In a previous blog, we introduced three species that often occur after fire.
Other attractive species likely to be seen on Kangaroo Island and elsewhere are branched everlasting, Coronidium adenophorum (F.Muell.) Paul G.Wilson, purple daisy bush, Olearia rudis (Benth.) Benth., as well as ironstone mulla mulla, Ptilotus beckerianus (F.Muell.) F.Muell., this last species appeared in hundreds in post 2007 fire scars near the Ravine des Casoars.
Coronidium adenophorum, Olearia rudis & Ptilotus beckerianus (from LEFT to RIGHT). Habit of plants with flowers and new seedling (for O. rudis). Photos: SA Seed Conservation Centre.
Orange disc fungus, Byssonectria fusispora, surrounded by mosses. Photo: D. Catcheside.
Fungi are essential in all ecosystems, acting as recyclers, helpers of almost all plants and improving soil health. After fire, much of the organic material in soils may have burnt, leaving a blackened mass of fine, silty particles and ash. The ash is highly alkaline and unfavourable for plant regrowth. The fungi help in restoration of soil health, as recyclers of burnt litter and wood and as partners with plants in re-establishing the vegetation.
Two disc fungi, orange Pulvinula archeri, brown-lilac Peziza tenacella. Photo: D. Catcheside.
A group of fungi whose spores germinate almost immediately after fire are the disc fungi (e.g. Peziza and Pulvinula, image above). These act as colonisers. Their fine thread-like hyphae bind soil particles, stabilising the soil and helping to reduce erosion. They change the highly alkaline ash (with a pH of up to 10) to soils which are approximately neutral (pH 7). Structurally, the hyphae form a network, a ‘scaffolding’, improving soil aeration and water percolation. The often dense carpets of disc fungi covering the bare soil not only reduce erosion but also provide protection for small plants such as mosses, grasses and herbs (see top image). As the fungal hyphae and plant roots grow their developing networks increase movement of gases and water through the soil. Other groups of fungi are saprotrophs, breaking down and recycling burnt litter and wood.
Coprinellus angulatus, a saprotrophic fungus (left image). Stereum hirsutum, a saprotroph on wood (right image). Photos: D. Catcheside.
Pam Catcheside and Danielle Calabro with a sclerotium of Laccocephalum mylittae. Photo: D. Catcheside.
There is a definite succession of fungi after fires.
Amongst the first to appear, often only a day or two after fire, are strange, hard, mushroom-like fungi with pores, not gills in the genus Laccocephalum (see image at bottom of this post). Their fruit-bodies grow from an underground storage-organ called a sclerotium. The sclerotium of Laccocephalum mylittae, native bread, was eaten by Aborigines (image on right). It may weigh up to 20 kg.
Yellow, orange, brown and black disc fungi appear. Some species fruit only in the first year after fire, others in the second and some for several years. As litter builds up recycling fungi break it down returning nutrients to the soil.
Mycorrhizal fungi (e.g. from the genus Laccaria, image below), which form symbiotic relationships with plants become re-established, collecting nutrients and water for the partner plant and receiving energy-giving sugars in return. Gradually, the web of life with all its complex communication systems regains momentum, habitats are re-established, insects and other animal life return and natural cycles continue.
We observed this pattern after the 2007 bushfires on Kangaroo Island. Since Flinders Chase National Park is relatively self-contained, weeds which often invade bare areas did not threaten the native systems. Keeping out weeds after a fire is a major concern.
Laccaria sp., a mycorrhizal fungus. Photo: D. Catcheside.
Another concern is that it takes time for the bush to re-establish itself, some studies showing that it takes at least five years but this time lapse varies with different habitats. We have found that most groups of fungi have returned to pre-fire levels. It is now 12 years since the last major fires on the island and Kangaroo Island has shown itself to be resilient.
Laccocephalum sp. showing swollen sclerotium. Image of herbariumspecimen PSC3033 before drying. Photo: D. Catcheside.
Kalotas, A.C. (1996). Aboriginal knowledge and use of fungi. In Orchard, A.E. (Exec. Ed.), Mallett, K. & Grgurinovic C. (Vol. Eds.). Fungi of Australia, Vol. 1B: Introduction-Fungi in the Environment. (Australian Biological Resources Study, Canberra).
