Arbuscular mycorrhiza (Image by By Oyarte-Galvez (AMOLF) – https://www.eurekalert.org/multimedia/986302, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=135745890)
Dear Readers, it’s long been known that arbuscular mycorrhizal fungi form ‘trading relationships’ with up to 70 percent of all plant species, swapping phosphorus and nitrogen in exchange for carbon-based sugars, Not only do these fungal networks sequester carbon, but they are also an important part of the structure of soils, helping them to retain water and nutrients, even after the fungi themselves die.
Scientists have been extracting soil samples for decades, with over 16,000 cores being extracted from 4,000 sites – these have been analysed to measure the density of hyphae (the fungal threads that exchange materials with the plants) and from these the amount of mycorrhiza at each location can be extrapolated.
From this information, the scientists have produced this extraordinary map. Do have a look – you can zoom in on a particular location to see how it’s doing for fungal density.
https://a-hidden-infrastructure.spun.earth/map#2.6/28.85/59.93
One of the things that the map tells us is that over 40 percent of the biomass of these arbuscular mycorrhizal fungi is in unimproved grasslands and wetlands, particularly the Tibetan plateau (with 11.4 metres of mycorrhiza to every cubic centimetre – just imagine how densely packed the fungal threads must be!), the Sudd wetlands in South Sudan, and Flint Prairie in the US. However, the density on croplands is 47 percent lower, which is worrying for soil fertility, climate change resilience and biodiversity. The fungicides that are used on many farms kill the mycorrhiza directly, while constant ploughing and turning over the soil damages the networks. Then fertilisers are used to replace the nutrients lost . Hopefully, the revelations from this study might flag up how damaging these practices are.
Looking at the map of the UK, it was interesting to see how the highland peat bogs and grasslands of Scotland were in the top 2 to 3 percent of density for the world as a whole, but as you travelled south it got worse and worse, with some areas in the south of England being in the bottom 45 percent for mycorrhizal density, I had a lot of fun with this – you can zoom in a long way, and I imagine you could probably pick out a local greenspace and see how it did. However, some areas have very little or no data, so we probably shouldn’t extrapolate too far from the general trend.
The scientists are eager not to suggest that this means that plants are talking to one another all over the planet via fungal networks, but there is definitely a degree of interconnectedness that hadn’t been appreciated before, and which has major implications for our ecosystems and for our food production. Do have a little play with the map, and have a look at the ‘story’ attached. This is pioneering work.
The map is here.
The story is here.
I was surprised to see that Olympic Nat’l Park had pretty low numbers, especially since it includes the Hoh Rain Forest. The whole area of the park is greyer than the surrounding area.
Meanwhile, the only areas of Seattle that have data have quite good numbers! I know some of those areas are parks, but they are well-visited, often managed (certainly not undisturbed soil!). There are a couple of samples near my house, one of which is literally on a city highway that is quite built up and is considered in the top 3% globally! There is certainly no park there. So odd.
Interesting, Shannon – I suspect that there will be all sorts of anomalies, especially at the detailed level. Interesting overall though, I think….
Well plants don’t ‘talk’ but connect, link, or otherwise communicate at some level – why not? Fascinating.
What a fascinating map! I’m sure there are anomalies, but I’d like to believe that some sections of our St Ives Bay dunes – which are home to 25% of the plant species found in Cornwall – do indeed have a fungal density which is in the top 1% globally!