Because fungi are found everywhere in the natural environment, they have a major influence in a number of areas. Tonight's talk considers some of those areas.
Ecological studies have found that in healthy forest soils, 90% of the total living organisms consist of fungi. The remaining 10% are made up of organisms such as nematodes, algae, rotifiers, protozoa, springtails, mites and worms.
Therefore this overwhelming mass of fungi obviously play a major role in the stability of natural ecosystems.
In fact they are the major organisms responsible for:
In addition, fungi provide habitats and food for numerous invertebrates. Others, particularly the truffle-like fungi, provide food for native mammals. In fact they form the major part of the diet of the Long-footed Potoroo, the endangered Gilberts Potoroo and some Bandicoots.
In Australia there are over 250,000 species of fungi. The majority are microscopic and invisible to the naked eye, but over 10,000 are the macro or larger fungi. Most known indigenous fungi are endemic, but there are also numerous exotic fungi.
The talk tonight concerns only the macroscopic or larger fungi - that is, those fungi whose reproductive fruiting bodies are easily seen, such as mushrooms, boletes, corals, stinkhoms, truffles, discs, cups, and morels.
Fungi reproduce by microscopic spores, which are manufactured in the fruiting bodies. In the species, Wood Blewit Lepista nuda, they are manufactured in the blade-like gills found underneath the cap. The numerous microscopic spores can sometimes be seen with the naked eye when they fall en masse and form what is called a spore print. This can be seen on the stem or surrounding vegetation, or on paper if you make a spore print. The Wood Blewit has a pink spore print.
The colour of the spore print is particularly useful for aiding in the identification of genera of soft-bodied fungi with a cap and gills.
The colours of spores en masse range from white at one end of the spectrum, like the Toughshank Collybia eucalyptorum to the black of the Lawyers Wig Coprinus Commatus to black, depending on their genera. The Spectacular Rustgill has a rusty-brown spore print.
Other species manufacture spores in the pores underneath the cap such as Boletes or Polypores, like Scarlet Bracket Pycnoporus coccineus or in spore sacs like puffballs - such as Common Prettymouth Calostoma fuscum or like the Anemone Stinkhorn Aseroe, where the spores form in a slimy mass on the disc at the top of the stem near the base of the arms. In general fungal spores are dispersed by wind, but in cases like the stinkhorn, the spore mass stinks like carrion and attracts flies that slurp up the slime and thus disperse the spores.
Hypogean fruit bodies of the truffles-like species have a completely enclosed fruit body and spore mass. In this case mammals such as Potoroos and bandicoots, attracted by the smell, eat the fruit bodies and disperse the spores. The black wrinkled feature in the centre would, in other fungi, form gills.
When a spore disperses, finds a suitable growing medium and conditions are favourable, usually related to moisture and warmth, it sprouts microscopic filaments called hyphae, which elongate and branch frequently at the tips to create a web or mat of strands called mycelium.
Mostly this is not visible, but in the case of the Yellow-tongue Coral CIa varia amoena it is indicated by fruit bodies which form above the radiating mycelium, and form rings.
Fruit bodies of macrofungi in one area may arise from a single extensive mycelium, or from a large number of different individuals.
The common Fairy-ring Champignon Marasmius oreades often forms fairy rings in suburban situations. Sometimes the mycelium becomes twined to form thicker threads called rhizomorphs that can be seen with the naked eye weaving through the forest litter. This is one way to identify the Tall Bonnet Mycena cystidiosa.
Unlike plants, fungi cannot manufacture their own food. They have to obtain it in other ways. Fungi absorb nutrients from the substrate on and in which they grow. It is this factor that makes them so important in ecosystems.
One Group obtains nutrients and energy from the break down of dead and decaying organic matter of both plants and animals. This is mostly dead wood and litter, but also includes animal skin, bones and horn. These fungi are characterised as SAPROTROPHIC fungi.
In the process of obtaining food, fungi break down organic matter. The cellulose and lignin of woody plants is then made available for other organisms in the form of carbon dioxide, nitrates, phosphates and other nutrients. In fact research has shown that annually, fungi are responsible for recycling hundreds of billions of tons of carbon dioxide to the atmosphere.
Fungi are one of the few organisms that are able to break down cellulose and lignin.
The small agaric, Ruby Bonnet Mycena viscidocruenta, is another common saprotroph. It decomposes native litter and may be found in gardens and suburban parks as well as native bushland. Some saprotrophs such as the Small Dung Button Pomnia erici prefer a specific substrate, in this case, dung. These are called coprophilous fungi.
