(Iran's Environment News Agency)The rapid loss of foraging animals such as bilbies, bandicoots and potoroos since the European colonisation of Australia has been linked to ecosystem decline, owing to the role they play in keeping land healthy.

A new study led by Murdoch University has found that digging mammals play a key role in increasing nutrient turnover and water infiltration in soil, as well as dispersing seeds.

Animals such as wombats, which dig holes to live in, are credited with breaking up hard soil and recycling organic material, such as fallen leaves, through the earth.

These mammals effectively plough furrows in the ground for seeds to fall into, increasing the chance that the seeds will become healthy plants. They are also credited with reducing fire risks by taking litter and debris underground with them.

"We'd say that these animals increase soil health and nutrient turnover, leading to more vibrant, healthier plants," Trish Fleming, associate professor at Murdoch University, told Guardian Australia.

"These animals have suffered major losses over the last 200 years, so it's interesting to think about how landscapes may have looked with more of them present.

"We have an idea in certain predator-proof areas, which are really very different ecosystems. There is less leaf litter lying around and plants have increased growth rates."

Several native mammal species have suffered sharp declines since the European arrival, with Australia holding the unenviable status of being one of the world's worst countries for mammal extinctions.

The woylie, a small mouse-like marsupial, once roamed across 60% of Australia but has now been reduced to a few thousand survivors in pockets of Western Australia. The UN, which lists it as critically endangered, says the species has "no clear signs of population recovery".

Bilbies once covered 70% of Australia. Now one subspecies has become extinct and another is endangered.

Certain types of bandicoot are also vulnerable, while the Gilbert's potoroo is Australia's most endangered mammal, with fewer than 50 believed to exist in the wild.

The trapping and killing of the animals by early settlers, in an attempt to protect crops from their digging, have been blamed for the declines, along with habitat loss and disease.

The spread of feral species such as pigs, rabbits and cats have also contributed to the mammals' woes. Crucially, these introduced species do not play the same role in maintaining ecosystems as the mammals they have displaced.

"When feral pigs dig up soil, they destroy large habitats, rather than the neat, discreet foraging of these other mammals," Fleming said.

"The diggings of animals like rabbits involve more weeds and changing the dynamics of ecosystems in ways that aren't beneficial.

"We certainly have more questions than answers in how to turn this around. Some animals survive quite well being close to human habitation, such as bandicoots, which are reasonably resilient to dogs and cats.

"We have looked at reintroducing animals in order to protect the species but we haven't really thought about their roles in ecosystems."

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