Gold is the colour of Autumn. Watery sunlight filtered through honey. A return of shimmering birdsong in brave defiance of the cold. Ephemeral leaves nearing the climax of their final act. Yet beholden of this scene we fail to see something so fundamental to life that to most it is akin to alchemy. Once the tree has broken down and stored the life-giving chlorophyll from its leaves and the autumn gusts have broken the final tenuous link, the leaf flutters gently to the ground. Not landing upon the leaves from last year and those of the year before in ever increasing layers similar to the tree’s own annular rings. In fact those previous leaves appear nowhere to be seen.
Without decomposition we would be swimming in piles of leaves miles deep. So, what is responsible? The process is complex and can involve many different organisms, however key to all decomposition, and life as we know it, are fungi. Not plant or animal but in a kingdom of their own, fungi are often misunderstood. Salient to us mainly in terms of their fruiting bodies i.e. mushrooms and toadstools this belies the true nature of fungi.
The majority of the living organism remains largely unseen in the form of mycelium – a network like structure of individual microscopic threads called hyphae. A teaspoon of soil may contain 10km of hyphae. Mycelium can be thought of as both a decentralised nervous system and body of the fungus. Mycelium has been shown to exhibit intelligence and problem solving abilities. For example, bread mould has been able to solve complex microscopic mazes. Whereas slime moulds have been shown to find the most efficient way through that other notorious type of maze, IKEA.
Fungi are thought to have evolved up to 1 billion years ago, but it’s their part in the colonisation of terrestrial habitats that have arguably had the biggest impact to life on earth. One such turning point was the moment a fungal cell joined an algal cell in the start of a literally ‘ground-breaking’ collaboration. The outcome was lichen; an extremely hardy organism capable of surviving on bare rock and instrumental in the formation of the first inland soils on Earth.
In a lichen the fungal part is able to break down the bare rock to release the nutrients required by the alga. The alga in turn photosynthesizes light to provide energy. Walking around Arnos Vale you will see many different types of lichen starting the process of colonising the headstones. If left the lichen will continue to break down the rock and start to form a small layer of organic matter or soil. Moss will then take hold in small crevices that can hold water. Eventually after many years the soil layer will be enough for higher plants to establish. Then we start to see how, through succession habitats are formed.
Another way that fungi are responsible for life as we know it is through a relationship formed with plants. Mycorrhizal fungi with their microscopic hyphae can penetrate much deeper into soils than the larger plant roots. Thus making nutrients available with greater efficiency. Sharing these nutrients with plants in exchange for energy is the basis for this relationship, much like in lichen. However, mycorrhizal fungi are more interesting as they form networks that link different plants, often of differing species.
This relationship has been studied most in woodland where it is possible that the entire habitat is linked by mycorrhizal networks in what has been termed the Wood Wide Web. Much like our internet, plants are able to use the mycelial network to communicate with other plants, warning of pests so others can prepare. They are also used to foster the next generation of plants for instance, tree saplings in heavy woodland shade can survive by being fed nutrients through the mycorrhizal network. In this way they are ready for when a gap in the canopy appears and they can quickly grow to fill it.
Fungi have also played an important role in the development of the human species. It is thought that fungi, in particular yeast, are responsible for the birth of civilisation. A bold claim yet hunter gathers’ nomadic lifestyle had to become more settled to be able to grow grain in order to brew beer and bake leavened bread. Our relationship with fungi, however, goes back much further and more intimately. Yeast as well as several other similar fungal species are present in our gut as part of our microbiome. These fungi along with numerous types of bacteria play an important role in digestion. Although not well studied are likely to have profound implications for our health. Not only this but certain species live exclusively on different parts of our bodies, we are literally covered in fungi.
As I have briefly tried to show fungi are profoundly entwined with life on earth. The more we look the more connections we see. Healthy ecosystems have complex fungal networks connecting them, making them more resilient and unlocking the nutrients required to sustain them. Humans are only just starting to realise the importance of fungi and so the questions arise: Are fungi the dominant lifeform on Earth? Do forests exist to provide energy to fungi or vice versa? Do we cultivate yeast to provide beer or do yeast cultivate us to provide food? Who is really in control? Gaia (see previous blog) is more complex than we can ever comprehend. Our lives and future as a species depend on fungi. It’s time we gave them the attention they deserve.
Blog written by Liam Matthews, Arnos Vale Estate Supervisor
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