The Ghoul Fungus Hebeloma aminophilum is so named because of its association with decaying animal carcases (when only skin and bone remain). Its growth is stimulated by the nitrogen released as the flesh decays. Fruit bodies can also be stimulated to appear by application of nitrogen rich substances, such as urea. This is probably why fruitbodies can sometimes be seen around the edges of picnic areas in native forests, when there is no apparent carcase.
The problem for fungi that break down plant material is the fact that it is mainly a carbohydrate diet with not much nitrogen available. Most organisms cannot grow and multiply successfully unless they can obtain a continuing source of useable nitrogen for the production of all the nucleic acids, proteins, enzymes and other compounds essential to growth. The carbon: nitrogen ratio should be about 30:1, but the diet is often up to 300:1
It has been shown that among a number of wood decaying fungi, such as the Oyster Mushroom Pleurotus ostreatus, sets out to trap and absorbs nemetodes to add nitrogen to their diet.
The hyphae produce tiny appendages that secrete droplets of a potent toxin. This toxin paralyses nematodes in seconds but does not kill them. The paralysed victims are located by specialised directional hyphae, the cuticle is penetrated and the contents digested. Research, to date, has shown that 5 species of Pleurotus capture and kill nematodes in this way. In addition, this group of fungi is also known to attack and consume bacteria.
Another wood decaying fungi genera, Hohenbuehelia, create sticky knobs on hyphae that specifically target and trap nematodes, which are then consumed.
A second group of fungi obtain their food by PARASITISING other organisms with no benefit to the host, which usually dies. Most are microfungi.
However, amongst the macrofungi, species such as Honey Fungus Armillaria sp. are parasitic on trees. The fungus attacks the living sap wood le outer layer just under bark which leads to the death of the tree. Often fungi are both parasitic and saprotrophic. After it has killed the tree, the fungus then breaks down the dead wood and recycles the nutrients.
Other parasitic fungi, known as vegetable caterpillars, parasitise the larvae of underground moths, such as the Wattle Goat Moth.
The Lacy-stemmed Vegetable Caterpillar is interesting since it is most usually seen parasitising another Vegetable Caterpillar - the Antlered Vegetable Caterpillar Cordyceps robertsii when the antlers appear yellow. However, it has been observed growing from an underground parasitised moth larva.
Cordyceps that have been dug up sometimes show the parasitised caterpillar. The part of the stem that was below ground is short and indicates that the moth must have been growing near the soil surface. Sometimes the caterpillar lies much deeper in the soil and the Cordyceps stem below the ground has been known to grow as long as 40 cm.
It is very obvious that without the major action of fungi aided by bacteria and small invertebrates (such as worms, beetles and flies), the earth would soon become totally littered with dead plants and animals.
A third group of fungi obtain food by forming a SYMBIOTIC RELATIONSHIP with green plants, mainly trees. This is mutually beneficial to both organisms.
One form of symbiosis is known as a MYCORRHIZAL association. Here, the microscopic hyphal threads of the fungus join to the rootlets of trees (usually when the tree is young) to the mutual benefit of both.
Trees rely on mycorrhizal fungi for normal healthy growth - the fungus enhances the ability of the tree to absorb water and supplies almost all the essential minerals. In return the tree provides carbohydrates for the fungi.
This association is widespread amongst green plants and involves hundreds of species of fungi so that each tree is often associated with hundreds of thousands of kilometres of fungal hyphae.
In addition Mycorrhizal fungi provide chemical protection from pathogens and physical protection from root-eating invertebrates such as nematodes by trapping them in webs of mycelium.
Fungi such as the indigenous Vermilion Grisette Amanita xanthocephala are associated with eucalypts in native forests. The Splendid Red Skinhead Dermocybe splendida is another mycorrhizal native species, easily recognised by the paprika red gills and yellow on the stem and yellow mycelium at the base of the stem. It is found in native forests and is also associated with eucalypts. Mycorrhizal relationships may be with only one species of plant, or several, and the plant may associate with just one or many fungi.
The Pine Brittlegill Russula integra, is an exotic species associated with introduced Pines. The mauve-reddish cap, white stem and brilliant yellow spore print are very distinctive characteristics.
