Glossary of Tree Climbing & Related Terms

Facilitator helping young climber with climb, orange helmet

Note:  This is a living document, please e-mail your recommendations for additions or revisions to GOTC.


Aeration: Breaking up of soil matter to allow for more air to penetrate down.

Anchor (point): (also see Tie-in point or TIP): The spot in a tree over which a climbing rope is either looped or tied off.

Arboriculture: Cultivation and caring for trees and shrubs.

Arborist rope:  Standard for tree climbing due to its polyester outer sheath, which is more temperature resistant that the nylon sheaths of rock climbing static or dynamic ropes.

Ascenders: Mechanical device(s) used for going up a rope, usually in SRT.


Biodiversity: Short for biological diversity, includes the variety of species, genetic diversity within a species, and the diversity of ecosystems within a recognizable area.

Biomass: Organic material.

Bitter end: A stopper knot tied near the standing end on a double rope system to prevent the climber from descending off the end, thereby disconnecting the doubled rope and falling.

Branch: Part of a tree growing out from the trunk, leader, or other main limbs.

Branch collar: Junction between branch and another branch, trunk or leader, often a ring of wood tissue.

Branch route: A climbing route that ascends or descends away from the trunk.

Bridge: In the doubled rope system, that portion of the rope that connects the “up” rope (working part) with the “down rope” (standing part).


Cambium: The sensitive, thin layer of living, dividing cells under the bark of trees.

Cambium saver: Device used to protect the sensitive tissue of a tree from the abrading effects of a moving climbing rope. The two basic styles are hoses/tubes which rest on top of the branch or in a crotch and through which the rope slides; and false crotches, which are draped over the anchor point and have two rings hanging below, through which the climbing rope passes.

Canker: Dead or diseased trunk, ofter with missing bark. A climbing consideration.

Canopy: The uppermost parts of trees in a forest or grove, forming a continuous cover.

Canopy shyness: The crown of one tree retreating from the encroaching crown of another due perhaps to either shading or abrading effects.

Carabiner: A coupling link with a hinged gate, often spring loaded. Carabiners come in many shapes such as pear, oval, “D”, and styles such as auto-locking, screw-gate closure, and accessory (non-life support).

Champion tree: A tree judged the largest of its species in a certain area, using a point system combining the diameter at breast height (DBH), the tree height, and the average crown spread.

Climax community: A plant community at the final stage of its successional sequence.

Clip-in point: Place on the harness where a rope is attached by means of a carabiner or other device.

Community: Species living and interacting in an area.

Compost: Decayed organic material that acts or can be used as fertilizer.

Conifer: Tree or plant bearing a cone, and whose leaves are either needles or scales.   

Coniferous: Referring to the category of conifer trees.

Crotch: The fork formed at connections between branches, leaders, and trunk.

Crown: The branching, spreading, leafing upper part of a tree.


Deadwood: (n) nonliving tree tissue, such as dead branches, twigs, etc – (v) the act of removing dead wood from a tree.

Deciduous: Category of trees that shed their leaves annually. Also known as broadleaf trees or hardwoods.

Descenders: Mechanical device(s) used for coming down a rope, usually in SRT.

Delta screw link: Triangular shaped coupling device with a screw down closure often used for harness clip-in points, whose principal advantage is being equally strong in all three directions, proving more omni-directional loading flexibility.

Disturbance: Natural or artificial occurrences that affect the normal dynamics, functioning, or successional state of a patch, landscape, or ecosystem.

Double(d) Rope Technique – DdRT or DRT: Climbing technique using one rope looped over a branch or crotch, in order to approach a 2-to-1 strength advantage and utilize a single system for both ascent and descent.

Drip-line: Circumference of the crown, as outlined on the ground.


Ecosystem: The sum of interactions between a community of species and the non-living components of its environment, such as temperature, soils, water, and elevation.

Ecotone: Area of transition, edge, or overlap between at least two distinct ecosystems.

Emergent tree: A tree whose height rises above those surrounding it, providing unobstructed vistas.

Endangered species: A species or subspecies that is in jeopardy of becoming extinct.

Endemic species: A species found nowhere else in the world.

Epiphyte: A non-parasitic plant growing on another plant or tree.

Evergreen: Plant or tree that keeps its leaves throughout the year, or sheds leaves after having first grown new ones.

F – G

False crotch: See cambium saver.

Friction hitch:  Hitch whose design and physics allows the climber to ascend, descend, or remain in place. Often the main climbing hitch, e.g., Blake’s hitch.

Facilitated climb: Climb where facilitator remains on the ground helping climbers into and out of equipment, managing climbers activities aloft, and being responsible for overall safety.

Facilitator: Person who conducts a group, program, or similar climb.

Flush cut: Branch pruning technique whereby the branch collar is removed along with the branch, resulting in increased risk to the tree from disease, decay, or physical stress.

Grove: A small assemblage of trees.  In tree climbing, the physical site of climbing activities. Also used to describe a community or group of tree climbers, or a recreational tree climbing business or school.

Growth ring: Delineated annual addition of wood, whose width and characteristics reflect growing conditions.

Guided climb: Climb in which all climbers, including the leader or lead climber, leave the ground and climb together. 

H – K

Habitat: Physical conditions that determine where organisms live and get the food, water, shelter and living space they need to survive.

Hand: The feel of the rope.

Hazard tree: Tree posing a significant risk to people or property.

Heartwood: The densest, inner section of the tree trunk, surrounding the pith/core.

Hitch: A knot that fastens a rope to another rope or to something else.

Indigenous species: Native to the area; not introduced, exotic, or invasive.

