DESCRIPTION OF ARBORIST METHODS FOR FOREST CANOPY ACCESS AND MOVEMENT

14 Pages·1994·0.33 MB·

by  Dial, Roman

Selbyana 15(2): 24-37
DESCRIPTION OF ARBORIST METHODS FOR
FOREST CANOPY ACCESS AND MOVEMENT
ROMAN DIAL 1,2
Department of Biological Sciences, Stanford University, Stanford, California 94305
S. CARL TOBIN3
Department of Biology, Northern Arizona University, Flagstaff, Arizona 86011
ABSTRACT. Arborist methods and equipment are described for climbing trees. Equipment lists and
sources are provided and techniques illustrated. Many arborist methods of non-injurious access, ascent,
within-crown movement, and descent are applicable to certain tropical forest situations. Arborist methods
of access are most appropriate for trees with lowest limbs below 25 m above ground level; however, methods
of ascent and movement within crowns are useful for any trees, including those with lowest limbs above
25 m that can support a climber's weight. Problems presented by limbs with heavy epiphyte loads are
addr~ssed. The advantages of arborist techniques include low cost of equipment specifically designed for
climbing trees' increased safety using ropes manufactured for tree climbing; greater mobility and availability
of ropes for re:use within the crown; and minimum exertion for ascent and descent using the limb as pulley.
INTRODUCTION lands (Puerto Rico to Grenada) between 100 and
600 m. In 1989, Hurricane Hugo severely dam
Canopy biology has grown expansively over aged one of the forests we studied. This distur
the past two decades (e.g., compare Perry 1978 bance resulted in abundant undergrowth <3 m
with Moffett 1993), particularly in the tropics. high of Piper, a Urera nettle, and Cecropia. The
With this growth, a diversity of tree access meth other forest was relatively undisturbed with es
ods has followed, but with little documentation sentially no undergrowth < 3 m high. In the dis
of technique and method (but see Perry 1981, turbed forest Prestoea palms and Cecropia dom
Whitacre 1981, Mitchell 1982, Mori 1984, Nad
inated the understory. Neither forest supported
kami 1988b, Munn 1991, Tucker & Powell 1991 , many epiphytes and each was structurally sim
Wilson 1991, Lowman & Moffett 1993, Moffett pler and shorter than mainland tropical rain for
1993, Moffett & Lowman 1994). Here we present ests of similar climate.
methods of access, ascent, descent and traverse Due to the requirements of experimental ma
used by professional and recreational arborists nipulations within individual tree crowns, we re
(as described, e.g., in Tree Climbers Intemation
quired tree climbing methods that allowed free
a11987, New Tribe 1993), but previously unre
dom of movement within crowns, comfort, and
ported in the scientific literature.
safety. We found the best methods applied tra
Many of these arborist methods were used in
ditional arborist techniques using a blend of
Puerto Rican rain forest canopy over a nine
equipment from mountaineering (ascenders, de
month period during which over 2,000 man scending devices, carabiners, etriers, slings) and
hours were spent executing a canopy-level ex arborist (ropes, harnesses, throw bags, and saws)
closure experiment, measuring the abundance and sources.
transport of aerial arthropods, and elucidating a The purpose of this paper is to describe, illus
canopy food web. Thirty trees between 20 and trate, and provide source information for equip
30 m high were climbed and re-climbed. ment and techniques allowing access, ascent, lat
The techniques were applied in two lower eral mobility, and descent that are safe for the
montane, second-growth, tabonuco forests. Ta
scientist and non-injurious for the tree. Partial
bonuco forest is named for its dominant tree applications and limitations oft he techniques are
species, the broad-leaved evergreen tabonuco tree also discussed, particularly with respect to very
(Dacryodes excelsa), and grows on the windward
tall trees and to trees with heavy epiphyte loads.
sides of the mountainous eastern Caribbean Is-
Solutions from the recreational tree climbing
community address some of these limitations.
