I’m sorry, this isn’t really a post about unnatural bird sex, it’s about mycology in general and truffles in particular. But, there is a non-nativist ecological link, and the bird sex provides a pertinent example. I return to this a bit later on.
A few weeks ago, I was lucky enough to attend a worldclass lecture on mycology right here in Braidwood as part of the inaugural “Truffle Time in the ‘Wood” festival. The presenters were Professor James Trappe, Dr Andrew Claridge and Todd Elliott. What follows is principally my recollection of the information presented by these three engaging speakers. The festival as a whole involved too many folks to mention individually in this post, but see below for a summary of participants and contributors.*
I’m not a mycologist, but I’d always thought I had a workable understanding of the ecology of fungi, they’re the decomposers of our ecosystems, right? They breakdown dead bodies and wastes and release various nutrients back into ecological circulation. Apart from the odd fruiting body, they’re hard to spot, mostly underground; very much out of sight and out of mind.
I now realise, I didn’t know what I didn’t know about fungi, and there’s a lot going on that’s worth considering.
The ecology of truffles, for instance, is fascinating. For one thing, there are a lot more truffle species than the highly prized Perigord which is native to parts of Europe; Australia is covered in truffles of its own. It’s estimated there are nearly 2000 Australian native truffle species, more than in any other continent, and all are thought to be endemic.
Like in other parts of the world, these truffles form symbiotic associations with a variety of plant species. Each type of truffle is limited to one or just a few specific host species or genera. They actually invade the cells of the plant’s feeder roots whilst also spreading through the nearby soil. Because fungal mycelium is much finer than a feeder root, the fungi can access and efficiently absorb moisture and soil nutrients that the feeder roots could never reach. Some of these nutrients are provided to the plant and, in return, the fungi receives carbohydrates which the plant produces by photosynthesis. As such, some fungi are doing more than decomposing detritus on the forest floor. They also directly feed essential nutrients to the primary producers within their various ecosystems, greatly enhancing the productivity of the whole. Plants growing without their fungal companions (like those in soils where fungicides have been applied) are often sickly and lackluster.
As with all other truffles, the Australian ones evolved from those less discrete forms of fungi that raise their fruiting body (the mushroom) to stand above the soil before they open and distribute spores from the gills on the underside of the cap. As Professor Trappe pointed out, the atmosphere above ground can often turn pretty harsh for a soft-skinned fleshy fruiting body, and mushrooms are sometimes desiccated or frozen before they mature. So, because they represent a considerable energy and material investment by the fungal mycelium, above-ground fruiting bodies can be a risky strategy for spreading spores. Probably because of this, some of these organisms evolved underground fruiting bodies (truffles) instead. Prof. Trappe showed slides of a series of different species which represented intermediate stages of this evolutionary process. These included underground fruiting bodies that still contained a vestigial ‘stem’ within the tissue of the truffle; evidence of an above ground fruiting ancestor.
However, if the point of developing a fruiting body is to widely distribute fungal spores (and it is), then growing them in a small underground lump might seem a bit counter-productive. Stuck under ground, those spores are no good for anything, least of all for the survival of the species. How can they spread from down there?
Well, this is where truffle ecology becomes really interesting. As the spores within these fruiting bodies near maturity, the truffle begins to emit an odour that alerts nearby animals to their presence. Knowing that the smell comes from an appealing underground food-item, certain animals (like the bettongs in the image below) will proceed to dig down to the truffle. The truffle is eaten and the spores it contains are spread in the droppings of the animal as it moves around its habitat (also the truffle’s habitat) . Some truffles contain a concentrated layer of spores which are powdery and lightweight so that, as they’re dug up and punctured, they explode in clouds, like a puffball mushroom. A proportion of these spores then settle nearby whilst some are spread further by wind and others are ingested by the animal and deposited later on.
Dr Claridge explained there are different levels of animal interaction with truffles; some animals are ‘obligate’ truffle eaters (eating nothing else), some are ‘preferential’ consumers (preferring truffles amongst a range of other possible foods) and some are ‘opportunistic’ (they’ll eat truffles if they find them, but won’t seek them out). Interestingly, the plant-animal-truffle associations outlined here happen everywhere that truffles occur. Professor Trappe explained this in relation to a Shakespearean drama. He said, ‘wherever you go in the world, you can attend a different theatre and see a different group of actors, but the play is the same’. The same ecological interactions occur despite the fact that different species are present. Therefore this “play” of biological landscape function is on show all over the world, wherever we find plants, fungi and hungry animals.
Since I know many Australian natives, especially Eucalypts, are growing in other countries, I asked Professor Trappe whether Australian native truffles were also present in these situations. He informed me that they were and, in fact, his first encounter with Australian truffles happened to be in California under some of the Eucalypts growing there. I found this interesting as it implies several other things about the ecological interactions in these situations. I didn’t get a chance to ask Professor Trappe directly, but I’d be interested to know what animals are utilising and spreading the Australian truffles in California, presumably they’re Californian natives species or, at least, not from Australia.
Such interactions also prompt me to wonder what other ecological associations are occurring in these situations. Clearly non-native forests are not all barren eco-deserts, as is often assumed and implied by nativist invasion biology literature. Just as with riparian willow forests here in our local region, a large number of species utilise non-native forests for their survival. The arrival of new species is not always a destructive occurrence simply because of their association with European human occupation. The addition of new species within degraded or dysfunctional systems can provide new niches, increase complexity and add to the diversity of ecological interactions, improving overall ecological function and resilience.