A closer symbiotic relationship is that of a fungus and alga when the total integration of the two species form a lichen. The Yellow Navel Omphalina chromacea is thought to be the fruiting body of such a union. It is always associated with a green algal mat.
Thus it can be seen how vital fungi are for retaining a balanced ecosystem - they recycle nutrients and maintain the health of green plants, especially trees.
Therefore conservation has to be an important issue. In this case knowledge is the key. However, fungi, as compared to the flowering plants, have:
Many of the collections in herbaria have only the type collection or not more that one or two collections. The collections tend to be biased towards the species with longer-lived fruit bodies, such as the leathery fungus, Golden Curtain Crust Stereum ostrea, as well as puffballs and polypores, that are more long lasting and easier to preserve than the soft-bodied fungi.
In contrast to the amount of work that has been done on Australian flora, the lack of knowledge of Australian fungi is an enormous disadvantage in the conservation of endangered fungi. This is most worrying considering the vital roll they play in the environment.
It is important to have a list of all fungi in herbaria, but not all are databased on the virtual herbarium (which links all the herbaria in Australia). Data information on host, substrate and habitat preferences are lacking, and thus potential threats cannot be determined.
Hence, it is difficult to include any fungi on the lists of endangered species apart from those established as rare. This lack of listing is also mainly due to scarcity of resources and expertise in Australia. However, there have been some moves to include fungi on state conservation listings
One fungal community is listed as an Endangered Ecological Community in the NSW Threatened Species Conservation Act of 1995. This is for the assemblage of fungi in the Hygrophoraceae family, mostly Waxcaps Hygrocybe, found in Lane Cove Bushland Park near Sydney.
The assemblage consists of more than 20 named and described species. This number of Waxcaps Hygrocybe species is very high compared with other known sites both in Australia and overseas. Six of the species are listed as rare.
The Community is threatened by water-borne pollutants, encroachment by exotic weeds, dumping of rubbish and garden refuse, excess pedestrian traffic in sensitive areas and inappropriate bush regeneration.
Recently in Victoria, Nyora reserve was recommended for listing because of the presence of Hypocreopsis 'nyora'. A recently found species, rare and only found on long undisturbed/unburnt stands of coastal tea-tree. Morchella esculenta, another rare species, was put forward as vulnerable due to indiscriminate collection for gourmet eating.
In WA two species of Amanita, Amanita cameiphylla and A. griseibrunnea are listed as poorly known taxa. Priority 2 (ie known from fewer than 5 sites) in the Priority Flora List of CALM.
Recently the scientific communities of NSW, QLD and Victoria have recommended listing the loss of woody debris as a potentially threatening process under each state's legislation.
The removal of woody debris means:
But the work of mycologists is necessarily slow, and the capriciousness of the appearance of fungi is a big drawback in the search for knowledge.
One way to acquire knowledge quickly and efficiently is to harness the interests of volunteers and non-specialists who can make the great contributions by gathering information on macrofungi.particularly information on distribution, habitat and substrate.
One such project, the Fungimap scheme was set up by Tom May (the senior mycologist at Melbourne herbarium) in conjunction with the FNCV. The central organisation is run from the Royal Botanic Gardens, Melbourne and involves volunteers from all over Australia. They were asked to submit sightings and ecological data for certain species of fungi (100, at the moment). To date over 15,000 records have been received from around Australia.
The herbarium coordinator (aided by a number of volunteers) deals with correspondence and membership and inputs the sight data onto a database to produce maps. All the information can be seen on the web site. In addition, Regional coordinators promote the scheme in their areas around Australia and set up workshops and fungal study groups.
The criteria for the fungi selected was that:
For example Pixies Bonnet Mycena interrupta is easily recognised by the blue, translucent-striate cap, white disc at the base of the stem, and the substrate - fallen eucalypt branches and trunks. Due to the increasing knowledge of distribution of fungi. from the records sent in by the Fungimappers the records show the extended range of the species into South Australia
Similarly the Vermilion Grissette Amanita xanthocephala fungimap records have been updated to show its much wider range. The dates on which the species was recorded have been used to create graphs to show major fruiting times.
This illustrates how much Fungimappers have contributed to base line data of fungi distribution, habitat preferences, substrate, and fruiting times. They are providing an invaluable tool for further research.
For more information about Fungimap call 9252 2374, or email fungimap@rbg.vic.gov.au or go to the website at fungimap.rbg.vic.gov.au
Thankyou, Pat Grey
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