Our hope is that other canopy scientists will
Corresponding author. find these techniques and equipment appropriate
I
2 Present address: Alaska Pacific University, 4101 to their own use and that canopy science will be
University Drive, Anchorage, Alaska 99508. more productive and safer as a result. For those
3 Present address: Utah Valley State College, 800 who have never climbed trees before, these tech
West 1200 South, Orem, Utah 84058. niques provide an ideal starting point. For those
24
1994] DIAL & TOBIN: FOREST CANOPY ACCESS 25
who have been climbing for a decade or more, tall trees (30-40 m) (Tucker & Powell 1991; Tim
we hope that this paper opens up new options Laman pers. comm.).
and advantages that can be incorporated into We used a crossbow to access the canopy of
well-proven systems. two of 30 trees we sampled. We also prussiked
(that is, to wrap two prussik lines directly around
the trunk, then alternately move them upwards
MATERIALS AND METHODS to ascend) 20 m directly up the bole of one tree
(prussik slings encircling the 48 cm DBH trunk).
Professional tree climbing in the U.S. is at least In this case, as with tree climbing spikes or Swiss
75 yr old, as documented in an out-of-print cat tree grippers (Mori 1984), access and ascent are
alog of arborist equipment provided by Sierra simultaneous. The method was slow, laborious,
Morino Mercantile (Mountain View, California; and uncomfortable; however, it may prove suit
see Appendix). Individual arborists climb sev able for palms.
eral new trees daily and their work requires ex On another occasion we established a 70 m
tensive within-tree movement that is both safe tyrolean traverse (a rope line affixed to two trees
and inexpensive. For a $200 investment in ar that was then traversed using harness and as
borist equipment and using arborist techniques, cenders) through the forest to access seven trees
it is quite possible to safely climb 30 m trees adjacent to the traverse line. In this case each
using only a 50 m rope and a harness. With an tree was accessed by throwing the arborist's throw
other rope and a 4 m pole saw, it is possible to bag (see below) or a climb line into the trees
traverse from one tree to another without the adjacent to the traverse. The tyrolean method
need to descend to the ground. The ropes used was efficient, although somewhat dangerous and
are designed for tree climbing and the harnesses uncomfortable.
for sitting and dangling. These advantages of price The safest and most efficient method of access
and applicability should appeal to budget- and was the arborist's weighted throw bag (FIGURE
safety-conscious ecologists. 1). We used the throw bag in 27 of 30 trees, if
not for initial access, then for secondary limb
Access access. The throw bag (also called throw weight)
is a lead shot filled bag weighing about 0.5 kg. It
The most time-consuming stage ofa tree climb is attached to one end of a 50 m x 4 or 5 mm
is often initial access. We define access as the first diameter polypropylene throw line. The throw
contact with the canopy that will then allow oc line is first flaked-out on the ground so that the
cupation of the crown. Once initial access is ac end with the throw bag is on top of the coil. Then
complished, either by arborist methods de the climber takes a neat hand coil of the throw
scribed here or by others, the arborist techniques line together with the throw bag and throws un
of ascent and within canopy movement can be derhand over the highest limb reachable (10-25
applied. m).
As Perry (1978,1981) has described, a cross If the tree of interest has no branches at this
bow may send an initial line over a limb. Our height or lower, a neighboring tree may be the
experience with crossbows has been unsatisfac key (see below); or devices such as spikes, cross
tory. The fishing line attached to the bolt (cross bow (Perry 1978), longbow (Tucker & Powell
bow arrow) is difficult to flake-out (to lay down 1991), or slingshot (Nadkami 1988b) can be em
so that line feeds out smoothly) without becom ployed. It may require upwards of 1 hr to get the
ing tangled. Use of a variety of fishing reels, in line over a 20 m limb; however, once accom
cluding a model specifically designed for the plished, access is nearly guaranteed, unlike a suc
crossbow, increases drag on the line and damp cessful monofilament shot which may break as
ens bolt flight. Without much control over where a successive line is pulled up. We were unable
the bolt goes after clearing the limb, tangles and to obtain a slingshot during our Puerto Rican
bolt loss are common. Stock bolts are too light work; however, those familiar with both throw
to pull the line down to the ground; weighted bags and slingshots have found that the slingshot
bolts frequently break the bow string. is more efficient for rigging lines between 15 and
Compound bows with saltwater fishing reels 25 m and that throw bags are faster for the lower
and 30 pound monofilament line are used by trees (T. Laman pers. comm.).
recreational arborists to access very tall conifers There are three clear limitations to the throw
in the Pacific Northwest of the United States. bag technique of access. The first is limb height
These climbers shoot solid, fletchless (no feath above ground. As mentioned, most arborists can
ers), fiberglass arrows with rubber target tips to throw only to limbs approximately 20 m up.
