Pyronema omphalodes. Photo: David Catcheside.

This winter, Pam and David Catcheside continued their surveys of the fungi on Kangaroo Island after the catastrophic fires of 2019 and 2020. Reports on previous findings were published in these blogs:

• Fire blog 4: Fungi and fire
• Preliminary studies of the fungi in Flinders Chase National Parks after the 2020 fires

After a brief, preliminary survey in April, we considered that July would be optimum for the main survey, which would include Dr Teresa Lebel, Senior Botanist at the State Herbarium of South Australia, Helen Vonow, Curations Manager, and Julia Haska, an Herbarium Research Associate. However, a COVID lockdown aborted that trip: Julia was already on the island, but just as Teresa and Helen arrived at Cape Jervis, well ahead of time for the noon ferry, they learned a lockdown would start at 6pm. Pam and David were en route at Lucky Bay so as a small compensation we all met up at Deep Creek Conservation Park to look at fungi there, before heading home in time for the curfew. The variety and abundance of fungi at Deep Creek made it even more galling that we were not able to explore the fungal offerings of Kangaroo Island, though we did make some interesting collections.

Although Teresa, Helen and Julia were unable to join us, we were able to schedule a week-long KI trip in late August. However, as the fungal fruiting season in South Australia is usually from June to early August, we knew we had missed the optimum time. An additional constraint was that some sites we usually survey were off limits due to feral pig control operations.

We recorded 35 species of fungi, making collections of 27 of these. One third (10 species) were fire-associated, pyrophilous species and included disc, stonemaker, as well as wood-rotting fungi.

Disc fungi

Disc fungi are amongst the early colonisers, forming mats over the soil surface, helping to bind soil particles and reduce erosion. We found a few patches of the orange Pyronema omphalodes (above) and scattered groups of Pulvinula, whose bright orange discs with their paler, smooth and hairless undersides stand out against the burnt soil.

Pam never trusts the outward appearance of the majority of disc fungi, recognising that the microscopic characters of ascospore size and number, ascus size and shape and features of other cell structures are necessary to determine species. Indeed, each of the four collections of Pulvinula that were made differed in some of these characters, suggesting they belong to different species, two of them possibly undescribed. Planned molecular work will clarify this.

Pulvinula tetraspora (left) and its 4-spored asci (right). Photos: David & Pam Catcheside.

Other pyrophilous disc fungi such as species of orange Anthracobia and black-brown Plicaria and Peziza, found after the 2007 fires and in 2021, were absent. It is possible that these had fruited early this year in June or July but it appears probable there is a lower abundance and fewer species of pyrophilous discs than after the 2007 fires.

Pulvinula sp. (left) with 8-spored asci (right). Photo: David & Pam Catcheside

Mycorrhizal fungi

Scleroderma albidum, an earthball. Photo: David Catcheside.

Mycorrhizal fungi are essential in all forest ecosystems, providing minerals and water to their partner tree. Laccaria species, common colonisers of land cleared by fire or other disturbance, were present, but few other mycorrhizal fungi were found — just a few specimens of Amanita and Cortinarius and an earthball, Scleroderma albidum (right).

Mycorrhizal fungi are expected to be affected when their symbiotic plant partners are killed by fire (Dove & Hart 2017) so it is not surprising that they will be depleted following fire. Again, it is possible that they fruited earlier but it is of concern that we found so few of these important fungi.

Wood-rotting fungi

Fungi are responsible for much of the breakdown and recycling of organic matter, releasing nutrients and making them available for new plant growth (Ingold & Hudson 1993; Crowther et al. 2012). After the summer fires of 2019-2020 there was plentiful substrate:  large quantities of fallen bark, dead branches, logs and trunks were at all sites. Rainfall on Kangaroo Island in 2021 had been high and we had expected to find fluffy mycelium and patches of flat ‘paint’ fungi on some of the wood. However, in spite of our careful examination, even the lowest and dampest layers of the piles of fallen bark showed little evidence of the usual ‘rotters’. We surmised that the fungal inoculum was insufficient to start breakdown of the bark.

]We did find a few wood-rotting bracket fungi. One of the most common was Porodisculus pendulus, which grew in extensive swarms up the burnt trunks of eucalypts. This is a small hoof-shaped pored bracket and the specimens were much tinier, less than half the size, than those we had found after the 2007 fires. We also noted the lilac bracket, Rhodofomitopsis lilacinogilva, and shelf fungus, Stereum hirsutum, but these are not considered to be obligate fire-associated wood rotters.