Flinders Chase is likely to transform into floral wonderland in the springs of 2020 and 2021. In particular many short lived ephemerals will germinate from dormant seed, grow quickly, flower and then disappear in a year or two until the next fire. Some good examples are:
Kangaroo Island cress — Irenepharsus phasmatodes Hewson, has small white, but strongly fragrant flowers, it occurs only on Kangaroo Island.
Irenepharsus phasmatodes growing on Kangaroo Island. Photo: SA Seed Conservation Centre.
False tobacco — Apalochlamys spectabilisJ.H.Willis, has pungent smelling leaves and large spike of many flowers, it grows in dunes and other sandy soils.
Apalochlamys spectabilis. Photos: SA Seed Conservation Centre & R. Taylor (inset).
Oondooroo — Solanum simile F.Muell, has distinctive lush green foliage and blue flowers, it is often associated with mallee eucalypt woodlands.
Solanum simile at Mount Remarkable National Park. Photo: SA Seed Conservation Centre.
Throughout the decades the staff at the Botanic Gardens and State Herbarium have collected and curated plant specimens from all over the State. This enables the State Herbarium to document the native and introduced plant species that occur in South Australia.
The Herbarium’s collections contains more than one million plant specimens from all over the world; of these, more than 600,000 are South Australian plant specimens. In the early 2000s the State Herbarium of South Australia along with all other Australasian herbaria catalogued their Australian native plant collections and shared the data via a free online database, called the Australasian Virtual Herbarium.
This publicly available data based on the physical specimens in the herbarium collection allows current and future botanists to understand our flora in an ever growing way. Here, I have generated biodiversity assessments of the South Australian flora presented as maps of high diversity areas using all of the information in these collections.
By dividing South Australia into 10km grid cells, it is possible to calculate, which areas in the State contain the greatest number of plant species (richness), and which ones contain the greatest number of plants that are unique to South Australia (endemism). These maps show that both the Adelaide Hills and Kangaroo Island are two significant floral diversity areas for South Australia.
The maps present results that display one of the reasons why the fires that occurred in late 2019 and early 2020 may be a concern for the future of South Australia’s plant biodiversity. We can visually observe some of the reasons for concern by overlaying the locations of the past summer’s fires onto maps of South Australian plant species richness and South Australian plant endemism (see below, using data fromNASA FIRMS).
The figure below is a map of South Australian plant species richness. The majority of areas that contains the most species (i.e. the areas in red) is higher mountain regions such as the Flinders Ranges and the Adelaide Hills, as well as the Eyre Peninsula, Kangaroo Island, and the south-east.
A species richness analysis of South Australian plants using plant records from all Australasian herbaria collected since 1802. Grid cells are 10 × 10 km2. Where the fires of 2019/2020 occurred are the brown dots. The inset box shows Kangaroo Island and the Adelaide Hills and the dots represent fire areas of December 2019 and early January 2020. It can be seen that many of the high plant diversity cells of the western and northern parts of Kangaroo Island have been severely impacted by the fires.
Zooming in on the fire areas of Kangaroo Island and the Adelaide Hills, it can be seen that the fire has occurred in areas that contain some of the highest number of plant species in the State. The Adelaide Hills fires have burnt across a smaller number of the map grid cells in comparison to the Kangaroo Island fire. The Adelaide Hills fires still occurred in areas of high plant diversity.
The Kangaroo Island fires burnt across the majority of species rich cells on the western half of the island, but it is also important to note that many of the species that grow on the western end of Kangaroo Island are very different to those that grow on the eastern side of the island (which was mainly unburnt).
To analyse this in more detail, the second measure becomes important, i.e. endemism.
South Australia has three significant concentrations of plant endemism – Kangaroo Island, Adelaide Hills and south-eastern South Australia. As can be seen in the figure below, the map cells with significant endemism in the western region of Kangaroo Island have been impacted by the fires. Part of the significant Adelaide Hills endemism has been burnt in the fires. The endemism area in the South-East of the State has not been affected by fire so far.
