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Arboriculture > Chapter 9: Tree Support and Lightning Protection > Flashcards

Chapter 9: Tree Support and Lightning Protection Flashcards

1
Q

Types of hardware in trees

A

tree cabling, bracing, guying, and propping

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2
Q

What is the point of hardware in trees?

A

to provide the tree with supplemental support by limiting the movement of limbs; may extend the life of the tree or reduce the risk of mechanical failure

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3
Q

codominant stems

A

forked stems nearly the same size in diameter, arising from a common junction and lacking a normal branch union

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4
Q

Purpose of cables installed in trees?

A

to limit movement of limbs with weak branch connections or to support heavy limbs by connecting two or more limbs

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5
Q

Types of hardware for cabling trees?

A

cables, eye bolts, and cabling hardware of different sizes and types

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6
Q

Types of steel cable commonly used in North American for cabling trees?

A
  1. ) 7-strand, common grade cable

2. ) extra-high-strength (EHS) cable

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7
Q

7-strand, common-grade cable

A

steel-cable construction in which seven strands are twisted together in a spiral pattern; used to add supplemental structural support to trees; terminated by wrapping onto itself; relatively malleable (bendable) and easy to work with

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8
Q

extra-high-strength cable

A

EHS; type of 7-strand steel cable, often used to cable trees; stronger but less flexible than common-grade cable; must be terminated with dead-end tree grips; much stronger and less flexible than common-grade cable

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9
Q

aircraft cable

A

steel wire ropes of various constructions designated by the number of strands in the rope and the number of wires in each strand; commonly used in cabling in Australia and New Zealand; 19 strands of galvanized wire; strong and flexible but has limited choices for attachment

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10
Q

anchor hardware

A

hardware to which the cable termination is affixed in a cabling or guying installation; passes through the limb and is fastened to the opposite side; dead-end hardware

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11
Q

eye bolts

A

cable anchor with a closed eye, usually machine threaded; only drop-forged eye bolts are accepted and approved for tree support systems in the United States; stronger than threaded rods with amon-eye nuts

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12
Q

threaded rods

A

metal rod used to support weak sections or crotches of a tree; also called bracing rods; easy to adjust the length for any job

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13
Q

amon-eye nuts

A

specialized nut used in cabling trees that has a large eye for attaching a cable to a threaded rod

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14
Q

Where do you set the washer?

A

directly against the bark or chisel away the bark or drill to countersink the washer against the sapwood (but not int) on trees with very thick bark

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15
Q

lag eye

A

lag-threaded cable anchor with a closed eye; drop-forged anchor with a closed eye

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16
Q

lag hook

A

lag-threaded cable anchor with an open eye (J-shape)

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17
Q

J-hook

A

lag-threaded, drop-forged device in the shape of a J; lag hook

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18
Q

What are standard sizes of J-hooks?

A

5/16-, 3/8-, 1/2-, and 5/8-inch diameter

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19
Q

Purpose of right- and left-handed threads on lag hooks?

A

so the cable will not come unlaid or unwound when the end is twisted into the branch to tension the cable

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20
Q

What do you anchor eye bolts and/or threaded rods with?

A

washers and nuts

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21
Q

Types of washers recommended?

A

heavy-duty, heat-treated round washers (larger in diameter and thicker than standard washers and have a greater metal strength when heat treated)

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22
Q

thimbles

A

in cabling, a device used to form and protect the termination loop in the cable; device used to increase the bend radius of and reduce wear on a rope when attached to hardware; protects the cable from abrasive wear and increases the cable’s bend radius; used when forming an eye in the end of the cable

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23
Q

bend radius

A

radius of an object around which a line passes

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24
Q

eye splice

A

in cabling, a closed termination loop, hand formed in common-grade cable by wrapping the successive strands back upon the standing part to attach the cable to anchor hardware; splice that forms a closed eye or loop

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25
Q

dead-end grip

A

cable-termination devices that must be used to terminate extra-high-strength (EHS) tree support system cable to anchor hardware; may be used with common-grade cable; manufactured spiral-wrap designed to form a termination at the end of a 7-strand EHS cable

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26
Q

What kind of thimble to use?

A

galvanized or stainless-steel, heavy-duty thimbles; used to attach EHS cables to anchor hardware using dead-end grips and pre-warps; reduces wear on the grip hardware

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27
Q

Why do wind conditions matter when installing hardware in trees?

