By Natasha Tay. On 3rd March 1973 at the meeting of the International Union for the Conservation of Nature (IUCN), representatives of 80 countries agreed to protect animals and plants from being excessively and unsustainably traded and exploited. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was thus created and 49 years later, 184 parties have signed this international agreement, protecting more than 37,000 species of animals and plants.

Today, we celebrate 3rd March as the World Wildlife Day – a day to celebrate and raise awareness of the world’s wild animals and plants. The theme for 2022 is “Recovering key species for ecosystem restoration”.

The role of key species in maintaining and restoring ecosystems has been a research interest of westernWEB over the years.  Identified as ecosystem engineers, digging mammals have the ability to profoundly modify their environment, creating resources for other species. Conserving or even translocating these diggers into degraded habitats may contribute to ecosystem restoration.

Animals that dig for food and shelter were once described as common throughout Australia. Today, around half of our digging species are now extinct or under conservation threat¹. In areas where we have lost digging mammals, we have also lost the important ecosystem services they carry out. Loss of these important animals has detrimental impacts on the health and functioning of our ecosystems.

Through their digging, diggers such as bandicoots, bettongs and bilbies turn over soil (called ‘bioturbation’). Bioturbation of soil can improve soil health by mixing up the organic matter, therefore increasing nutrient cycling. Woylies and bandicoots can excavate between 2.7–4.8 tonnes of soil per year while looking for fungi, roots and invertebrates^2,3,4 – that’s as much as an Asian elephant weighs! Pretty impressive for animals that are only about 1.5 kg themselves.

Bilbies and boodies are even heavier hitters – these species dig extensive burrows and warrens and are estimated to move 30 tonnes of soil per year⁵. On top of capturing organic matter and promoting nutrient cycling, bioturbation alters soil texture and water infiltration, creating more favourable areas for seedling germination^1,6.

Many digging mammals are mycophagous – these guys like their mushrooms and truffles. Here in suburban Perth, we are lucky to still have quenda roaming around foraging for fungi and other tasty treats. Our latest research⁷ shows that quenda dig up and eat a great diversity of fungi, transporting beneficial fungi spores in their poo and dispersing them throughout our urban bushland.

A third (30%) the fungi species found in quenda poo are “mycorrhizas”. Mycorrhizal fungi form beneficial relationships with plant roots, including those of our iconic eucalypts, improving their absorption of important nutrients and water for plant growth.

Quenda clearly have the potential to influence ecosystem processes through their digging and foraging. The combination of soil bioturbation and mycorrhizal fungi dispersal add an important element with flow-on effects for urban bushland health.

If you see a quenda in your travels this World Wildlife Day, be sure to thank it for its superb work as an ecosystem engineer and nature’s little gardener.

References

1. Fleming, P.A., Anderson, H., Prendergast, A.S., Bretz, M.R., Valentine, L.E. & Hardy, G.E.S. (2014) Is the loss of Australian digging mammals contributing to a deterioration in ecosystem function? Mammal Review, 44, 94-108.
2. Halstead, L.M., Sutherland, D.R., Valentine, L.E., Rendall, A.R., Coetsee, A.L. & Ritchie, E.G. (2020) Digging up the dirt: Quantifying the effects on soil of a translocated ecosystem engineer. Austral Ecology, 45, 97-108.
3. Valentine, L.E., Anderson, H., Hardy, G.E.S. & Fleming, P.A. (2012) Foraging activity by the southern brown bandicoot (Isoodon obesulus) as a mechanism for soil turnover. Australian Journal of Zoology, 60.
4. Garkaklis, M.J., Bradley, J.S. & Wooller, R.D. (2004) Digging and soil turnover by a mycophagous marsupial. Journal of Arid Environments, 56, 569-578.
5. Newell, J. (2008) The role of the reintroduction of Greater Bilbies (Macrotis lagotis) and Burrowing Bettongs (Bettongia Lesueur) in the ecological restoration of an arid ecosystem: foraging diggings, diet, and soil seed banks. PhD, University of Adelaide.
6. Dundas, S.J., Hopkins, A.J.M., Ruthrof, K.X., Tay, N.E., Burgess, T.I., Hardy, G.E.S.J. & Fleming, P.A. (2018) Digging mammals contribute to rhizosphere fungal community composition and seedling growth. Biodiversity and Conservation, 27, 3071-3086.
7. Hopkins, A.J.M., Tay, N.E., Bryant, G.L., Ruthrof, K.X., Valentine, L.E., Kobryn, H., Burgess, T.I., Richardson, B.B., Hardy, G.E.S.J. & Fleming, P.A. (2021) Urban remnant size alters fungal functional groups dispersed by a digging mammal. Biodiversity and Conservation.