new growth produced by an organism. In forestry. establishment of new trees. either naturally or planted.
- reiterationan asexual reproductive strategy of trees such as aspen (Populus spp.) and willow (Salix spp.). which produce new trees or groups of trees by root suckering (see Slicker).
- reliability-centered management (RCM)in an electric utility system. scheduling of preventive maintenance (including utility arboriculture and IVM) to maximize electric service reliability and cost efficiency.
- removal cutcut that removes a branch just outside the collar at its point of origin. Collar cut.
- replacement cost method (RCM)method to appraise the monetary value of trees considered replaceable with nursery or field-grown stock. Based on the cost of replacement with the same or a comparable species of the same size and in the same place. subject to depreciation for various factors (contrast with trunk formula method).
- rescue kitclimbing gear and emergency equipment that should be sent out on every job site and made available to a worker conducting an aerial rescue or applying first aid.
- rescue pulleylight-duty pulley used in light rigging operations.
- resinSolid or semisolid natural organic flammable substance formed by plant secretions that are typically not water-soluble
- resistance1) in plants. the tendency to withstand certain pests. disease. or fungal problems; pest resistance. 2) in insects. the ability to withstand certain insecticides; survival of just a few genetically resistant insects that reproduce can lead to populations that are resistant.
- resistance-recording drillsee micro drill resistance testing.
- resistant varietiesplant varieties that are tolerant of. or not susceptible to. certain disease or pest problems or abiotic disorders.
- Resistographbrand name of a device consisting of a specialized micro-drill bit that drills into trees and graphs density differences that are used to detect decay. Invented and trademarked by Frank Rinn of Heidelberg. Germany.
- resonance testingnondestructive means of determining the soundness or structural integrity of an object or material by determining the rate at which magnetic. sound. or other waves travel through it.
- resource allocation1) in plant physiology. distribution and use of photosynthates for various plant functions and processes. 2) in management. distribution of materials or other assets to accomplish objectives.
- resource assessmentin urban forestry. an evaluation of trees based on inventory. canopy assessment. and/or sample surveys; may also consider factors affecting the urban forest such as soils. hydrology. water quality. temperature extremes. and wind.
- resource conservationactions and plans that protect and sustain natural plant and animal communities. soil. water. and ecosystems.
- respirationin plants. process by which carbohydrates are converted into energy by using oxygen.
- response growthnew wood produced in response r to loads to compensate for higher strain in outermost fibers; includes reaction wood (compression and tension) and woundwood.
- restoration1) pruning to improve the structure. form. and appearance of trees that have been vandalized. damaged. or improperly trimmed. 2) management and planting to restore altered or damaged ecosystems or landscapes. 3) replacement or reproduction of damaged or destroyed plants.
- retreat pathpredetermined escape route away from a tree that is to be felled. Should be a 45-degree angle back and away from the direction of the falling tree and clear of obstruction (see escape route).
- retrenchment1) natural process during which a mature tree reduces its crown and increases its girth to consolidate resources and increase longevity. 2) the deliberate process of reducing tree height to mimic natural processes.
- RFPrequest for proposal
- RFSRoyal Forestry Society
- rhizodermisprimary surface layer of the root. similar to epidermis but of different origin and function.
- rhizospheresoil area immediately adjacent to. and affected by. plant roots. Typically has a high level of microbial activity.
- Rhodoleia championiiRhodoleia -
- Rhoeo discolor Rhoeo discolor
- RHSRoyal Horticultural Society
- Rhus succedaneaWax Tree -
- RIDDORReporting of Injuries. Diseases. and Dangerous Occurrences Regulations
- rigging1) in tree pruning or removal. method of using ropes and hardware to control or direct the descent of cut material or to handle heavy loads. 2) with cranes. loaders. or other equipment. method of using ropes and hardware to lift heavy loads.
- rigging linerope. usually the load line. used in rigging operations.
- rigging pointthe place in the tree (natural or false crotch) that the load line passes through to control limb removal in rigging operations.
- right-of-way (ROW) (pl. rights-of-way)defined area of land. usually a linear strip. reserved for the passage of traffic (e.g.. paths and roadways) or the construction. maintenance. and operation of various aboveground or underground utilities. Rights-of-way may be granted by easement rights and may be across a single property or many properties (highways. railroads. or utility corridors are common examples).