Wood rotting fungi: Porodisculus pendulus on burnt eucalypt trunks (top), Rhodofomitopsis lilacinogilva (middle), and Stereum hirsutum (bottom). Photos: David Catcheside.

Dung fungi

On a brighter note! One little fungus that was in abundance was Poronia erici. It was growing mostly on kangaroo dung but it also grows on the dung of other marsupials. It forms hard white button-like discs punctuated with tiny black pores which communicate with minute ascus-containing flasks embedded in the disc. Spores are released through the narrow necks of these flasks. The presence of this fungus is a positive sign that marsupials are returning to the burnt sites on Kangaroo Island and possibly reintroducing fungi lost to the fire.

Poronia erici. Photo: David Catcheside.

Monitoring of fungal succession after fire and re-establishment of pre-fire fungal assemblages may inform better management of the environment after fire. It was unfortunate that COVID-19 prevented us from a proper assessment this year.

Further reading

1. Atlas of Living Australia. Pulvinula Boud.
2. Catcheside, P. (2009). Phoenicoid discomycetes in Kangaroo Island. Fungimap Newsletter 38: 5-8.
3. Crowther, T., Boddy, L. & Hefin Jones, T. (2012). Functional and ecological consequences of saprotrophic fungus–grazer interactions. ISME Journal 6: 1992–2001.
4. Dove, N.C. & Hart, S.C. (2017). Fire reduces fungal species richness and in situ mycorrhizal colonization: a metaanalysis. Fire Ecology 13(2):37–65.
5. George, P. (2008). Fungimap survey on Kangaroo Island. Fungimap Newsletter 36: 13-15.
6. Grgurinovic, C.A. (1997). Larger Fungi of South Australia. (The Botanic Gardens of Adelaide and State Herbarium and The Flora and Fauna of South Australia Handbooks Committee: Adelaide).
7. Ingold, C.T. & Hudson, H.J. (1993). Ecology of saprotrophic fungi. In: The Biology of Fungi, pp. 145-157. (Springer: Dordrecht).
8. McMullan-Fisher, S.J.M., May, T., Robinson, R., Bell, T., Lebel, T., Catcheside, P. & York, A. (2011). Fungi and fire in Australian ecosystems: a review of current knowledge, management implications and future directions. Australian Journal of Botany 59: 70-90.

Contributed by Pam Catcheside (State Herbarium Hon. Associate)
& David Catcheside (Flinders University).

The native plants from Kangaroo Island’s Flinders Chase continue to recover from the intense and devastating bushfires of 2019/2020. In the last week of February 2021, a team from the State Herbarium of South Australia – Helen Vonow, Tracey Spokes and Andrew Thornhill – went to Kangaroo Island to conduct a week-long botanical survey of the national park areas where bushfires had occurred. The purpose of the trip was to assess and collect plants that had grown back one year on. The team collected 350 plant specimens over the western, northern and central parts of Kangaroo Island at 13 different sites. They also visited another 12 sites and made observations of which species of plants were growing back. More than 60 species could be identified in the field; these species appear to be recovering as expected, given that the Australian flora is tough and has evolved and adapted to fire over a long time. Other species recovery will need to be observed over the coming months and years. This field work, along with upcoming trips in May, contribute to tracking the recovery of the KI wild vegetation and assist in supporting the recovery of rare and threatened species, with a number of other projects underway seeking to protect the unique and diverse flora of the island.

Tracey & Helen examining plant regrowth in the field. Photo: A. Thornhill.

Continue reading →

Sugar gum woodland in Wanilla Conservation Park, regenerating by epicormic regrowth, c. 3 years after the Wangary fire. Photo: Peter Lang.

In January 2005, the Wangary wild fire swept rapidly across southern Eyre Peninsula under conditions not dissimilar to those of the recent Kangaroo Island and Mount Lofty Ranges fires, and with reports of particularly intense and hot burns.

The Wangary fire burnt vegetation quadrats at nine different sites, which had been surveyed only the previous year as part of the Biological Survey of South Australia program. This provided an ideal opportunity to investigate post-fire recovery and changes to plant and animal species composition. The quadrats were re-surveyed using the same methods in 2007, three growing seasons after the fire. Findings were published by State Herbarium botanist Peter Lang and (the then) manager Peter Canty, together with Robert Brandle, in the following report:

P.J. Lang, P.D. Canty & R. Brandle, Biological impacts of the 2005 wildfire on southern Eyre Peninsula: monitoring post-fire recovery within three years using Biological Survey of South Australia sites. (12.7mb PDF)

Less than three years on, the vascular plant species richness had increased substantially from pre-fire levels in nearly all sites, with species losses outweighed by gains. The total species count for all sites rose by 43 (from 150) for indigenous species and by 19 for alien species (from 25). However, an index based on cover scores, showed a large disparity in responses of alien and indigenous species, with a post-fire jump of 136% for alien species compared to only 11% for indigenous species.

