As we enter the season for ‘Fungus Forays’ – or guided mushroom walks, I have decided to delve deeper into the alternative universe of mycology. I want to shed some light on various new and exciting revelations on the sheer magnitude of subterranean fungal diversity, and the fundamental role this has as the courier distribution network operating throughout all healthy-functioning ecosystems.

Inter-fungal functions

Many of us are vaguely aware of terms such as mycorrhiza, mycelium, the notional ‘wood wide web’, and the fact that these colourful, typically domed structures are only the sporadically revealed ‘fruiting’ (spore-bearing) bodies of an even stranger organism. It is neither plant nor animal (although closer in fact to the latter), and spends

most of its life in a very different state beneath our feet. We are also told of some fungi in this state forming partnerships with plants at their root-soil interface, to trade photosynthesised carbohydrates for basic soil nutrients that the plants would otherwise struggle to absorb. Wild orchid species are among the better-known practitioners of this.

But what is becoming increasingly clear is that all plants; from sapling to veteran trees, wildflowers, grasses and rushes, even mosses – depend to a greater or lesser degree on this type of mutualistic mycorrhizal relationship. A lichen, after all, is only one step beyond this, whereby a fungus fully hosts an algal species representing a single organism. 

The mycelial state of a vast number of fungal species is involved, and what is more, they themselves can also combine physically to configure, fine-tune and enhance these functions. It would moreover appear that this inter-fungal activity is facilitated by a communication system detectable as bioelectrical stimuli akin to nerve impulses. It has even been suggested that the rhythmic patterns in evidence here are somewhat similar to vocalised linguistic structures...!

Recyclers

Fungi are quite simply the ultimate recycling agents. They specialise in breaking down complex organic matter and returning the constituent elements to the soil and related growing media, where these are then rendered available to successor generations of plants, then herbivores, and in turn their predators. And all this on a vast, essential and omnipresent scale. 

This role at the nerve-centre of the carbon cycle means that at any one time, the world’s fungi could be driving the sequestration (storage) of an estimated third of annual global fossil fuel emissions. It is therefore no wonder that mycologists are vigorously campaigning for better recognition of fungi in international biodiversity protection strategy, as they are critical to climate change mitigation.

Taxonomic puzzlers

The cryptic lifestyles of fungi have always made mycological taxonomy particularly difficult. But new techniques involving gene-sequencing to compare species’ DNA can serve to not only reveal the true diversity of ‘species’ that could be present in various habitats, but also their ecological roles and the possible evolutionary relationships between them. I place ‘species’ here in quotes because this work is increasingly challenging our basic concept of what a species physically represents, given the potential complexity of their interspecific intimacy on a cellular level. 

Species formerly thought of as a single entity are in fact shown to form clades of several near but separate relations, while others that were believed to be close prove to be nothing of the sort, or conversely are only slight variants of the same species. This clearly requires a fair amount of systematic re-classifying and re-naming of species, all adding to the confusion.

Surrey’s bounty

It only remains to be said that parts of Surrey are among the best-recorded for fungi in Great Britain, and indeed therefore, globally. The reasons are mainly historic, with the proximity of both the Royal Botanic Gardens at Kew and the London Natural History Museum playing a key role. Sites such as Box Hill and Norbury Park, Windsor Great Park and the Esher Commons are national treasures mycologically, with the last of these having the longest national list of recorded species.

 A good many rare species are seemingly unique to Surrey, but this is becoming ever more likely by perception only, due to the exceptional infrequency of their erupting fruiting-bodies.

Mike Waite - Director of Research and Monitoring