Instructor: Person who teaches others climbing, facilitator or instructor skills.

Knot: Interlacing of material in one or more ropes to either secure or form a lump.

L – O

Lateral: A branch growing out from the side of another branch, leader, or trunk.

Lead climber: The climber who proceeds first and is responsible for either setting lines or inspecting conditions above.

Leader (tree): A major upright trunk portion.

Leaner: A tree that deviates significantly from vertical.  A climbing consideration, depending on species, degree of lean, and other inspection factors such as root upheaval.

Limb: Similar to branch, but generally more substantial.

Mature tree: Tree that has attained the majority of its full crown height and spread, or a significant portion of its expected life span.

Mulch: Material such as wood chips, bark chips, or grass clippings spread over the ground or around a tree or plant to aid in soil moisture retention, reduced soil compaction, or otherwise benefit the tree, plant, or soil.

Niche: The function, opportunity, or “job” available to a living thing in an ecosystem.

P – R

Phloem: Wood tissue layer that carries photosynthate sugars (the product of photosynthesis) and other nutrients down from the leaves.

Photosynthesis: The process by which green plants manufacture simple sugars and oxygen from carbon dioxide and water, in the presence of sunlight.

Pioneer species: Early successional species that are often first to colonize habitats not yet suitable for other species.

Pitch: 1) The act of throwing (v); or the throw itself (n), of a line or rope into or within a tree. 2) Tree or pine resin.

Pith: The center core of the wood, surrounded by the heartwood.

Pollination: Transfer of pollen from the male part to the female portion of a plant.

Pollinator: An organism that pollinates flowers.

Pruning: Purposeful removing of branches, twigs, leaves, etc.

Restoration:  As a management strategy, the process of attempting to reestablish the original condition of a degraded environment.

Recreational Tree Climbing (RTC): Climbing for purposes other than commercial or tree care/work. Climbing activities that focus on experiencing the tree or the relationship of the climber to the tree, forest, or nature. 

Root collar: Above-ground junction between root and trunk, often flared. 


Sapwood: Most recently added wood layer, between heartwood and bark.

Shout calls/commands/signals: Universal RTC language called out to others in or near the tree as shorthand communication concerning dangers or conditions.  E.g. “Headache!” to warn of a falling object. 

Single Rope Technique – SRT: Climbing technique using a single rope, usually with one end either cinched around a branch, or tied off to the trunk/base of a tree.  Has the advantage of a 1:1 strength to vertical movement, and the use of most of the length of the rope for elevation gain.

Soil compaction: Compression of soil material from surface pressures of heavy mechanical or human use, resulting in a reduction in aeration and moisture infiltration.

Species: Populations of individuals that look and behave similarly, and are able to breed and produce fertile offspring under natural conditions.

Split-tail: Short accessory line between harness and main climbing rope incorporating the climbing hitch in order to reduce friction and wear on the main climbing rope along with other benefits.

Standing end/part: The non-working end of the rope, or the part below or moving down in DdRT (the “Down” rope).

Stopper knot: Inline knot tied near the tail to prevent another knot or hitch from moving or rolling off the tail.

Succession: The natural process by which plant communities replace previous ones over time.

Sucker: Shoot arising from the base of a tree or from an underground root.

Sustainability: Maintenance and use of ecosystems or human systems to ensure prolonged functioning of natural processes, preservation and non-depletion of resources.

Super System:  A modification utilizing pulley(s) and a tripled rope, thereby approaching a 3:1 strength advantage to climbers.

Switchover: Setting a new anchor within the tree once aloft, usually using the standing end of the climbing rope, for the purpose of proceeding up, down, or laterally.

Symbiosis: Literally “living together”; two organisms living closely associated for extended periods of time, with at least one species benefiting from the relationship.


Tail: Either end of a length of rope.

Tame tree: A tree that has been previously climbed and has received pruning or deadwooding attention.

Thinning: Removal of a portion, or a limited number, of the trees in a forested area, usually of varying sizes, ages, and species as part of a forest management plan.

Threatened species: Species or subspecies in jeopardy of becoming endangered.

Throw line: Thin line used for tree entry and switchovers, used to connect to and set main climbing rope or stronger throw line.

Throw weight/bag/ball: Weight tied to the end of the throw line and thrown over a branch or into a crotch for the purposes of setting a climbing rope.

Tie-in-point (TIP): (See Anchor) (Also used by some to refer to the clip-in point, the place on the harness where a rope is attached by means of a carabiner or other device.)

Traverse: A switchover between two trees.

Tree entry: The initial pitch or throw into the tree from the ground using a throw line, climbing rope, or other means.

Tree-line: The transitional zone or edge (see Ecotone) between forest and alpine tundra. Also known as timberline.

Trunk route: A climbing route that ascends or descends in close proximity to the trunk.

U – Z

Widow-maker: A hanging or hung-up branch or limb in danger of falling and potentially causing serious harm.

Wild tree: A tree that has not been previously climbed, and has not received pruning or deadwooding attention.

Working/running end/part: That end of the rope that contains the friction hitch in DdRT, or that part of the rope that leads up or above the climber (the “Up” rope).

Wound: Break or opening in the bark, caused by cutting, abrasion, insectology, disease, etc. A climbing consideration.

Xeriscape: Sustainable landscaping practice, mimicking natural ecosystems by utilizing native species and local, non-living physical attributes, resulting in increased biodiversity and reduced input needs.

Xylem: Tissue in trees and plants which transports water and salts upwards and provides structural support. 

Yo-Yo system:  A climbing system on a single rope utilizing accessory line and mechanical assist devices near the climber to achieve some of the benefits of a doubled rope system.