40 m (Tom Ness pers. comm.). Longbows also Some, with the recent technique and equipment
have served canopy biologists well in accessing developments of New Tribe (Grants Pass, Ore-
26 SELBYANA [Vo lurne 15(2)
Grip krlOt
3. One version of a utility harness used by arborists
to work in trees. Point A is the rope attachment point.
Some harnesses have a permanent metal ring attached
to this strap. Point B is a fixed ring suitable for the
Throw Bat hitch knot (FIGURE 9) of a flip line which then clips
with a snap link to C for use as shown in FIGURE 7.
r To
Bro..n.c~
'\
RunhingLirLB
Arborlst
Knot
FIGURES 1-4. Important arborist equipment. 1. A
throw bag with attachment knot and grip knot (over
hand knot). The grip knot is 0.5 to 1.0 m from the
throw bag. Dimensions of the throw bag are approxi
mately lOx 6 cm. A bowline works as a suitable
attachment knot.
"
[ J
o
)
Clipto
............
Hoxness
Coil
2. Rope cross sections. Cross section of typical
mountaineering rope on left and arborist climb line on 4. Left knot is the double figure-8 suitable for at
right. The shaded regions show the core of each rope; tachment to harness via carabiners. Right knot shows
the sheath area is unshaded. The sheath protects against path of tail in tying the arborist knot and the end knot.
abrasion and the core gives the rope dynamic strength The end knot (to the right of arborist knot, at tail end
for holding falls. In general, there is little opportunity of rope) is necessary for the proper friction functioning
for falls while climbing trees using the techniques de of the arborist knot. All knots are shown in a loose
scribed here; instead, high abrasion resistance is re configuration. Reach and running lines are described
quired. in the text.
1994] DIAL & TOBIN: FOREST CANOPY ACCESS 27
gon; see Appendix), are able to throw to 25 m Bedford, Massachusetts) are the most popular.
(T. Ness pers. comm.). To overcome this limi Unlike nylon mountain climbing ropes, which
tation, arborists climb a nearby tree (called a act as dynamic springs manufactured to with
transfer tree, see section on moving from tree to stand leader falls, polyester arborist ropes are
tree below) and throw from there. For the tallest, static lines with thick sheaths manufactured to
stands of diptocarps of Southeast Asia, this withstand friction and UV degradation. Static
method may not be ideal for initial access (T. mountain climbing ropes devote less than 20%
Laman pers. comm.); however, it still affords of their material diameter to withstanding fric
upward motion within many crowns where the tion, whereas climb lines devote nearly 70% of
branches are less than 20 m apart. For the largest their diameter to rope protection from wear.
trees, an initial access using a compound or long Thus, while mountaineering ropes typically de
bow (Tucker & Powell 1991) can place the tree vote 35% oftheir cross-sectional area to abrasion
climber in position to move further upward using resistance, over 90% of the cross-sectional area
the throw bag for subsequent movements. of an arborist's climb line is devoted to abrasion
Oxman (1993) reports on an arborist ascent of resistance (FIGURE 2). Moreover, the handling
a 100 m redwood tree in California. The ascent characteristics of kern mantle ropes do not allow
required mixed access techniques: spikes and flip for use of the arborist knot. We advocate that
line to access the initial transfer tree to 70 m (the only those ropes designed for tree climbing should
100 m target tree was too big in diameter for the be used for climbing trees.
spike and flip line technique apparently), fol We do not coil our climbing ropes. Instead we
lowed by tying in with arborist rope and knot feed them into rope bags, such as nylon sleeping
(discussed below) and a pendulum swing to the bag stuff sacks. This method is faster than coiling
next transfer tree 5 m away. which was climbed and completely eliminates tangles when with
for some distance before transferring into the drawing the rope. To withdraw the rope, simply
final 100 m tree. Thus, two transfer trees, spikes, grasp the final end inserted into the bag (usually
flip line, and arborist rope methods were used to marked by the double figure-8 knot) and pull out
climb a 100 m tree. the line as needed. Ropes are more easily packed
The second limitation concerns undergrowth and protected this way. One further advantage
and understory. If there is too much under is apparent when dropping ropes for descents. By
growth, a small area may be cleared to provide leaving the rope in the bag and then dropping
for throwing. In the Cecropia and Piper brush of the bag, tangles in branches are prevented.