The report also documents and illustrates the regeneration modes observed — re-sprouting, seedlings or both (something that we plan to pursue in a future blog). Some sugar gums, for example, retained their major branches intact and had been able to regenerate quickly by epicormic growth. Some were killed in their upper parts and were re-sprouting basally, whilst others were completely destroyed and had to rely on seedling recruitment to regenerate.

Sugar gum open woodland with dense and diverse understorey, well recovered 15 years after Wangary fire, Wanilla Land Settlement Conservation Park. Photo: P. Lang.

Sugar gum (Eucalyptus cladocalyx) is a very distinctive eucalypt that is endemic to South Australia, with three isolated populations on Eyre Peninsula, Kangaroo Island and in the southern Flinders Ranges, now treated as different subspecies (see also the Flora of South Australia chapter on eucalypts; 33.8mb PDF). Recent DNA sequencing (both nuclear and chloroplast genes/markers) confirms that it has no close relatives. It is also ecologically significant, as a dominant tree for distinctive plant communities with varied and, often, species rich understories.

Concerns were raised about the impact of the Wangary fire on sugar gum plant communities, and these may be highly relevant for the recent Kangaroo Island fires, which also burnt large areas of sugar gum woodland. It seems that on certain soil types and where the fire was particularly intense, mass regeneration from seed occurred and that the highly successful adaptive response of this eucalypt may cause problems.

The following comments were made on page 39 of the report:

Sugar Gum forms a unique community both structurally and floristically that is of high conservation importance. It is valuable as plant and animal habitat, due in part to its structural characteristics in readily producing hollows, abundant fallen timber and, beneath its umbrella-like canopies, much open space which provides for a variety of diverse understorey types.

Depending on the severity and frequency, fire can have deleterious impacts by consuming a substantial amount of fallen timber and destroying hollows. In addition, where major seedling recruitment of Sugar Gum occurs, the structure of the resulting community will be changed substantially due to crowding and consequent overshadowing and nutrient/water competition. This effect has been observed for Sugar Gum regeneration in the Flinders Ranges over a 20 year period of following a severe wildfire in Mount Remarkable National Park. This fire led to the development of many dense stands of thin-stemmed trees, understorey suppression and a much reduced capacity for hollow formation. In both the Tucknott Scrub sites (KOP00501 and KOP00601), there was a dense and extensive establishment of seedlings from 10 cm to 2 m tall […]. Without intervention, it is expected that over the ensuing decades these will produce a similar crowded overstorey structure as observed at Mt Remarkable; indeed it is highly unlikely that natural thinning could produce a typical Sugar Gum community structure with well-spaced large trees in the lifetime of these stands. Failure to restore this structure will affect recovery of dependent wildlife species.

Mass recruitment of sugar gum seedlings (orange-coppery coloured foliage in mid-distance) amongst sparse existing trees, Tucknott Scrub Conservation Park, c. 3 years after the Wangary fire. (Foreground seedlings are golden wattle). Photo: P. Lang.

Recent observations on southern Eyre Peninsula, now 15 years on from the Wangary fire, show that those predictions are proving correct. In some places, particularly lowland areas with sandier soils and heathy vegetation, sugar gum plant communities have regenerated well and still retain their diverse open structure (see first two of above images). Elsewhere, however, in hilly areas such as in Charlton Gully, and the disturbed woodlands of Tucknott Scrub Conservation Park, the previous woodland structure with large well-spaced trees supporting diverse and species-rich understories has been lost. Instead there are now masses of closely crowded young erect trees resembling woodlots with understorey plants mostly eliminated by overshadowing and competition for nutrients and water.

Dense sugar gum regeneration near Tucknotts Scrub Conservation Park, 15 years after Wangary fire. Photo: K. Pobke.

Dense regeneration of golden wattle (Acacia pycnantha) has a similar effect, but only for a limited period due to its relatively short life span. It is a very different scenario though for sugar gums which can persist for centuries. While some natural thinning of sugar gum may still occur as the trees continue to age, we should not expect that they will return to the original structure as they reach maturity: it is well known in forestry practice that initial spacing affects resultant tree habit and size. As well as supressing understorey, the greater density of smaller and less spreading mature trees is likely to result in reduced and delayed hollow production, which is another concern since the availability of hollows can be a limiting factor for many wildlife species.

