Trees: A Trove To Be Treasured
Let’s begin with a cautionary tale: there once was a wondrous tree bordering my road. Every day as I drove along, I could see this vision in front of me, the tree’s canopy over-arching the entire thoroughfare, a green source of shade, a haven for wildlife and a lofty reminder of the island’s jungly past. One day it was suddenly no more, chain-sawed down by the owner of the roadside plot. When I asked him why, he told me it took up too much space.
In Phuket, space is money and trees are a blot on the landscape. That towering tree, a dipterocarp, had probably been there for a hundred years, spared by the makers of the road decades ago, but now reduced to a lifeless stump. The butcher might have got a few dollars for the oily wood
Trees are not only one of the wonders of our world, they are indispensable to our survival on the planet. They are extraordinarily precious, and extraordinarily vulnerable. Despite the thousands of seeds each adult tree produces, only one offspring will make it to maturity. Yet we cut them down with impunity,
The epithet ‘vulnerable’ is not a misnomer; trees possess almost human-like patterns of behavior. Indeed, recent research has derived a new term ‘wood wide web’, a reference to their ability to behave in a neighborly way by sharing nutrients and water with fellow plants in the vicinity. They do this by harboring good fungi in their root systems which assist in the assimilation of moisture and minerals from the soil.
Another protective function is performed by so-called ‘mother’ trees. As mature specimens in a forest or copse, they are able to use their extensive root systems to protect the less robust roots of younger trees in the immediate vicinity. Instead of a policy of each for herself, the parent tree actually helps others .
In this way, as in many other regards, trees are crucial to the survival of the planet. In my view, it is no exaggeration to say that they are globally more important than any other vegetative life form. And they protect not only their green cousins, but, unwittingly, the whole human race.
Consider this: during photosynthesis, a process that trees need for survival, they use energy from the sun to collect glucose and to sequester in their tissues potentially harmful carbon dioxide. Not only carbon, but other air pollutants such as particulates. Even better, this process produces oxygen , the life-enhancing gas all of us need to survive. Without oxygen in our atmosphere, we would all be dead in minutes. More trees means less CO2, more O2. It has been estimated that a 100 foot tree, one smaller than the one hacked down by my neighbor, produces 260 pounds of oxygen per year. An acre of leafy trees can replenish the oxygen consumed by eight people. When the poet William Wordsworth spoke, more than 200 years ago, of ‘one impulse from a vernal wood’ affecting human behavior in a positive way, he spoke truer than he knew.
Nowadays, we know a lot more about ‘vernal woods’. One of the reasons why the world is experiencing so many floods and landslides is because the forests are no longer there, both to act both as gigantic sponges, or as protection against what is known technically as ‘fluvial erosion’. Floods are both the deadliest and commonest form of natural disaster. What tree root systems do is to help mitigate the impact of sudden precipitation; they absorb and tenaciously hold excess rainwater, and only gradually release it into the atmosphere via their leaves ..
Foliage is also capable of retaining moisture in its leaf spaces or stomata and allowing it to disperse slowly in an evaporative process. That mist that enshrouds the canopies of our tropical jungles is a product of this arboreal respiration.
Add to that the capacity of root systems to bind the soil and help prevent erosion. Tiny, almost microscopic hairs interact with the surrounding soil and help to stabilize it. When this root density is high and healthy, there is almost no soil loss, even in super-wet conditions. No trees, no root hairs, no protection.
When the coastlines of South East Asia were devastated by the tsunami of all tsunamis in 2004, it was the casuarina trees that mitigated some of its most disastrous effects. Here in Phuket, a three-deep line of these beach-side conifers met the full fury of the advancing wall of water and saved the local community from a watery grave. A few trees keeled over, but their extensive root systems enabled the majority to survive and protect.
Trees are, of course a feature of most kinds of landscapes, even desert regions. That they can cope with a degree of aridity is in part the consequence of their capacity to transport and pass on moisture. For instance, a tree in a coastal region probably has access to lots of rain water. Twenty kilometers inland, the climate may be much dryer. So the coastal tree will transmit moisture via its roots to an adjacent tree and thence to others in a sort of underground relay, a life-enhancing process akin to osmosis. Recent research has shown that trees can also pass on messages to other trees when under threat from leaf-eating animals, enabling them to produce bitter tannins in the shoots and foliage which deter browsing animals such as deer or giraffes. Isn’t that amazing?
The role of dead trees, less spectacular, is still beneficial. When venerable specimens finally fall to the forest floor, they offer nutrients and shelter for approximately 1/5th of all the planet’s creatures, thereby performing a key function in the ecosystem by providing a haven for thousands of interacting plants, animals, insects and especially fungi. Fungi break down dead wood [lignin] and cellulose by releasing enzymes. The resulting material decomposes and eventually becomes part of the nutritive layer of humus, a layer crucial for the development of a new generation of plants and trees.