As an example, consider the grazing landscapes surrounding Braidwood (especially on the ‘Braidwood granites’ soil type); only 5% of pre-European vegetation persists in this area, and yet, (thankfully) it is not entirely devoid of floral diversity, even if much of what remains consists of non-native species. Birds, reptiles and small mammals find food and shelter among hedgerows and paddock stands of hawthorn, blackberry, briar rose and scotch broom, among others. Braidwood’s urban swamp wallabies utilise the density of these plants along with riparian willows, poplars and elms to shelter during the day. They travel through our area almost exclusively via the riparian vegetation corridors that these species provide. Without these exotic plants we would live in a far poorer ecological landscape.
There are many forms of interaction occurring, often unnoticed, within our local environment. I promised you unnatural bird sex and here I deliver, or rather, the final speaker at ‘Truffle Time in the ‘Wood’ delivered. Todd Elliott provided a fascinating overview of fungal ecology and ecological interaction from his global-scale explorations in mycology. He began by outlining a scientific article that he and Peter Marshal are presently developing in which they discuss an unusual native-nonnative interaction from right here in our own local area.
Bowerbirds (Ptilonorhynchus violaceus) are known for the male’s habit of collecting objects which he uses to decorate a ‘bower’ to attract females. The females select a male to mate with (finally! Bird sex!) based on his ability to collect a suitable display of objects. Any small object may be chosen, so long as its the right colour. Preferred colours vary depending on the particular species. For the satin bowerbird, the preferred colours are blue or mauve.
In Australia today, satin bowerbirds are known for their habit of collecting blue objects cast-off or lost by humans, especially small plastic things like those visible in the image above. Where once these birds would have used natural objects like flowers and berries, today they are more likely to collect bottle caps, pen lids, and pegs from nearby human habitation. I have wondered in the past how the presence of non-degradable plastic might affect satin bowerbirds over the long term. It seems that maintaining an attractive bower is a much easier task now that perishable flowers and berries don’t have to be constantly replaced. Might it change the bowerbird gene pool in some way if successful males no longer spend as much time on this activity? Could a less able object-forager or younger male simply occupy the bower of a deceased successful male and reap the reproductive benefits for years to come?
These potential ecological impacts of plastic sound ‘shock-horror-unnatural’ enough, but what Todd Elliott and Peter Marshall are interested in might be even worse from some perspectives. They’ve noted the native satin bowerbird utilising the non-native blewit mushroom, which has a distinct bluish colouring, to decorate its bower. They theorise that in doing so the birds are spreading this species around our local district. Presumably, the male birds have discovered that the colour of the blewit successfully attracts choosy females. Hence, this pretty non-native is invasively promoting depraved, exotic and unnatural bird sex among innocent native species.
I won’t give away the other details of the impending paper, but Todd Elliott is interested in further research concerning bird-fungi (ornithological-mycological) interactions and asked that audience members (especially bird watchers) contact him with any of their own observations. The species of fungi is always of particular interest, so try to accurately identify it or collect a sample if possible.
For me, this example of non-native invaders promoting ‘shock-horror’ unnatural bird sex provides a clear illustration of the complexity of ecological interactions that can occur within a given ecosystem. Whether it is Australian native truffles feeding small Californian mammals, riparian willows sheltering swamp wallabies, or blue fungus helping the next generation of bowerbirds to be born. No matter where a species is from ‘originally’, it is inherently capable of forming supportive ecological relations with others in its new environment. Not all introductions are an ecological disaster, especially within ecologically impoverished agricultural landscapes like those of our local area.
Despite this, it is often assumed that being non-native automatically implies a negative impact on native ecologies. Without the observations made by Todd and Peter the world would never have realised that blewits are supporting satin bowerbird reproduction in southeast Australia. Although blewits might never replace the blue plastic rubbish currently popular with bowerbirds, at least they provide a biodegradable alternative in some areas. How many other supportive ecological associations between pre-European species and more recent arrivals are currently ignored or obscured under existing environmental regulations and destructive nativist initiatives?
Whatever your views on these broader ecological questions, the Truffle Time in the Wood festival was a great pleasure and success. I know from conferring with other attendees that the lectures provided by our three inspiring speakers were thoroughly enjoyed. Much thanks to Todd Elliott, Dr Andrew Claridge and Professor James Trappe for sharing so much of their experience and knowledge, there was far more on offer than I could possibly recount here. Fungi in general, and truffles in particular, are a fascinating topic. Given their supportive interactions with various plants and animals, and their vital role in soil health and function, a working knowledge of these organisms and their diversity provides an essential component of any ecologically-informed perspective.
*Truffle Time in the ‘Wood contibutors/particpants included all of the people and businesses associated with the Braidwood’s Farmer’s Market. Major sponsors were Terra Preta Truffles and the Bungendore and Braidwood Community branch of the Bendigo Bank. Braidwood Central School provided the venue for this great community event. Visiting executive chef Christian Hauberg delighted attendees with Truffle and Chestnut soup, Truffled scrambled eggs, Steak rosini rolls with truffles and Sweet truffle Portugese tarts. All proceeds from these food sales were donated to the Braidwood Hospital.