A

excessive wind sway can cause bending and twisting, leading to metal fatigue, which could cause failure; must take wind conditions and potential for twisting into account

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28
Q

come-along

A

portable winching device, using cable or rope to draw two objects closer together; simple arrangement of rope knots and loops to create mechanical advantage; brings two branches closer together

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29
Q

cable grip

A

mechanical device that grasps and holds the cable during installation; grips the cable and helps the arborist pull the cable for tensioning or attaching to anchor hardware

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30
Q

cable aid

A

device used to tighten lags and aid in cable installation; can spread open thimbles, tighten lags, and help wrap dead-end grips onto the cable

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31
Q

What type of equipment to use when drilling holes into a tree?

A

brace and bit or drill

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32
Q

ship auger

A

type of drill bit with an open spiral form; used to drill holes in trees for cable or bracing installation; pulls out shavings from the hole (good for green wood)

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33
Q

Tools in cabling operations

A

come-along, cable grip, cable aid, drills (electric, gasoline-powered, or rechargeable) ship auger, hacksaws, hammers, chisels, mallets, slings, wires, and wire cutters

34
Q

Where to install cables?

A

at least 2/3 the distance from the defective (weak) branch union to the ends of the limbs; more than 2/3 might have branches that are too small (in diameter) for cables to be placed; perpendicular to an imaginary line through the center of the crotch

35
Q

cable stops

A

metal knob that can be affixed to the ends of steel cable strands to terminate a cable installation; protrudes through the drilled hole in a host limb or stem; larger than the hole therefore don’t allow the cable to retreat

36
Q

How tight should cables be?

A

just taut - not slack and not too tight; too tight puts excessive stress on the wood fibers, resulting in more damage at the defect or causing the hardware to pull out; just tight enough

37
Q

simple cable

A

direct cable; one cable between two limbs; most common cable installation

38
Q

triangular combination

A

multiple cable configuration; a diamond with a cable across the middle (two triangles formed)

39
Q

hub-and-spoke system

A

cable configuration that connects multiple leaders while allowing some independent movement; most complex configuration to install (all cables meet at one central point on a stem)

40
Q

box configuration

A

forms a diamond

41
Q

How close can you install cables on the same limb?

A

no closer than the distance equal to the diameter of the limb (or 12 inches whichever is less); never attach in longitudinal alignment with other hardware; only attach one cable to any one anchor

42
Q

What kind of wood can you install anchors into?

A

never install lags in limbs with decay; do not install anchors into decayed areas where the amount of sound wood is less than 30% of the trunk or branch diameter

43
Q

dynamic cable systems

A

any of several cabling systems that utilize nonrigid materials (usually ropes of various constructions) for tree support systems; nonrigid (synthetic fiber) support systems

44
Q

What is an alternative to rigid support systems?

A

dynamic cable systems; allow for more tree sway - more tree movement allows a tree to produce supporting wood where needed, so with time, the tree becomes stronger

45
Q

Cobra

A

German-made dynamic system that connects limbs using a simple splice in polypropylene rope; the ends of the rope feed back into the core, like a Chinese finger-trap device

46
Q

TreeSave

A

U.S.-made dynamic support system; uses hardware similar to that of traditional rigid systems for anchoring the cable in the tree, along with a shock-dampening rope product for the actual “cable)

47
Q

bracing

A

use of steel rod(s) in limbs, leaders, or trunks to provide support for a junction; reinforces weak crotches or strengthen decayed areas; usually used in combination with cabling, not as a substitute

48
Q

lag-threaded rods

A

bracing rod with a coarse thread pattern that is typically screwed into a pre-drilled hole that is smaller in diameter than the anchor or rod; fewer and deeper threads per inch than machine threaded rods

49
Q

machine-threaded rods

A

bracing rod with a fine-thread pattern that is used with a nut and water and installed through a pre-drilled hole that is larger in diameter than the rod

50
Q

Types of steel rods used in tree bracing?

A

lag-threaded rods and machine threaded rods

51
Q

peen

A

act of bending, rounding, or flattening the end of through-hardware for the purpose of preventing the nut from backing off

52
Q

Where to install a single rod used to support a crotch that is not split?

A

the distance of about one to two times the branch diameter above the crotch

53
Q

Benefits of multiple rods?

A

added strength and reinforcement to a split or weak crotch; can be staged to avoid longitudinal alignment which may add to the formation of decay columns in the tree

54
Q

Where to install multiple rods?

A

space rods apart a distance greater than the diameter of the woods being braced (or 12 inches, whichever is less)

55
Q

guying

A

installing a guy and associated anchor; installation of a cable (or rope) between a tree and an external anchor to provide supplemental support and reduce tree movement

56
Q

What to consider when installing tree-to-ground guys?

