Fascinating fungi questions and answers

On behalf of the Rewilding Community of Practice, we are excited to report on the ‘Fascinating Fungi – Invisible Allies in Rewilding event‘. It was an excellent opportunity to learn about the latest findings and developments in the fields of mycology and rewilding, both from science and practice. Our speakers presented nuanced views on the role of rewilding for fungi and vice versa.

We were thrilled to see this was an interesting topic for you and we thank you for attending and actively engaging with the speakers at the event.

After the speakers’ presentations, we held a Q&A session, at which you had many interesting questions directed at the speakers.

We didn’t find the time to answer all of them live, so the Rewilding Community of Practice reached out to the speakers* to have them answer your questions for you. If you missed the event, make sure to watch the recording.

speakers at the Fascinating Fungi Event

All you wanted to know about fungi and rewilding

David Satori

The Wood Wide Web, an idea that’s been around for almost as long as I have, has caught the imaginations of many mushroom enthusiasts, especially now that mycology is having a moment out in the public square. The WWW sparks debate amongst seasoned mycologists, who argue of its inaccuracy and misconception. So let’s take the time to explore my views on this, shall we?

For our intents and purposes, the World Wide Web is more or less a decentralised network distributed across space in which nodes on that network (people) can connect with almost every other node and exchange information.

Let’s contrast that to a woodland, and for now let’s stick to the case of ectomycorrhizal (ECM) fungi – those that form characteristic mushrooms in the autumn like this Orange Oak Bolete. A single tree can host several dozen species of ECM fungi, and within each species there may be multiple genetic individuals so that the tree may effectively be harbouring hundreds of individual fungi. Some of those ECM fungi will be associating only with that tree, and some will be associating with multiple trees, but all of them will be transferring nutrients from the soil into the tree based on source-sink gradients.

These fungi can detect self from non-self, and they’re not able to fuse together to form a large continuous mat of mycelium in which nutrients flow freely. They’re individualised, and in fact, can sometimes display competitive behaviour when it comes to root tip colonisation. So the Wood Wide Web is really a collective of countless individuals, and is very different from the free flowing structure of the internet.

So what do I think of the wood wide web? I think it’s a useful heuristic that people can intuitively grasp to speed up their understanding on the topic, even if that doesn’t take them to a complete understanding. What other three-word analogies can you think of that are as swift at bringing people to 50% of an understanding of the topic? You’ll be hard pressed to find anything that comes close to that, and I trust that anyone who is committed to learning more about fungi will eventually develop a more accurate and nuanced view.

Michael J. Hathaway

I guess the first thing to say is that such debates are part and parcel of healthy scientific discourse. In my anthropological training, I don’t think that any statement is proven, rather they can be more or less resistant to challenges from others. Some statements have survived massive challenges, and other statements are pulled down and quickly discarded. I am grateful for Simmard’s work in getting us to ask new sets of questions that sometimes push back on certain deep assumptions about how the world works.

One of the really interesting aspects to these debates is the question of scale, what is the scale of the scientific claim? Is someone saying that these forms of sharing are happening between a few trees of a few species in the Pacific Northwest? Are they saying this is a general principle of all forest interactions? Or is this a general principle of ecological relations writ large? For at least a century, there has been a common assumption from the Anglo-American tradition that life is fundamentally competitive, and so it isn’t surprising that some of Simmard’s claims might elicit a strong response. When there were claims that trees might preferentially provide resources to their kin, this seemed to better fit a model of competitive struggles for resources, but it is also interesting to figure out how this might happen (i.e. if trees are growing by seeds, how is it that they recognize their own kin and might preferentially supply nutrients to them?). Scientists who work deeply with symbiotic relations have been learning more and more about the complexity of such relations that don’t always neatly fit into existing categories such as parasitic or beneficial relations, especially as such relations may change depending on the context and so forth. I’m agnostic about the specific claims to what Simmard or others put forth on the wood wide web, especially recognizing that the knowledge on this topic is rapidly changing, and would encourage further research.

Bethan Manley

The Wood Wide Web concept has really done wonders for the field of mycorrhizal research. I wouldn’t imagine that we would have such an exploration of mycorrhizal networks in bestselling novels, TV, and countless documentaries without it. 

There is a general consensus in the scientific community that it’s highly likely shared fungal networks do exist. However, we just don’t have a lot of scientific evidence on what they do, and there hasn’t yet been direct evidence of them moving resources between different individual trees or plants. We do have a responsibility as scientists to be transparent about situations where a popular concept or idea has little scientific backing. The trouble is that the way a lot of the media I mentioned has portrayed this concept is that it is a concrete fact in science that trees share resources, yet there is almost a complete lack of science to back this up. 