Sadly, all too many trees have been falling to the floor before reaching maturity, let alone old age—fighting a losing battle against homo sapiens. And not just in the Amazonian, African or Indonesian rain-forests of today. While it is romantic nonsense to say that a red squirrel could formerly travel from England’s south coast to Scotland without touching the ground, it is clear that in mediaeval times, much of the landscape was wooded, a haven for deer, wolves and boar.
By the industrial revolution, these ancient, broad-leaved forests, dominated by slow-growing oaks that require three hundred years to mature, had disappeared: victims first of the insatiable demand for wood for fuel, ships and half-timbered buildings, subsequently for charcoal for the smelting industry. Nowadays, little prehistoric forest remains: the United Kingdom has the lowest concentration of woodland in the whole of Europe. An unenviable statistic
But it was the twentieth century that became most notorious; the century when so many trees died before their time that there was no chance of a recovery. Yes, land clearance accelerated and trees everywhere succumbed to the chain-saw and bush fire. But some losses could not have been foreseen. Two key deciduous species, the elm and the ash, are in terminal decline. An indelible feature of my rural childhood, sombre monsters taller than the church belfry, I climbed the wayside elms every day. Not without hazard – the boughs were notoriously brittle. Once upon a time, elms were everywhere. Look at a John Constable painting of the Suffolk countryside—say ‘The Haywain’—and you will surely spot ulmus procera somewhere in the picture.
Not any more. The elm skyline and even the elm hedgerow has virtually disappeared. Why? Because of the depredations of a small beetle, ophistoma ulmus. It drills holes in the rough,, tough bark of the trunk, and thereby allows entry to two varieties of fungus which feed on the zylem tissue within. The tree responds by plugging the life-lines of this porous layer, thus preventing water and nutrients from traveling through the tree. In essence, the victim commits suicide. It starves to death
The ash [fraxinus excelcior] has also been affected by modern disease. Again a fungal destroyer, it apparently began in the 1990s—and spread…. The figures are catastrophic: 99% of 90 million trees are likely to die. The United States has its own problem—emerald ash borer attacks perpetrated by a bright green beetle. Larvae feed on the living tissue within and interfere with the trees ability to convey nutrients and water. An infestation can topple a tree in two short years.
Both these pandemics are the consequence of neglect and mismanagement of our natural resources. Both began in far-flung corners of the globe: the ash borer is native to Asia, Dutch elm disease originated in Poland. Both infestations went unchecked for years. If the actions of the chain-saw on the rain-forest have been all too calculated and visible, these two malevolent beetles worked their depredations unseen. Man’s neglect and transport systems have done the rest.
Trees could be forgiven for thinking; it never rains but it pours. They have been having a rough time of it. True, there have been welcome and worldwide initiatives to re-plant, restore and preserve. In Thailand, the country I call home, there are actions, many at local level, to plant mangroves, the most ecologically important tree in the tropics. Brazil, which has lost 17% of Amazonian rain-forest in the last half century, now has a six year re-planting program. While Thailand’s primal forest is now measured at 37% of the land mass, rubber trees have replaced 60% of that lost jungle.
Malaysia can tell a similar tale about oil palms. Generally regarded as the most profitable of all tree crops, the palm has colonized a massive six million Malaysian hectares, a four fold increase in a decade. Further afield, in North America, the primary conifer forests of cedar, spruce, Douglas fir and hemlock have mostly gone, but there are strictly enforced rules about replacing lost trees. Canada leads the global way, with governmental plans to plant two billion trees in the next decade.
Not all news is good news and not every country is as ecological aware as Canada. For the most part, it is still a tale of diminishing habitats and encroaching urbanscapes. When I built my house in Phuket nearly twenty years ago, I had uncluttered views of seas and mountains in all directions. Slowly, inexorably these vistas have vanished, blotted out by apartment blocks and condos. In the process, many trees have inevitably bitten the dust.
Replacing them is only part of the solution. New seeds, let alone seedlings, take ages to grow to maturity, and often they struggle to germinate and grow vigorously on land deprived by the slashing and scouring process of most of its top-soil. Moreover these new plantations are normally composed of one species, mono-cultures driven by commercial considerations that fail to take account of bio-diversity. When I walk through a plantation of havea braziliensis, I am shocked by the cathedral-like silence. No bird song, no rustlings in a non-existent undergrowth. As Shakespeare put it more than four hundred years ago: ‘Bare ruined quires where once the sweet birds sang’. Always better alive than dead, trees are an ecological miracle. One mature oak [quercus] can not only remove, annually, ten pounds of harmful pollutants such as particulates from our atmosphere, it is a miniature city, home to creatures, ranging from mammals, reptiles and birds to beetles, butterflies and fungi. Cavity nesting birds, up to five hundred species of butterflies, creatures such as deer and squirrels dependent on winter supplies of acorns, leaf- eating jays and woodpeckers and caterpillars—the list goes on and on.
We murder trees at our cost.