A

ground anchor must have sufficient strength to support the tree (even under wet conditions)

57
Q

Where to place ground anchors for guys?

A

no closer to the trunk than two-thirds the distance from the ground to the lowest attachment in the tree

58
Q

Where to install guys on an anchor tree?

A

on the lower half of the trunk; preferably greater than 7 ft from the ground if there is pedestrian traffic under the guy or greater than 14 ft if there is vehicular traffic

59
Q

Where to install guys on the tree to be supported?

A

above the midpoint, preferably at about 2/3 the height of the tree

60
Q

How to protect tree-to-ground guys?

A

clearly marked and protected from inadvertent contact; advisable to place a mulch ring around the ground attachment point to avoid lawn mower damage

61
Q

propping

A

rigid brace, acting in compression to support a tree, tree branch, or utility pole; prop pole; installation of rigid structures between the ground and a branch or trunk to provide support to keep the branch or leaning trunk off of the ground or a structure

62
Q

What kind of branches require props?

A

under branches that are nearly horizontal or downward growing

63
Q

What are props made of?

A

wood, steel, concrete, or other materials; must have sufficient strength to support the expected load

64
Q

side flash

A

phenomenon of a lightning strike leaving its current path and “jumping” to reach a better-ground conductor

65
Q

step voltage

A

significant difference in electrical potential, which can lead to electrocution if contacted simultaneously

66
Q

Where does lightning exit an unprotected tree?

A

through the roots and dissipates into the soil

67
Q

Purpose of lightning protection systems installed in trees?

A

reduces the risk of damage to trees by lightning strikes; protects trees by providing an alternate path (of lower resistance) to the ground instead of lightning passing down a tree, a conductor is used to take the lightning from the top of the tree down to to the ground

68
Q

How many trees struck by lightning carry no visible injuries?

A

20%; trees presenting no immediate sign of lightning damage might enclose a damaged vascular system and are still prone to increased stress, inefficient defense systems, and pest attacks

69
Q

What do lightning strikes do to trees?

A

can destroy the whole tree at once or may cause significant structural damage that creates a hazard requiring removal of the tree; disrupts the tree’s nutrient and water flow long term; might serve as an “open door” for borers, decay, and future structural degradation

70
Q

What affects the extent of damage lightning causes?

A

bark thickness, wood porosity, and moisture content

71
Q

What trees to consider for lightning protection?

A

trees close to houses or other buildings but much taller than buildings and trees, or trees of historic interest and high economic value; trees in recreational areas, parks, and golf courses are more prone to lightning strikes; tallest trees in geographic regions where lightning is common

72
Q

What is in a lightning protection system?

A

copper conductor that extends from the top of the tree, down the main branches and trunk, and out, into the soil where it is grounded; air terminal, conductors, and ground terminal

73
Q

air terminal

A

uppermost point of a tree lightning protection system; top end intended to intercept the lightning strike; should be installed as high on the tree as possible

74
Q

conductors

A

blunt tip; metal wires, cables, and bus bar used for carrying electric current; conductors may be solid or stranded (i.e., built up by an assembly of smaller, solid conductors); copper cable connected to the air terminal that run down a major branch or the trunk

75
Q

ground terminal

A

either a ground rod or ground plate; used in grounding a tree lightning protection system; provides electrical contact with the ground; consist of ground conductors, ground rots or plates, and all other associated connectors

76
Q

How should the main conductor/primary conductor be connected to the tree in lightning protection systems?

A

path should follow the natural shape of the tree, avoiding sharp bends, kinks, and crotches; attached at regular intervals (usually 3-6 feet) using approved conductor attachments; primary conductor should run straight down the trunk on the side of the tree toward the ground site

77
Q

How many conductors is required in tree in lightning protection systems?

A

one - if crown radius is smaller than 35 ft

one plus secondary conductors - recommended if has greater spread radius that 35 ft

78
Q

branch conductors

A

secondary conductors that connect to the main conductor on the trunk

79
Q

ground rod

A

metal rod used in grounding a tree lightning protection system

80
Q

How many ground rods should be installed in lightning protection systems?

A

2 - if dry, sandy, or gravel/rocky soil

81
Q

Where should ground terminals be installed

A

not within 2 ft of a structures foundation and not within 2 feet of other underground installations; trench as close to the trunk as practical and at least 8 in deep unless restricted by roots, rocks, or impenetrable soil (avoid damaging roots greater than 2 in in diameter)

Arboriculture (16 decks)

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