Buffalo exit didn't boost Kakadu growth

The lack of wild buffalo is not behind an increase in woody vegetation in Kakadu National Park, according to researchers who blame "larger issues" such as increased rainfall and CO2 levels.

It has been widely assumed that the eradication of buffalo has played a major role in the thickening of woody cover in the world heritage-listed park.

But researchers from Charles Darwin University's School for Environmental Research have found that although the density of wooded vegetation on the floodplain has increased, the removal of buffalo is not a major cause.

Published in the Journal of Biogeography, their ground-breaking paper examined the ecological effects on Kakadu over the last four decades.

"We wanted to see what has happened with woody vegetation in Kakadu over the last 40 years," said Dr Lynda Prior.

"It has increased significantly since the 1980s and the obvious conclusion was that it was the effect of removing the buffalo."

Wild buffalo built up to high densities in Kakadu until 1985, after which a control program almost eliminated the animals.

A buffalo farm was established within Kakadu in 1990 to supply meat to traditional owners to compensate for the loss of the animals.

Professor Davis Bowman said the study looked at both the flood plains and eucalypt savanna, comparing trends when buffalo were high-density, farmed or wiped out.

"The correlation between the densities of feral buffalo and the prevalence of woody cover in Kakadu National Park was weak," he said.

"Rather, the observed increases in woody cover concords with regional trends and may be related to an increased level of atmospheric CO2, increasing rainfall and changing fire regimes during the study period."

Dr Prior said it was important for the future of the park that researchers and governments were aware of the complex nature of the environment.

"We think there are other factors at play," she said.

"It just makes it a little more complex. It was easy to leap to the conclusion that it was because of the buffalo but it is really these larger trends that are playing a part.

"It's really important to monitor what's happening and try to understand why it's going on."