1. Doubled Rope Technique (DdRT) – The traditional, “old-school” tree climbing system, wherein the climber’s line runs up from the ground, through a friction hitch (or mechanical device) at the saddle, then continues up and over a branch union (tie-in point), then back down to the climber where it terminates at the saddle. This system forms an adjustable loop that can be made larger or smaller, thus allowing the climber to move towards or away from the tie-in point. Note that the entire length of rope is moving as the climber ascends or descends, making friction management an important concern.
2. Moving Rope System (MRS) – another name for a DdRT system.
3. Stationary Rope Technique (SRT) – modern style climbing system adapted from other rope-based disciplines, wherein the climber’s line is run up through a branch union (tie-in point), and either affixed to it directly, or run back to the ground where it is tied off. The climber is attached to the line by a friction hitch (or mechanical device). In this setup, the climber can ascend and descend with consistent friction, as the rope remains stationary, i.e. the climber is moving along a fixed line.
4. Stationary Rope System (SRS) – another name for an SRT system.
5. Work Positioning System – allows us to climb and access trees in relative safety. This includes rope(s), the harness, the climbing system, and all hardware in the system. All components of our work positioning system are engineered, i.e. rated components (we know their strength).
6. PPE/Personal Protective Equipment – the most basic safety gear that we use to prevent injury. Examples include: helmet, safety glasses, work boots, protective trousers, gloves, etc.
7. Anchor – the branch unions and stems in a tree that support our ropes, which in turn support our bodyweight. These are also called tie-in points or suspension points. In tree climbing, our anchor points are organic and non-rated, meaning that we never really know how much load they can handle. As such, anchor points are selected very carefully, using experience, good judgement and patience.
8. Belay – controlling the amount of slack between the anchor and the climber. Slack is necessary for movement in your work positioning system, but slack is also dangerous and exposes a climber to a fall. As long as a climber stays below their anchor point and keeps the slack out of their system, then when they slip they are caught immediately by the rope and they take a swing. If they climb above their anchor point or they have slack in their system, then when they slip they can take a fall. In rock climbing, the belay is provided by a climbing partner, who manually pays out or takes in slack as required. In tree climbing, we use what are called self-belay systems, where the climber controls the amount of slack in the system by themselves.
9. Proprioception – the sense of self-movement and body position in three-dimensional space, achieved through agility, balance, and coordination. Also referred to as kinaesthesia. Proprioception is fundamentally personal and typically absent from conscious perception.
10. “Rated” component – any engineered and manufactured component used as life safety gear for climbing must be stamped with a strength rating. This rating tells the user the Minimum Breaking Strength (MBS) of that component. MBS for climbing gear is measured in Kilonewtons (kN), as opposed to kilograms or pounds. Most rated climbing gear sold for occupational, i.e. professional use, as opposed to recreational use, is required to have an MBS of 23 kN, which is just over 5000 lbf, just over 2300 kgf.
11. “Non-rated” component – this designation could refer to any piece of equipment that is either of unknown strength, or is not rated sufficiently strong to meet our required minimums.
12. Minimum Breaking Strength (MBS), aka Tensile strength : obtained through testing, MBS is the average breaking strength of a piece of equipment when pulled to failure under controlled conditions. Tensile strength (MBS) is usually quoted in kN.
13. Kilonewton (kN) – the SI unit of force. 1 kN is equivalent to 102 kgf or 225 lbf.
14. Minimum strength: as defined by safety legislation and regulations, life safety gear for occupational use is required to have a minimum tensile strength of 5000 lb (usually rounded to 23 kN). See “rated component” above.
15. Working Load Limit (WLL): expressed as a fraction of the tensile strength, this is the maximum load that the equipment is rated for over a large number of cycles. Standards are: rigging gear 5:1, climbing gear 10:1. For example, if a rigging line is rated for 5000 lb and the working load limit is 5:1, that means you can consistently load it with 1/5 of its tensile strength (i.e. 1000 lb). For a climbing line rated at 5000 lb, you can consistently load it with 1/10 of its tensile strength (i.e. 500 lb).
16. Cycles to Failure: Ropes and slings can only be exposed to heavy loads so many times before they eventually fail. Adherence to WLL guidelines will ensure long life for your equipment, this is why it is so important to know the history of your gear.
17. Static Rope: very low stretch (0.5-1.5% range). Used sometimes in srt climbing and in rigging ziplines/speedlines.
18. Semi-static Rope: low stretch (1.5-4% range). This is standard arborist rope used for climbing and rigging.
19. Dynamic Rope: very high stretch (5-20% range). Used in mountain climbing to catch a lead climber during a fall to minimize injury.
20. Tie-In Point / Suspension Point – also known as anchor, these are the branch unions or points in the tree that support a climber’s rope(s). The tie-in point is an organic, i.e. non-rated, component of the work positioning system that keeps a climber from falling. As such, they are selected very carefully, using good judgement and patience.
21. Canopy Anchor – a type of tie-in for SRT climbing systems where the rope is isolated on a branch union or point in the tree and affixed at that point, either using a piece of hardware or by tying a knot. This configuration keeps the anchor inaccessible to people on the ground, as well as ensuring that the tie-in point only experiences the load of the climber’s weight, not some multiple of that weight.
22. Basal Anchor (Base Tie) – a type of tie-in for SRT climbing systems where the rope is run through one or more branch unions in the tree, then run back down to the ground, where it is anchored using a piece of hardware or by tying a knot. This configuration keeps the anchor accessible to people on the ground, as well as multiplying the load of the climber’s weight at the tie-in point through mechanical advantage.
23. Friction – the force resisting the relative motion of solid surfaces sliding against each other. Friction produces heat which can damage both ropes/hardware as well as tree bark. Friction management is a key component to many tree climbing systems, especially DdRT systems.
24. Isolated – we say that a rope is “isolated” in a branch union (crotch) when the rope runs up from the ground, over the branch, and back down to the ground, with both legs of the rope following the exact same path, such that no branches are in between either leg of rope. In other words, you could tie both legs of rope together with a running knot, such as a running bowline, and that knot could be pulled up all the way to the branch where it would be tied off to that branch only.
Please note that this list is to be considered perpetually incomplete. It is constantly being updated, added to, and corrected.
*** See also: Language of the Ropes: Tree Work