Puerto Rico, we cut a 3 m radius circle with a Once tied to the climb line, the throw line is
machete. The throw line sometimes tangled with pulled until the climb line passes over the access
Jianas and required a change in angle of throw. limb and down to the ground. The climb line
When stuck, a quick tug was sufficient in all cases and throw line are then untied. The access limb
(except one) to retrieve it. A second bag might is tested by grabbing the climb lines (both sides)
be a valuable addition to the kit in case the first and dangling, bouncing, swinging, and jerking.
gets permanently wedged. We used non-palm un
derstory trees to access taller neighbors, and nev
er found the understory problematic, although it Ascent
could be in other forest types. Puerto Rico's ta
bonuco forests are fairly clean of epiphytes and At this point, two different arborist techniques
lianas; thus, problems with the throw bag were can be applied for ascent. Both will allow for re
minimal. use of the rope within the tree climbed; that is,
The third limitation is that palm trees are not neither technique requires fixing the rope to
accessible using this technique, since the throw ground level anchors (for example, a nearby tree
line would probably lodge in the palm fronds. trunk). The advantage of having the rope avail
Moreover, the methods of ascent and movement able for re-use in the tree is that the climber can
described below would prove unsuitable for palm move up as high as desired or possible.
crowns and their fronds. The first technique, the traditional arborist
Once the throw line is passed over the limb technique, uUizes the access branch as a pulley.
and the throw bag retrieved, the arborist ties the The benefit is reduced exertion during ascent.
50 m x 12.5 mm diameter climb line to the (An analogy would be carrying a 75 kg load across
throw line. Several brands of braided polyester a room: while it is possible to carry it in one load,
ropes are specifically designed and manufactured and while two or three loads might require more
for tree climbing at two-thirds to half the price total kinetic energy, it is easier to move it in 3
of mountain climbing ropes. Twelve-strand Ar trips of 25 kg each.) The disadvantage is that a
borplex of Samson (Seattle, Washington) and 16- tree with thin bark might suffer rope abrasion
strand Safety Blue of New England Ropes (New damage on the top of the limb (T. Ness, T. La-
28 SELBYANA [Volume 15(2)
A
A 3.
FIGURES 5-9. The traditional arborist method of ascent.
FIGURE 5. In this overall view, Limb A is the lowest limb and serves as a stance. A throw bag and throw line
were used to place a climb line over limb B. In Panel I the arborist uses an arborist knot to ascend. His first
destination is limb A where he can stop, as in Panel 2, and prepare to access limb C. Limb C is accessed by
tying a knot (monkey's fist) on the end of the rope opposite to harness attachment. This end is free because the
arborist method does not require the rope to be anchored to the ground. Because the climb line is only attached
to the arborist, the opposite end is available for accessing the next limb, C, as shown in Panel 3. Once the climb
line is passed over limb C, the arborist can tie in, attach arborist knot or ascenders, and then detach from the
1994] DIAL & TOBIN: FOREST CANOPY ACCESS 29
FIGURE 6. The arborist knot is used by grasping the running line below the knot (Panel I). Then the arborist
pulls down on the running line (Panel 2), simultaneously pulling the arborist up. Holding tight with the lower
arm below the knot, the arborist uses his upper hand to grasp the knot. now no longer under tension. and slides
the knot up to full reach (Panel 3). The arborist sits back in the harness, puts tension on the tail, and engages
the knot about the running line; this leaves the hands free for work (Panel 4) or rest. The process is repeated as
necessary. A single mechanical ascender could replace the knot; the sequ.ence and method of ascent would remain
identical.
man pers. comm.). While we never had a prob more than conventional mountaineering tech
lem with this, each of our trees was only climbed niques. This method is particularly well suited
on two successive days once a month for nine for limbs with heavy epiphyte burdens (T. Ness
months. Also, if the epiphyte load is heavy, the pers. comm.).
rope will cut into the epiphytes and possibly seize,
and debris may rain down as the rope moves Traditional Arborist Ascent
through the organic matter (T. Laman pers.
comm.). If the limb passes the safety test, the arborist
The second ascent technique, the recreational ties into the utility-harness (FIGURE 3) approxi
arborist technique, requires more effort, but no mately 2-2.5 m from either end of the rope. The
~
climb line used for ascent to limb B (Panel 4). This detachment from limb B should only occur after securing
with a second safety rope such as a daisy rope, flip line, or sling. The backup equipment should be attached
only after limb C has been accessed, its climb line attached to the climber, and its strength thoroughly tested.
