How Fungi Networks can help Bushfire Recovery

From recent observation, bushfire conditions are now more dangerous and probable than in the past, and the risk to people and property has increased. For well over 20 years, experts have been warning that climate change would increase the risk of extreme bushfires around the world. This warning was accurate. Scientists expect extreme fire weather in the future will continue to become more frequent and severe.

According to experts, the unprecedented bushfires that struck the east coast of Australia in the summer of 2020 have killed an estimated one billion animals across millions of hectares of Forest land.

Burnt landscapes with ashes of Forest resources and animal corpses demonstrate what climate-driven changes look like. But besides the visible effects of fire on the landscape, another invisible layer of devastating fire effects can be observable in the underground. This vast and complex underground world is symbiotically contributing to recovering and diversifying the Plant kingdom. And this underground world is the world of the Fungi, with an elaborate network called the Fungi Network.

The symbiotic relationship between Plants and Fungi

One of the most striking associations between Fungi and Plants is the establishment of Mycorrhizae. Mycorrhiza literally refers to the Fungal partner of a symbiotic relationship between vascular Plant roots and their partner Fungi. Almost 90% of all vascular Plant species have mycorrhizal partners. In this symbiotic relationship, the Fungal Mycelia use their extensive and expanded underground network of hyphae to channel water and minerals from the soil into the Plants. In exchange, the Plant supplies the products of photosynthesis to fuel the metabolism of the Fungus.

After the wildfires, the Forest landscapes can appear devoid of life, but a vast living network of Fungi is still there under the ash beds. According to experts, the world’s most land Plants have a symbiotic relationship with one specific group of Fungi, called Arbuscular Mycorrhizal in short AM Fungi. This means most Plants and AM Fungi depend on each other to survive and thrive.

Scientists observed that beyond nutrients, AM Fungi could affect all the aspects of living Plant ecology, such as Plant growth, seedling establishment, competition between different Plant species, and effective defense mechanism against herbivores. In astonishment, scientists discovered that the number of species and abundance of AM Fungi determine the success and diversity of Plants. And for the symbiotic relationship, many Fungi species without a Plant host can not survive long.

So, the responses of Plant and AM Fungi to fire are therefore deeply intertwined; the recovery of one is entirely dependent on the other. Despite the interdependent relationship between AM Fungi and Plants, experts and ecologists are only beginning to understand how fire affects Fungi networks and their role in hastening the ecosystem recovery following wildfires.

How fire affects the Fungi network

Obviously, the Fungi living near the soil surface are more susceptible to fire, and studies have shown that when fire passes over, some specific species of Fungi often get killed by the soil temperature.

Fungi further below the surface are relatively more protected, and scientists are assuming that they may provide the nuclei for recovery. But Fungi surviving without the supply of nutrients is only half the battle. When the vegetation on the surface gets removed by the fire, it suddenly stops providing the necessary fats and sugar which nourishes the underground Fungi world.

Scientists observed another challenge which the underground Fungi world faces in the aftermath of wildfires. After burning the landscapes, fire changes the soil chemistry, such as changes in soil carbon, soil acidity, soil water, and nutrient dynamics. For instance, scientists found that less diversity of AM Fungi can be observed in the soil with more acidity.

In 2017, scientists meta-analyzed 29 studies on the same subject and found that the combination of sudden high temperatures and changed conditions affects the underground Fungi world. According to the analysis, wildfires reduces about 28% of the total number of Fungal species.

Functions of Fungi in the recovery of the ecosystem

Xingjia Xiang of State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, in 2015 showed that when the fire hits the Fungal community loses less resistant species like Arbuscular Mycorrhizal Fungi.

This is important; previous studies have shown that different species of AM Fungi serve different functions to their hosting Plants. Some are more helpful with creating defense mechanisms against diseases and herbivores, while others are better at providing and collecting nutrients.

Changes in the number and types of AM Fungal species can significantly determine how well Plants will recover and can affect the whole ecosystem after the fire. For example, Plants could grow slower if the Fungi supporting hosting Plants nutrients and minerals are reduced by fire.

Understanding the specific function of a specific AM Fungi species is like knowing, pushing which button will give the Plants ability to grow faster with a stronger defense system. This knowledge is particularly important to Plants in times of ecological stress, which can drastically change the ecosystem in harsh post-fire landscapes. But while we know how to protect and take care of Plants and animals after the wildfire, we know very little about how to help AM Fungi communities to recover from the wildfire or if external help is even necessary.

So, in this context, helping Fungi help ecosystems. Lena Neuenkamp and her research team in 2019 showed that reintroducing specific AM Fungal communities as biofertilizers to disturbed and degraded landscapes can increase Plant diversity by around 70%. The team observed that reintroduction of certain AM Fungal communities within a certain location encourages the recovery of native Plants of the area and suppresses invasive weeds.

