Foxes Cats and truffles and trees

September brings spring and Biodiversity Month. It’s time to reflect on what was once, and is now and could be across Australia.   

Old Australia had sponge-like soils where ‘horses sand to the fetlock’. In New Australia soils are hardened, compacted and water repellent due to the loss of Aboriginal agriculture, the arrival of those hard-hoofed grazers, the sheep, cattle, pigs, goats, and horses and the explosion of foxes, wild cats and wild dogs. 

The soils of Old Australia forest floors also were once typically well-tilled and friable with high carbon content due to a complex relationship between the mycorrhizal (fungus root) truffle fungi that all eucalypts and most other tree species completely depend on to thrive, and the small native animals that spread the spores of these fungi. 

To reproduce the fungus makes fruiting bodies - truffles - which give off scents to attract some 30 species of Australian mammals including potoroos , bandicoots, bettongs, possum, native rodents, kangaroos, wallabies, pademelons, quokkas, bilbys, and wombats. In digging up their food the marsupials break hydrophobic soil crusts and bury bark and twigs.

In Old Australia these marsupials could turn over 60 tonnes of soil and debris per hectare per year. Soil was permeable to rain, soft and nutrient cycles active. In the New Australia foxes and cats have wiped out 30 species of small marsupial.

Soils are water repellent and fire fuel loads build up yearly. Floods and fire are vastly more destructive. Soil formation has stopped. New tree seedlings are not mycorrhized well and suffer, old paddock trees starve to death.

Biodiversity Month is a time to turn our attention to removing foxes, wild dogs and cats from our landscape.

Professor Tim Roberts is the director of the Tom Farrell Institute for the Environment, University of Newcastle

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