- ring porousa pattern of wood development in which the large-diameter vessels are concentrated in the earlywood (contrast with diffuse porous).
- ring shake(s)see shake(s).
- riskthe combination of the likelihood of an event and the severity of the potential consequences. In the context of trees. risk is the likelihood of a conflict or tree failure occurring and affecting a target. and the severity of the associated consequences-personal injury. property damage. or disruption of activities.
- risk abatementapplying treatments that mitigate hazards and reduce risk.
- risk assessmentthe process of risk identification. analysis. and evaluation.
- risk avoidancerisk control strategy in which an activity is avoided to eliminate the possibility of loss (injury or damage).
- risk controlcomponent of a risk management program in which proactive measures or strategies are used to reduce risk.
- risk managementthe application of policies. procedures. and practices used to identify evaluate mitigate. monitor. and communicate tree risk.
- risk management plandocument that defines a tree risk management policy. describes tree inspection and documentation procedures. and provides an action plan to minimize risk.
- risk rating systemmethodology by which factors affecting the degree of risk are evaluated and assigned a rating.
- risk reductionprocess of taking action to lower risk of injury or damage.
- risk transferrisk control strategy that moves part. if not all. of the responsibility for risk assessment and/or abatement to another party.
- RLARegistered Landscape Architect
- rootplant organ. usually underground. that serves as anchorage. and also absorbs and conducts water and minerals.
- root ballsoil that contains all (i.e.. container grown) or a portion (i.e.. B&B) of the roots that are moved with a plant when it is planted or transplanted.
- root barriermembranes or sheets installed vertically in the soil to limit or direct the growth of tree roots.
- root boundcondition in which plant roots are overcrowded in a container or site and root growth is restricted.
- root capgroup of cells protecting the apical meristem at the root tip.
- root collarflared area at the tree trunk base where the roots and trunk come together (see root crown. root flare. and trunk flare) .
- root crownarea where the main roots join the plant stem. usually at or near ground level. Root collar.
- root crown excavation(root collar excavation) process of removing soil to expose and assess the root collar (root crown) of a tree.
- root flaresee trunk flare.
- root graftnatural union of two roots. either from the same plant or two different plants. Can result in disease transmission.
- root hairsmodified epidermal cells of a root that absorb the majority of water and minerals.
- root initiation zoneregion at the base of a palm stem where lateral roots emerge.
- root matdense network of roots. In palms. near the base of the stem.
- root platethe combination of large structural and smaller roots and soil near the base tree's trunk largely responsible for holding the tree erect.
- root protection area(RPA) in British Standards. area of tree root zone to be protected from construction damage. the size of which is based on the size of the tree or trees to be protected.
- root protection area (RPA)in British Standards. area of tree root zone to be protected from construction damage. the size of which is based on the size of the tree or trees to be protected.
- root protection zonearea of soil around a tree trunk where roots are located to be protected from construction damage. usually soil compaction damage. Rigid fencing is most effective for restricting access to this area.
- root pruningI) process of cutting roots on a field grown tree or pre-digging a root ball to increase the density of root development within the final ball. 2) in tree conservation and preservation. the process of precutting roots behind the line of a planned excavation to prevent tearing and splintering of remaining roots. 3) in tree disease management. severing tree roots to prevent disease transmission through root grafts.
- root rotdecay located in the roots; root decay is usually developed from the bottom up. and crown symptoms may or may not be visible.
- root stockroot or lower part of tree used for plant propagation on which is grafted scion wood to I combine the desirable characteristics of each.
- root zone1) horizon or layer within the soil profile where roots exist. 2) volume of soil containing tree roots. 3) horizontal spread of tree roots from the trunk. Typically the root zone of a tree extends well beyond I the drip line.
- root/shoot ratiorelative proportion of root mass to crown mass.
- rosetteShort. bunchy habit of plant growth
- rotary cutting headsingle-blade or multiple-blade I attachment that rotates to cut or shred vegetation.
- rotation lengthin municipal arboriculture. the length of time between each maintenance pruning for a given geographic area. See cycle.
- round turntwo turns of a line around an object.
- ROWright-of-way
- RPAroot protection area
- RPFRegistered Professional Forester
- RPZroot protection zone