An endemism richness analysis of South Australian plants using plant records from all Australasian herbaria collected since 1802. Grid cells are 10 × 10 km2. Where the fires of 2019/2020 occurred are the brown dots. The inset box shows Kangaroo Island and the Adelaide Hills. South Australia has three significant concentrations of plant endemism – Kangaroo Island, Adelaide Hills and South-eastern South Australia. As can be seen the significant endemism cells of western Kangaroo Island have been impacted by the fire. Part of the significant Adelaide Hills endemism has been burnt in the fires.
It will be important that during the remainder of this autumn, no more fires occur in areas of high diversity or endemism. In particular, fire in the south-eastern part of South Australia would be problematic for plants that are unique to South Australia, even though some of these plants occur in Victoria on the other side of the State border.
Recovery of native vegetation
There have been significant bushfires in the past, e.g. there was a major fire on Kangaroo Island in 2007 that burnt most of the western side of the island. The Ash Wednesday fires of 1983 in the Adelaide Hills was also a significant fire event. In those instances the vegetation recovered over time.
As the cooler and wetter weather in autumn and winter continues, plants will begin to recover and germinate. Many Australian natives are adapted to recovering from fire and the eucalypts will soon start sprouting leaves from their epicormic buds or lignotubers, while grass trees will send up new shoots. Some plants are advantaged by fire and there will be mushrooms, mosses, sundews, and orchids that will appear over the forest floor in numbers.
As for some of the rare and endemic species on Kangaroo Island, we won’t be able to say for certain until it is safe enough to re-enter the areas where they occur, and probably until next spring, when flowering begins and plants can properly be identified; or even a year or two after that.
We have plant lists for many parts of Kangaroo Island which have been collated over the years through the work of the Kangaroo Island community, students, State Herbarium staff, the S.A. Seed Conservation Centre and many volunteers. These lists and locations will assist with understanding the recovery processes of the fire affected areas over the coming years.
Remarkable Rocks on Kangaroo Island post-fire (10 Jan. 2020). Photo: DEW.
Written by Andrew Thornhill, State Herbarium of South Australia & The University of Adelaide.
Xanthorrhoea semiplana subsp. semiplana flowering in Cox Scrub Conservation Park after fire. Photo: D. Murfet, SA Seed Conservation Centre.
Fire has been part of the Australian environment for a long time. Parts of the country have burned very regularly (such as grasslands, heathlands, savannahs), while other areas experiences fire rarely (e.g. tall mountain ash forests in Victoria), or almost never (e.g. rainforests in the tropics or some alpine areas in Tasmania).
Most Australian plants are fire-adapted and have strategies to cope with fire. Some re-sprout after fire, with green shoots bursting from blackened stems; for others, fire stimulates flowering, while other species take advantage of bushfires to germinate.
Well known examples of plants that survive fires well are:
There are also some fungi and mosses that will respond quickly to fires. However, there are also species that take a long time to recover or never do. For example,mistletoesand other epiphtes will not re-sprout when the host tree burns and many cryptogams (lichens, fungi & mosses) will take decades to re-establish importantsoil crusts.
Should fires occur too frequent, regeneration is also hampered, as the soil seed bank will be depleted. The severity of fires also affects the ability of plants to recover.
Post-fire landscapes need time to recover, so we need to adopt a “wait and see” approach. Often one, two or even three growing seasons are necessary to be able to establish, which species have recovered from fire and which ones not. While there will be much regeneration in the burned areas, identification of seedlings and young plants is very difficult and often botanists need to wait for these to flower to be certain of their identity.
Removal of weeds and prevention of weed spread is also very important to help native vegetation to thrive after a fire. But again, weed identification can be very difficult if there are only small seedlings present. Often, it may be better to wait until potential weeds grow larger or even until they start flowering, so their identity can be confirmed. This will prevent the “weeding” of native seedlings, i.e. of exactly the plants that we want to come back (see also AMLR fact sheet on woody weeds and fire; 2.3mb PDF).
More information can be found on our list of fire-related publications and websites. Soon, we will also post further blog articles about the fire response of certain species and groups of plants.
Banksia ornata cone releasing seeds after fire. Photo: D.Murfett, SA Seed Conservation Centre.