In this way. a rope shorter than the tree can be used to ascend the entire tree. Alternatively, two ropes can be
carried and their use alternated. If the epiphyte load is too great, a loop in the end of the rope and a carabiner
can be used to snug the rope up against the limb creating a top anchor for the rope (see text).
30 SELBYANA [Volume 15(2)
via two parallel locking carabiners, their gates
opposite and opposed as in many mountaineer
ing systems.
The mechanics of the traditional arborist
method of ascent differ from mountaineering/
caving methods. The rope runs from the harness
of the arborist upwards into the tree and over a
limb, then back down and into the arborist's
hands. We refer to this latter half of the rope as
the running line. We use the running line to pull
into the tree, benefitting from the pulley effect
that the limb and line offer (FIGURE 5, Panel 1).
Perry (1978) fixed the running end ofa mountain
climbing rope to a nearby anchor, e.g., a tree bole,
and ascended the fixed line using ascenders. If
the epiphyte load is great, the recreational ar
borist technique discussed below is preferred over
either the traditional arborist technique, or the
Perry (1978) method.
If desired, the traditional arborist method can
be used for re-ascending trees with heavy epi
phyte burdens by securing a true, mechanical
pulley (as used by rescue workers) with a sling
around the branch. Ascent is very smooth and
easy. This might be desirable where several trees
are re-sampled frequently as it reduces body fa
tigue.
Arborist Knot
With sufficient strength and boldness, an ar
borist can hoist into the tree with hands alone.
But because of the mechanical advantage offered
by the line passing over a smooth limb, the weight
lifted is only half body weight (ignoring friction,
of course). Instead of bare hands, arborists em
FIGURE 7. The mechanics of double ascender (A, and ploy the arborist knot (also known as a taut-line
A2) attachment to a harness are similar to those of hitch; FIGURE 4, right and FIGURE 6) or me
mountaineering. Two slings (H, and H2) are attached chanical ascenders.
to the harness. One sling goes to each ascender. It is
Like mechanical ascenders the arborist knot
very important to get the sling lengths exactly right
engages the rope under tension; when slackened,
(i.e., properly adjust the reach), with one sling (B,)
it slides over the rope. Unlike the prussik knot
allowing complete arm extension upwards (but NO
further). The second, lower ascender sling (B is slight (familiar from mountaineering and caving, e.g.,
2)
ly longer than an arm reach. The short sling-ascender Larson & Larson 1982), which has a bilateral
combination (A, and B,) goes above the long sling symmetry, the arborist knot is tied as a single
ascender combination (A, and B2)' The lower ascender strand using an inverted symmetry. Unlike a sin
has one (or two) foot sling(s), C. We prefer mountain gle prussik knot, a single arborist knot can be
eering etriers over fixed length loops as they prove
used for ascending, descending, and traversing.
useful in other contexts (surmounting giant limbs, for
The arborist knot serves as an ascender but
example). D shows the flip line in place around the
requires no special purchase. It can also supple
bole.
ment the climbing kit for those using ascenders
when a second or third ascender is desirable but
unavailable, as when switching from one ascent
2-2.5 m tail of the rope is used to tie the arborist rope to another. Like all ascenders, reach (dis
knot (FIGURE 4, right). To tie into a harness while tance from the knot/ascender to the harness) is
maintaining a useable tail, we prefer the double of utmost importance. The proper reach requires
figure-8 (FIGURE 4, left). This figure-8 knot forms the knot/ascender to be an arm's length above
a 10-15 cm loop which attaches to the harness the head. If too long, the knot/ascender ends up
1994] DIAL & TOBIN: FOREST CANOPY ACCESS 31
1 .
2.
/
4.
3.