Observations of older post-fire sugar gum regeneration in Mount Remarkable National Park, and some massed post-grazing recruitment of red gum in the Mount Lofty Ranges, support the Eyre Peninsula observations that natural thinning is not going to return these formations to a more open woodland structure within the time frame of human life-spans at least, and probably much longer. This raises the issue of how the original open vegetation structure arose and was maintained, and whether active management involving selective thinning is now warranted as a conservation measure.

Dense sugar gum regenerated from seed 15 years after Wangary fires, showing deep leaf litter and lack of understorey, Tucknott Scrub Conservation Park. Photo: K. Pobke.

Prepared by State Herbarium botanist Peter Lang

(acknowledging helpful discussions with DEW ecologists Jason Van Weenen and Kat Pobke).

Eucalyptus leptophylla, regenerating by regrowth from lignotuber, after fire in Billiatt Conservation Park, Murray Mallee. 18 June 2014. Photo: P.J. Lang.

The eucalypts are the epitome of resilience in surviving and regenerating after a bushfire. What first appears to be blackened and destroyed forests of tree trunks, returns as thousands of new shoots all over tree trunks and branches. It is almost without a doubt that the eucalypts have come to dominate Australia with the help of fire, given their ability to quickly recover from it. What do the eucalypts do that many of the other plants don’t, and what can we expect to see happen to eucalypts in the South Australian areas that have been burnt?

First of all, there is more than one way that eucalypts recover from fire. Some species recover by sprouting new leafy shoots all over their trunks and branches. This is called epicormic regrowth and is possible because many eucalypt species have buds buried deep below their bark that are protected from fire. It is triggered by the plant being under stress. Quickly regrowing leaves all over the burnt structure means that it is essentially functioning as a tree again and this is a massive advantage over other plants that have to regenerate from seed, to become a sapling, and then a tree, a process that can take years.

Eucalyptus cladocalyx, regeneration by epicormic regrowth, nearly 3 years after fire in Wanilla Conservation Park, Eyre Peninsula. 24 Sep 2007. Photo: P.J. Lang.

Other eucalypt species grow from lignotubers. A lignotuber is woody swelling at the base of a tree trunk. This structure can often be buried deep within the soil, another way of protecting a plant from fire. While the plant above the ground will be destroyed by a fire, the underground material remains untouched. New shoots appear from the lignotuber and the plant begins growing again from the ground up.

A third way that eucalypts can regenerate is from seed, and some eucalypts can only regenerate this way. This strategy involves plants growing from seedlings into adults, setting seed which falls to the ground and forms a seed bank. A fire then removes the adult plants and new seedlings are generated from the seed bank that then repeat the cycle. The risk of this strategy is that a second fire will occur while plants are seedlings or saplings that haven’t reached a stage to make new seeds, thus removing the species because there is no back-up seed bank. Eucalyptus regnans, the mountain ash of Victoria and Tasmania which is the tallest flowering plant in the world, is an obligate seeder.

Eucalyptus angulosa, regeneration from seed, nearly 3 years after fire in Murrunatta Conservation Park, Eyre Peninsula. Photo P.J.Lang.

With that quick crash course in regeneration strategies of eucalypts we can now turn our attention to South Australian species and what we can expect to see from them after a fire. In 2006 Dean Nicolle from the Currency Creek Arboretum published a paper that summarised the regenerative strategy of every eucalypt species. Below are two tables that are a subset of Dean’s work and give details for each native South Australian eucalypt in the Kangaroo Island (Table 1) and Adelaide Hills (Table 2) 2019/2020 fire zones. (A “combination sprouter”, listed in the tables below, can regenerate from both, epicormic shoots as well as from lignotubers.)

The good news is that not one of those eucalypt species is an obligate seeder and so the threat of a second fire in the next few years removing a species from these areas is not high. The majority of eucalypts in these areas have lignotubers and should successfully regenerate. There are things we need to be observant about though. We think that these fires were extremely hot in some areas, perhaps hotter than has ever been experienced before. While eucalypts are adapted for fire we are uncertain at what maximum temperature plants can survive and regenerate. Past fires have indicated that if the thermal tolerance of species is exceeded then they will not regenerate.

Compiled by State Herbarium botanists Andrew Thornhill and Peter Lang.

Table 1. Regeneration strategies of eucalypts of Kangaroo Island.

Table 2. Regeneration strategies of eucalypts from the Adelaide Hills.