March 4, 2013

Kingdoms in the Canopy (III): Climbing Trees

By now you may have noticed I have a growing obsession with my summer study subjects, epiphytic bromeliads. Those hanging zoological gardens that adorn the trunks and branches of neotropical trees (Figure 1).
Figure 1 - Flowering bromeliads

I've already mentioned how I collect them – by climbing trees and cutting the bromeliads down. What I haven't really explained it how I climb trees.

Last March, I completed the Basic Canopy Access Proficiency course, offered by Canopy Access Limited. The course teaches you to use double rope canopy access techniques to pull yourself up into the trees, as well as tying knots, differentiating between good and bad trees to climb, and everything to do with staying safe whilst suspended in mid-air from ropes over a branch.

First things first, choosing your tree. This is important, not only must it suit the purposes behind your climb (in my case: are there bromeliads?), there needs to be a suitable anchor branch to hold your weight, anything you may be carrying, and very heavy rope. While no tree in a natural environment will ever be completely flawless, it's important to watch out for external roots, broken branches, cankers, insect nests, cavities, or any other signs that the integrity of the tree may have been significantly reduced. There also needs to be an appropriate anchor tree nearby, that you'll attach your ropes to.

Figure 2 - Throwline

Once you've chosen a suitable tree and checked the bottom of it for snakes or any other lurking hazards, you need to rig it. As aforementioned, the rope is very heavy, and you're trying to get it up God-knows-how-many metres into a tree. So, before you can get the semi-static rope you'll be climbing on up, a thin – but very strong – throwline has to go up (Figure 2). A classic way of getting the throwline up is by tying a weighted sac to the end of it and shooting it from an oversized slingshot. And I really mean oversized, take a look at (Figure 3). This is harder than it sounds, I swear.

After what can amount to many frustrating shots and much profusive swearing, the throwline is up over your fancied branch and the weighted sac is on the ground on the other side of the tree. This is the side you tie both ends of your heavy rope to, by holding them together and using hitch and half-hitch knots. Back to the other side of the throwline to pull the rope through.

Figure 3 - Bigshot
The side you detach the throwline from is the side you'll climb. Back to where your rope is coming from. The idea behind this method of climbing is that you can always (and should ALWAYS) be attached to two lines. Both lines are actually the same rope (hence tying both ends together). The middle and most of your rope remains in its bag, thus avoiding getting entangled with the vegetation of the forest floor. The rope then has to be attached to your chosen anchor tree. Two slings around the anchor tree's trunk enable GriGris (Figure 4) to be attached. Each line has to be fed through a GriGri and locked off. A third sling provides an extra attachment point for the lines to be tied into. This set-up is called a Ground Based Rescue System (GBRS, © Canopy Access Limited).

So, although things would have to go truly horribly wrong for your GriGris to fail, there would be the additional safety given by the rope lock around the GriGris. In the devastating scenario that that failed as well, your lines would be attached to the third sling via alpine butterfly knots fed into a karabiner. If that part were to fail too, you shouldn't be qualified to climb and deserve to fall out of a tree for attempting to.

Figure 4 - Canopy Access' Ground-Based Rescue System (GBRS).

Anyway, the whole point of the GBRS is that it's a sturdy, backed-up set-up, PLUS it can safely be loosened from the ground if the climber needs rescuing. This is a crucial aspect of tree-climbing, because no matter how thorough your preliminary assessment of a tree is, there can always be surprises lurking in the canopy, especially in an environment like a rainforest. While the BCAP course covers aerial rescues (i.e. climber rescuing climber), it is much slower than and less efficient than simply being able to lower the casualty from the ground. Plus, it means your (essential) ground crew need not know how to climb, just operate the GBRS properly.

Since your GBRS has so many layers of safety, undoing the butterflies holding your lines to the third sling and the knots around the GriGris shouldn't pose any great danger while lowering the climber – gently unlocking the GriGris and slowly letting the rope through them will normally do the trick (leaving it at normally because I won't go into potential nightmare scenarios here!).

Enough about rescuing. The climbing is the part I like. When I have my full set of gear on, I feel nearly twice as heavy. Granted, this is somewhat exaggerated and I am a small person, but still! Lotta gear – below a picture (Figure 5).

Figure 5 - Personal kit

Contrary to what you might think, it is not your arms that work most once you actually start climbing, but your legs – or your leg, usually. During ascent, you're attached to the rope via the chest ascender on your climbing line and your shunt on the safety line. A hand ascender clips onto your main line, as far up as you can reach, and from this dangles your footloop. You climb by dragging the hand ascender above your head and pulling down on the footloop, back straight so there's enough weight pulling the rope through the chest ascender. Some people use two footloops so all the stress isn't on one leg – personally, I have thus far only used my right leg.

Figure 6 - Me climbing a tree.
Descending is an easy matter – except I tend to forget which way up my I.D. or descender goes. This is why one must always have two points of attachment at least: If I were to feed the rope into my descender the wrong way round, and then locked off my chest ascender (necessary in order to descend), I should be caught by my shunt on the safety line. Not an ideal situation, and I sincerely hope this never happens to me, but comforting none the less. Unless you've forgotten to drag your shunt up with you so that it is never below hip height; in which case, if you fall, the shunt will still catch you but the impact of the fall between you and the line attaching you to the shunt is likely to break your spine.

Anyway, that's the basics of double rope canopy access, as an answer to those who have asked me how I climb trees.

Figure 7 - Me about 20 m up a tree, hovering over a bromeliad. This tree is particularly nice to climb for the lack of epiphytic and neighbouring vegetation after about 5 m. The bottom is riddled in chaotic vegetation and there is a bullet ant nest somewhere around its roots, but still! A nice climb and near to camp.

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