Equally, from the perspective of fungal biologists, the WWW concept is a tree-centric way of seeing an ecosystem. It doesn’t give fungi any agency or pay attention to the fact that fungi are complex organisms with their own evolutionary history. So we also need to put as much energy into understanding what the fungi are doing, and what they want, as what the trees are doing.

There’s so much to learn about shared mycorrhizal networks and how they operate in relation to their plant hosts, and this is a really exciting question to shed more light on.

Michael J. Hathaway

At the global level, there are lots of creative experiments happening. In terms of their distribution throughout the world, there are certain hot spots. There is a long history of medicinal use of fungi, especially in Asia, but we could argue that (apart from fungally created penicillin) that the West has systematically underexplored and underfunded medical possibilities.  

Michael J. Hathaway

That’s an interesting question, and likely true. I would assume that it would really be a place-specific question and another big question is how do we want to value rewilding, do we want to create our own hierarchy in a given place, or would be want to say any species is equal with each other? I was intrigued by David’s comment that in the UK some are working towards the “biodiversity net gain,” and I was wondering if people are thinking about the relative value of various species presence, or is each species counted as equal? Going for equality starts to get really tricky really fast when one starts to include microbes.

Michael J. Hathaway

Likely a kind of assessment about microbial health would vary dramatically between different ecosystems. Perhaps there will be studies to look at what are assumed to be model “healthy ecosystems” and then do microbial studies, but it might be hard to make generalizations over too much distance. In general, the question of “health” is really tricky but for sure important. In humans, it is sometimes looked at as ‘the absence of disease,’ but we know that this is a very limited understanding, and I would assume that many ecosystems that many experts would describe as healthy also have lots of lots of existing diseases, which is actually part of the diversity itself.

Bethan Manley

Totally agreed with Michael, what is a ‘healthy’ microbial community will differ hugely between ecosystems. Part of what we want to establish at SPUN is which mycorrhizal fungi make up a healthy ecosystem in different biomes of the world, as a baseline for restoration of degraded ecosystems. This is a really tricky thing to establish, but the more data we gather, hopefully the more we can understand which species are our key players across different regions and biomes.

David Satori

The best way of introducing native fungi for the purposes of restoration is to co-introduce them with their plant hosts, as they’re unable to survive in the absence of a symbiotic partnership. However, if we’re considering drought conditions, previous research has found that low rainfall actually hindered both plant and fungal colonisation capacity, and once the ground was sufficiently hydrated, there was no need to inoculate with mycorrhizal fungi as they managed to naturally disperse into those environments themselves. On smaller scales (e.g., gardens or small farms), there’s a case to be made that mulching with myceliated wood chip or straw can be both beneficial in terms of moisture retention, but also nutrient enhancement for plants growing in their vicinity.

Questions you asked Bethan Manley​

“There is a general consensus in the scientific community that it’s highly likely shared fungal networks do exist. However, we just don’t have a lot of scientific evidence on what they do[…]”

Bethan Manley

We have a thriving research community of SPUN Science Associates that is growing every day, and these are really the crucial component of how we increase our data on mycorrhizal community composition throughout the world, so we always encourage anyone who studies soil, fungi, or mycorrhizae to get involved. Aside from scientists, we are incredibly keen on getting more people involved in some form of practical citizen science approach. Join the SPUN newsletter and watch this space! In the meantime, we always encourage people to get involved in their local mycological societies and to see what’s going on in their local areas for fungal rewilding – we want people to form their own mycological networks!

We do – and as I’m sure you can imagine, it looks very different to the EMF map. It’s remarkable to be able to visualise the differences in the predictions for these distinct mycorrhizal types. However, the AMF map is based on ITS amplicon sequencing data, which many people will know does not capture AMF diversity particularly well, though it’s great for EMF. Because of this, the AMF map is not based on as much data as we’d like, and we’re working to change this. We have started using AMF-specific primers as well as general fungal ITS primers for all of our samples, and hopefully soon this will give us much more in-depth knowledge on AMF species and their distributions across the globe.

We are interested in total diversity, but we will always include new sequences in our assessments, too, this is very interesting to us. The trouble with this work is the question – what is an AMF species? These fungi have hundreds of nuclei per cell, many of which have different DNA sequences, and there are different isolates that can look like different species. Without morphological data through culturing, which is very very difficult for these obligate symbionts, we can’t register new AMF species, but we certainly can assess which different sequences are out there.

I have no idea sadly! Something I’d love to look into.