Another awesome article by Jules Bristow; this one was originally published in The Bushcraft Journal in 2016.
While there is much debate over the precise meaning of the term bushcraft and its overlap with the term survival, to my mind bushcraft is the set of skills necessary to live comfortably and enjoyably in the wild for protracted periods of time. A deepening understanding of nature is both necessary to practice these skills and, at least for me, a reason to practice them, and we are privileged as humans to be the only creature capable of imagining the world from another organism’s perspective in order to develop this understanding. We can learn, for example, that certain fungi have a need for the nutrients in decaying wood and a preference for certain wood species even if we ourselves do not share these needs and preferences! Although the sense we rely on most is sight we can learn that scent is the primary sense for foxes hunting in darkness, that roe deer mark out their territory by rubbing scent from modified tear ducts onto trees, that barn owls use their acute hearing to zero in on the rustlings of their prey or that wood-ants follow scent trails laid down by scouts.
As well as experiencing the world through senses vastly more acute than ours, other living things may experience our world on a different timescale to us. An oak tree or yew may live for a thousand years, the turning of the seasons a mere breath to them, while a worker bee may live only thirty days in the sunshine in an unrelenting explosion of industry. An ecosystem is made up of a web of interactions between living things, many of which we can observe at our own timescales – we can hear the dawn chorus (so much less harmonious when you learn that the birds are basically saying “Come and have a go if you think yer hard enough!”), watch the glow-worm’s glimmering mating display, observe a buzzard swoop on a vole. There are many others however that take place at a scale or on a timescale quite different to our own.
Plants are far more aware of their surroundings than is commonly supposed. They can certainly detect light, tree saplings growing out of the shadows to form the perfectly tesselating mesh of tree canopies that produces such pleasant dappled woddland sunshine, but because this response to light is so much slower than our own we tend to forget that they can in effect “see”. And most of us are familiar with the response of the Venus fly trap or the mimosa or sensitive plant to touch, but may not realise that all plants respond to contact or pressure. Lone trees or those at the edge of woodlands for example will grow to minimise the amount of their foliage catching the prevailing winds , which would put stress on their boughs.
Less well known is the tentative suggestion that plants may be able to “hear”. We have known for a long time that the constant flow of water up from plant roots produces vibrations, a hum which we can actually tune into to eavesdrop on how much water the plant is transporting. But there are tantalising hints that plants themselves may be able to do the same. Chilli seedlings germinate faster in the presence of a competitor, in order to get a “head start” at obtaining resources like sunlight and nutrients. Astonishingly, in experiments where all possible chemical communication was blocked, chilli seedling still generated faster in the presence of a competing fennel plant than they did alone, suggesting that they were detecting the competitor by some as-yet unknown mechanism, hypothesised to be sound. And plants are known to produce natural insect deterrents in response to being fed on by caterpillars, but it seems that they can also be induced to do so by a recording of caterpillars chewing on leaves suggesting that they can detect the sound of caterpillars feeding.
But perhaps most important of the plant senses is the ability to taste or smell, that is to detect molecules in the environment that convey information. The English oak tree, for example, is home to several hundred insect species, some of which feed upon its leaves. In order to reduce the damage they cause it has a vast array of chemical defences, molecules that may taste unpleasant to these herbivores or even harm them. These chemicals take a lot of of resources to produce however, so the oak will only arm itself when it senses it is under attack. Remarkably it can do this by detecting chemicals from the insects’ saliva as they attack its leaves, tasting them as they taste it. The tree can even distinguish between species and select the best weapon from its arsenal accordingly. And as well as detecting scents or tastes the tree can also produce them, emitting volatile compounds in response to caterpillar attack which diffuse through the canopy and instantly warn other leaves to mobilise their defences. They can even recruit allies – these volatile compounds can also attract parasitic wasps which prey on the caterpillars feeding on them.
But plants’ abilities to communicate go even further with the assistance of symbiotic fungi. The mushrooms and toadstools we are familiar with are merely the reproductive structure of a much larger subterranean organism, a delicate tracery of microscopic filaments called mycelium which liberates and absorbs nutrients from the soil.
TheAlphaWolf [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)]
When these filaments twine around the most delicate of plant roots, making the recycled nutrients available to them and absorbing some from them in return, they are called Mycorrhizae. Ninety five percent of land plants studied to date have been found to be associated with mycorrhizal network, which span entire woodlands interconnecting multiple individual plants and fungi, and it is quite possible the in the species which haven’t we simply do not yet have the technology to detect their fungal partners.
This symbiosis was originally thought to be a relatively simple relationship between two organisms, a plant and a fungus, but it has recently been found to be far more complex than that. The same fungus can link numerous plants of the same or different species, and most remarkably has been found to pass chemicals between them. These may be nutrients, like sugars or nitrates – both mature birch and Douglas fir have been found to give young saplings a helping hand by feeding them extra nutrition through their shared fungal network. It may also be information – plants that have fallen victim to insect damage been found to warn their neighbours to strengthen their defences by means of pheromones exchanged via the same networks.
Such findings challenge our conventional conceptions of “survival of the fittest” as a competition between individuals -perhaps our understanding itself needs to evolve, to consider the fitness of the ecosystem itself. Certainly it changes our understanding of the winter wood, which may seem so still and silent – beneath the soil is a “wood wide web” in constant conversation, the meaning of which we are only beginning to decipher. It would certainly be arrogant to assume we have done more than scratch the surface of the true complexity of woodland ecosystems. We are only just beginning to understand the deep connections between plants and fungi, but already we know enough to be awed by them.
The universe is full of magical things patiently waiting for our wits to grow sharper – Eden Philpott
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