The research team concluded that taking a similar approach and actively bringing back Fungi into fire-affected environments could ensure a more rapid and complete recovery of native vegetation. They further suggest that the recovery of native vegetation could also contribute to the survival of endangered Plant species threatened by the fires. However, they pointed out that it is important to understand and consider the functions and availability of AM Fungi communities, and they should be reintroduced if they are present in the local area and suited to support recovering Plant communities.

Conclusion

According to the research results, the invisible underground Fungi world can form a fundamental component of the fire recovery mechanism. But there is so much more to learn about these complex ancient relationships. A better understanding of the Fungi world can assist humanity in the battle with climate change. But in this invisible world of Fungi and microbiome, the researchers are only beginning to scratch the surface.

References

1. Day, N. J., et al. (2019). Wildfire severity reduces richness and alters composition of soil fungal communities in boreal forests of western Canada. Wiley Online Library, [online] Volume, 25(7), p. 2310-2324. Available at: https://doi.org/10.1111/gcb.14641 [Accessed 30th August 2021].
2. Dooley, S.R., Treseder, K.K. (2012). The effect of fire on microbial biomass: a meta-analysis of field studies. Biogeochemistry, [online] Volume, 109, p. 49–61. https://doi.org/10.1007/s10533-011-9633-8 [Accessed 30th August 2021].
3. Dove, N.C., Hart, S.C. (2017). Fire Reduces Fungal Species Richness and In Situ Mycorrhizal Colonization: A Meta-Analysis. fire ecology, [online] Volume, 13, p. 37–65. Available at:  https://doi.org/10.4996/fireecology.130237746 [Accessed 30th August 2021].
4. Frew, A., Powell, J.R., Allsopp, P.G. et al. (2017). Arbuscular mycorrhizal fungi promote silicon accumulation in plant roots, reducing the impacts of root herbivory. Plant and Soil, [online] Volume, 419, p. 423–433. Available at: https://doi.org/10.1007/s11104-017-3357-z [Accessed 30th August 2021].
5. Frew, A., Powell, J.R., Allsopp, P.G. et al. (2017). Arbuscular mycorrhizal fungi promote silicon accumulation in plant roots, reducing the impacts of root herbivory. Plant and Soil, [online] Volume, 419, p. 423–433. Available at: https://doi.org/10.1007/s11104-017-3357-z [Accessed 30th August 2021].
6. Hart, S. C., et al. (2005). Post-fire vegetative dynamics as drivers of microbial community structure and function in forest soils. ScienceDirect, [online] Volume, 220(3), p. 166-184. Available at: https://doi.org/10.1016/j.foreco.2005.08.012 [Accessed 30th August 2021].
7. Hiiesalu, I., et al. (2014). Species richness of arbuscular mycorrhizal fungi: associations with grassland plant richness and biomass. New Phytologist Foundation, [online] Volume, 203(1), p. 233-244. Available at: https://doi.org/10.1111/nph.12765 [Accessed 30th August 2021].
8. Hodge, A., et al. (2010). Nutritional ecology of arbuscular mycorrhizal fungi. ScienceDirect, [online] Volume, 3(4), p. 267-273. Available at: https://doi.org/10.1016/j.funeco.2010.02.002 [Accessed 30th August 2021].
9. Jimenez-Pinilla, P., et al. (2016). Temporal changes in soil water repellency after a forest fire in a Mediterranean calcareous soil: Influence of ash and different vegetation type. ScienceDirect, [online] Volume, 572(1), p. 1252-1260. Available at: https://doi.org/10.1016/j.scitotenv.2015.09.121 [Accessed 30th August 2021].
10. Moora, M., et al. (2014). Anthropogenic land use shapes the composition and phylogenetic structure of soil arbuscular mycorrhizal fungal communities. Oxford Academic, [online] Volume, 90(3), p. 609-621. Available at: https://doi.org/10.1111/1574-6941.12420 [Accessed 30th August 2021].
11. Sharples, J.J., Cary, G.J., Fox-Hughes, P. et al. (2016). Natural hazards in Australia: extreme bushfire. Climatic Change, [online] Volume,139, p. 85–99 https://doi.org/10.1007/s10584-016-1811-1 [Accessed 30th August 2021].
12. Tedersoo, L., et al. (2020). How mycorrhizal associations drive plant population and community biology. Science, [online] Volume, 367, Available at: https://science.sciencemag.org/content/367/6480/eaba1223.full [Accessed 30th August 2021].
13. Wipf, D., et al. (2019). Trading on the arbuscular mycorrhiza market: from arbuscules to common mycorrhizal networks. New Phytologist Foundation, [online] Volume, 223(3), p. 1127-1142. Available at: https://doi.org/10.1111/nph.15775 [Accessed 30th August 2021].
14. Xiang, X., Gibbons, S.M., Yang, J. et al. (2015). Arbuscular mycorrhizal fungal communities show low resistance and high resilience to wildfire disturbance. Plant and Soil, [online] Volume, 397, p. 347–356. Available at: https://doi.org/10.1007/s11104-015-2633-z [Accessed 30th August 2021].