FIGURE 8. To ascend a tree, the climber slides the upper ascender as high as possible on the running line, and
then sits (Panel I). This upper ascender is now supporting the arborist's weight via the sling from ascender to
harness. The lower ascender is un weighted and slid upward until abutting the upper one (Panel 2). This raises
the foot slings. The arborist stands up in the higher foot slings, using both ascenders as handholds (Panel 3). In
standing position, the tension is on the lower ascender, freeing the upper ascender to be slid higher. The upper
ascender is slid higher and the entire procedure repeated until the limb is reached.
32 SELBYANA [Volume 15(2)
Traditional Arborist Technique using
Mechanical Ascenders
Many arborists substitute one or two mechan
ical ascenders, such as Clogs, Kong-Bonattis,
CMI's, or Jumars, for the arborist knot (FIGURE
7). The combination of two ascenders (one with
foot sling) and limb-as-pulley smooths the ascent
remarkably and is easier than using the arborist
knot. Even underfit novices have successfully as
cended using the method that combines tradi
tional single rope equipment (ascenders and foot
slings) with arborist rope technique.
The sequence of ascender movements as
sumed by the arborist, i.e., alternately standing
sitting while the ascenders are alternately slid
upwards, is identical to many mountaineering!
caving techniques: the upper ascender is attached
with a sling to the harness, the lower ascender to
the harness and to a foot sling or slings. The
procedure is shown in FIGURE S. This method
and the attachment of the ascenders to the run
ning line allow for the climber to move up as if
FiGURE 9. The flip line hitch tightens under tension fixed rope ascending but actually self-lifting via
but is adjustable with one hand. The other end of the the limb-as-pulley.
flip line attaches with a snap link on the opposite side
of the harness.
Recreational Arborist Method
When the epiphyte load is such that the limb
out of reach; if too short, the ascent is cramped, as-pulley causes the sliding rope to cut into the
frustrating, and inefficient. organic mat and possibly seize, an alternative
FIGURE 6 details how ascent is accomplished method can be used. T. Ness, a recreational ar
using the arborist technique. While only half the borist, recommends the use of ascenders and fixed
body weight is hoisted, arms may tire and hands rope for climbing trees. Ness anchors the rope
blister (polyester-nylon blended gloves with palms to the access limb and not to a ground level tree
criss-crossed with a rubberized substance help) trunk as is commonly the case in single rope
over the course of a 20-30 m climb. As an ascent technique (Perry 1978).
aid, arborists also use the foot lock, whereby the The technique is to tie the initial throw line
feet and knees are brought up and the rope is (or secondary access line if using monofilament
pinned between the feet. This allows the arborist with a projectile throwing device) to the climb
to stand up on the rope while simultaneously line and hoist the climb line over the access limb.
pulling with the hands and sliding the arborist With both ends of the climb line at ground level,
knot higher. the arborist now ties a double figure-S (FIGURE
A significant disadvantage of using the arborist 4) or bowline knot at one end (see any moun
knot occurs if the rope runs over multiple taineering or caving text, e.g., Larson & Larson
branches: when the first branch is reached the 1982, for instruction to tie the bowline), and then
arborist knot must be untied. This requires that clips a locking carabiner into the loop formed
the climber anchor onto the intervening branch (Ness recommends a 7.5 cm screw link as safer
and dangle (or mount it if possible). Now, the and stronger). This carabiner is then clipped to
rope can be grabbed again above the branch (us the running line, locked, and then the running
ing a saw if needed to reach the rope) and then line is pulled downwards. This pulls the cara
pulled over to the same side as the climber. Using biner upward, snugging the rope like a noose
one ascender and the knot, or two ascenders, can around the access limb.
simplify the situation: if climbing with one as The rope is now fixed to the initial access limb.
cender, the knot can be tied on the rope, the It has been fixed from ground level and will be
ascender removed and reclipped above the limb, available for re-use within the tree. The rope is
the knot untied and the ascent continued. With ascended using standard caving or climbing as
two ascenders the knot can be tied to serve as cent techniques (e.g., Larson & Larson 1982).
back-up, and the lead ascender passed over the To re-use a rope within the tree, the arborist
limb and followed by the other. ascends the rope to a suitable limb where the
1994] DIAL & TOBIN: FOREST CANOPY ACCESS 33
rope is unweighted. Then the carabiner is un when placing the flip line around a branch not
locked, unclipped, and the noose around the tree to irritate noxious creatures (T. Laman pers.
limb is released. Like the traditional arborist comm.).
technique, a climber can be dangling beneath the For hanging and observing over long periods
initial access limb with full weight on the rope of time, a more comfortable seat may be desir
supported by that limb, then pull up the opposite able. Bosuns chairs (Munn 1991) and mountain
and free end of the rope and use it over the next eer's portaledges (Nadkarni 1988a) have been
access branch. By transferring weight onto the borrowed from other applications and success
second branch and its ascent rope, the first ascent fully used, whereas hunter's tree seats and in
rope is un weighted and the carabiner-noose as sulated hammocks (New Tribe 1993) have been
sembly can be unclipped when within reach. designed for tree use.
