Monday 24 August 2020

Fundamental fungi: the forgotten kingdom vital to our future

At the end of 1993 the Convention on Biological Diversity came into force. A key piece of global legislation in the promotion of sustainable development, it marked a change in focus for environmental concerns. Whereas previous high-profile conservation efforts such as those of the World Wide Fund for Nature or Greenpeace were frequently aimed at individual species or regional ecosystems, the legislation initiated by the 1992 Earth Summit in Rio de Janeiro was aimed at the biota of the entire planet. However, there are still segments of enormous ecological importance that are lacking sufficient research.

I've previously discussed how little attention general-readership natural history pays to the kingdom of fungi, which may have somewhere between 1.5 million and 3.8 million species. Of these, less than 150,000 have been scientifically described. Clearly, this is one life form where our knowledge barely covers the tip of the iceberg. It's hardly as if this attitude is a new one, either. While Linnaeus produced comprehensive editions on plant and animal taxonomy in the 1750s, it took over seventy years for anyone to bother with fungi: it wasn't until 1821 that another Swedish naturalist, Elias Magnus Fries, produced an equivalent work called Systema Mycologicum.

Thanks to the majority of fungal material living either underground or in dark, damp environments such as leaf litter, the kingdom fails to get the attention it deserves. Even the forms we see more regularly, such as mushrooms and symbiotic lichen, engender little interest. Many people no doubt still mistake the former as plants - and are scared off any interest in the wild forms due to the dangers of poisonous species - while the latter are rarer in polluted, i.e. urban, environments and fail to compete in sight and scent with the glories of the flowering plants.

In the eight years since I wrote about the lack of interest in fungi, I've found reason to mention the long-forgotten kingdom in various important contexts. For a start, numerous animals and plants are becoming critically endangered due to fungal pathogens accidentally being spread by global travel. In addition, research over the past three years has shown that Aspergillus tubingensis and several other types of fungi show promise as a bio-friendly solution to plastic waste. Finally, last month I looked at non-animal protein substitutes, including the mycoprotein-derived Quorn.

Despite the potential of these various forms of fungi, the organism's losses due to rapid environmental changes don't appear to be garnering much attention. The IUCN Red List, which tabulates the differing levels of threat faced by all life on Earth, only shows 343 fungi as currently endangered; this contrasts with over 43,000 plants and 76,000 animals on the list. Undoubtedly, the Kingdom Fungi is being given an underwhelming amount of attention just as we are discovering how important it is to maintaining ecosystem stability and for the future of our species.

Recently published reports of studies conducted in the Amazon region show that deforestation has a long-term impact on soil biota, which in turn affects the entire local ecology. Studies of a range of habitats, such as primary forest, agricultural land (including monoculture), pasture/grazing, forestry plantations and secondary/regenerated forest showed that although overall fungal mass might remain consistent, species diversity is far lower outside of the original rainforest. The lack of fungal variety was linked directly to the lack of plant diversity in those biomes, with recovery a slow or unlikely prospect due to the newly-fragmented nature of the landscape preventing efficient dispersal of fungal spores.

There are some obvious points that agribusiness seems to ignore, such as the effects of pesticides and fertilisers on local fungi and the loss of microhabitats vital to maintaining a healthy variety of fungal species. If only more generalist fungi can survive the change in land use from the wonderful diversity of the rainforest (with up to 400 fungal species per teaspoonful) then this may have repercussions for future farming. As an example, the fungus Fusarium oxysporum has a phytopathogenic effect on agricultural plants including palm oil, but without competition from a wider cross-section of fungi (for example, Paraconiothyrium variabile) it could spread rapidly within a dismal monoculture environment. 

As a predominantly visual species, we humans are unthinkingly biased about the natural world based upon what we see: think cute giant panda versus the unappealing aesthetics of the blobfish. It really is a case of out of sight, out of mind, but unfortunately no amount of spin doctoring will make fungi as much loved as furry mammals. Yet our attitudes need to change if we are to maintain the delicate ecological balance; fungi are highly important for recycling nutrients, regulating carbon dioxide levels, and as a source of food and pharmaceuticals. Yet they remain the soil equivalents of the ubiquitous underwater copepods, unsung heroes of the global ecosystem. It's about time we took a lot more notice of this forgotten kingdom.

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