Trained as a zoologist trees have by and large evaded my attention, instead I have always been drawn by the enigmatic animatic thus I have remained blind for many years as to the wonder that trees possess. Initially the trees were frameworks housing the focus of my study, canopy invertebrates, but little by little the trees have become a leading interest. For to spend time within a tree, hanging from its branches, taking shelter under its canopy, examining the body of a tree for historical signs, then a whole life story begins to emerge. I am by no means the first to muse over trees, there is a vast collection of poetry about trees that exist.
‘Trees are poems that the Earth writes from the sky’ – Kahlil Gibran
I have watched observantly and listened intently, gleaming knowledge from arborists, from those who rig trees with ropes and climb as a profession and those who climb trees as if it was as ordinary as riding a bike. Each tree has a story to tell and look carefully enough you can begin to read it from the body language of the tree. I am fortunate to be in one of the oldest rainforests in the world. Throughout the epochs there has been times of climatic instability and change but the rainforests in Borneo persisted. A stable rainforest refuge amidst such change has contributed to the diversity and endemicity of the flora and fauna found here. Threatened by logging, fires and conversion to plantation, the rainforest may have shrunken but still, for now, it continues to persist. Fortunately nearly 25% of Sabah’s rainforest is protected.
According to the woodland trust 76 species of tree, native and non-native, can be found across the UK, this meagre number is nothing compared to the 3000 plus species of tree that have been named in Borneo. Of which almost 270 belong to the family Dipterocarpaceae. The family of giants. In the lowland rainforest of Maliau Basin these giants are some of the tallest in all of the tropics, the tallest reaching 88 metres. Frequently anchored to the ground by huge buttress roots, although not all, the uniform, often perfectly cylindrical trunks, race to the sky seeking light through the canopy. Branches are nowhere to be seen until the top 10 m or so where the body of the tree is capped with only 2 or 3 branches offering tufts of leaves to where the sun can shine. These tall and slender armies of Dipterocarps are in stark contrast to the low branches and spreading, domed canopies of the Beech, Oak or Yew with their twisted and distinct frames. Such high and few branches poses difficulties for climbing trees, those wishing to 1) find a secure anchor point and 2) to get the rope to the anchor point high in the canopy. So how old are such large trees? Without seasonality there is an absence of the growth rings found and used to age trees of temperate forests. Thus the age of these tropical giants for the most remains concealed, revealed only through more sophisticated techniques based on radiocarbon dating. Dipterocarps flower rarely but often coordinate mass flowering on the conclusion of an El Niño period. As this happens to be now we check frequently for flowering with the knowledge that with flowering will come bees. A danger all tree climbers are rightfully anxious of, most carrying their own nightmarish experience of a bee attack.
Putting aside the obstacles of high branches and bees, selecting a tree to climb requires an appreciation of the health of a tree and an ability to determine this by reading the traces left behind from past events. The history of a tree manifests in patterns of growth. Explained with more clarity and knowledge by Claus Mattheck and any professional tree climber, but the basic essence of the nature of tree growth is that it will react to environmental stress. History of environmental stress can be picked up by a well trained eye. A tree will grow to reinforce weak areas: a tree bent by storm damage will counter balance itself by growing more on the opposite side. Weak areas can be identified by unusually abrupt bends in a branch, indicating past breakage and by what technically is called epicormic growth or less technically panic growth. New shoots growing from the collar of a damaged or broken branch, innately weak as such shoots are attached solely to the outer layers of a stem and not stitched into the heart of the tree. Over millions of years, close mutualistic relationships have formed between trees and fungi, allowing both to flourish in nutrient poor rainforest soils. Fungal Mycorrhizal penetrate the hairs of giant root masses nourishing the growth of the tree. These are very different to the fruiting bodies of fungi seen on dead wood, the presence of which along a living trunk may indicate possible internal decay.
A tree can show many signs of ill health, fungal decay, crown die back, cankers, swellings and bulges on one side of a stem, epicormic growth, dead wood in the canopy, yet life seeks a way. Trees are resilient, I have seen trees with cavities in the trunk so large that daylight can be seen through to the opposite side yet new shoots and leaves still emerge from the branches. Or a new stem growing from within a completely hollowed out and decayed trunk. A tree does not give up on life easily. The tallest trees beckon you to climb up above the main forest canopy, yet often a ‘broken top’ deters a climber. As when a tree begins to reach its mature years it will drop branches, self-managing its sheers size and weight so it can remain standing for more years to come.
So should I climb the tree? The visual tree assessment that I have been taught to do governs the final decision but as I rest my hand on the rough bark the most unscientific decision making process begins. A sense of calm envelopes me inviting trust to climb or one of forewarning to be left in peace. Unlike climbing rock, the tree is a living organism, it listens to its environment, it reacts, it responds and it allows you to climb amongst its branches.