Use of the Flip Line and Moving Higher and Moving About
Utility Harness
Both methods of arborist ascent described
Limbs serve as convenient stances from which above, the traditional, sliding-rope and the rec
to work, e.g., setting traps, marking individuals, reational, top-fixed rope methods, make the rope
collecting samples, etc. To enhance stability, es immediately available for use elsewhere in the
pecially with variable to high winds in many can tree. Because it is not fixed to the ground, the
opies, a second rope over a second limb estab rope can be hauled up and used to move to ad
lishes an adjustable triangulation anchor. Also, jacent limbs, higher limbs, or even adjacent trees.
slings looped in a girth hitch around limbs and Many arborists take two or three 50 m ropes into
attached to the harness serve as back-up anchors. the tree. Still, it is possible to continue to the tree
We found that use of the arborist utility har top (or as near as the arborist dares) using only
nesses offered the most safety, stability, and com a single line by swinging leads (that is alternately
fort while climbing and working in the canopy. using one end, then the other) as one moves up
Rock climbing harnesses, designed for holding ward. When making a transfer, arborists remain
leader falls while mountain climbing, can be tied to the first ascent end while they take the
come uncomfortable while dangling for long pe opposite end and use it or a second rope to set
riods. Arborist utility harnesses have wide, pad up the next ascent. The flip line or a sling also
ded leg loops and waist straps; they are very provides for a second tie-in point and safety re
comfortable for hanging from trees. They also dundancy.
make tree work safer by providing for stable an If the access limb is above or adjacent to an
chors when used in conjunction with the flip line. other limb, stopping and standing at the lower
The main drawback to the professional arbor limb is very convenient. The arborist uses this
ist's utility harness is the weight and cost. These lower limb as a platform to reach the next access
harnesses with heavy straps, large buckles, and limb (FIGURE 5, Panel 2). Ifno limb exists below
leather padding are both heavy and bulky. An or adjacent to the initial access limb, there may
equally comfortable arborist harness at less than be some difficulty pulling into the crotch. The
one-third the weight (approximately 1 kg) and situation is remarkably like being below an over
half the price is available from recreational ar hang during a rock climb. Etriers, extra carabi
borist equipment manufacturer, New Tribe ners, extra slings, and a fifi hook-all equipment
(Grants Pass, Oregon; see Appendix). The rec borrowed from rock climbing's direct aid tech
reational arborist harness offers the light weight niques-allow the equivalent of direct aid for
of climbing harnesses and the functionality of working up the overhang. If the limb is insur
the utility harness. mountable, the arborist can throw for another,
The tie-in anchor point on an arborist harness higher limb from this dangling position.
slides 30 cm side to side, allowing freedom to Whether dangling immediately under the ini
twist, turn, and bend without changing the an tial access limb, or standing comfortably on an
chor torque. Two large D-rings on the harness adjacent limb, the principles of moving higher
sides (FIGURE 3) allow attachment of a flip line by using a new access limb are the same. Widely
as an anchor (FIGURE 7). The flip line is tied to spaced branches may require re-use of the throw
one D-ring with a simple self-tightening, adjust bag to reach the next limb. Otherwise, a neatly
able hitch (FIGURE 9). The line passes around the weighted climb line end will suffice.
bole and clips to the other D-ring. We found the A suitable method weights the end with a dou
4 m model most suitable. A flip line serves the ble figure-8 knot tied 2-2.5 m from the end and
same purpose as a rock climber's daisy chain or neatly wrapped by the tail. The weighted end and
cow's tail attached to an anchor, but is more a few coils of rope are then thrown over the next,
convenient and functional. Care must be taken higher and new access limb (FIGURE 5, Panel 3).