A program leader at the Bushfire Co-operative Research Centre and professor at Sydney University, Mark Adams, said there was a spike of prescribed burns after the 2001 bushfires.

The amount of bush cleared in burns since has varied greatly, reaching a peak of more than 65,000 hectares, before being reduced to 23,000 hectares in 2006-07.

"We've seen this pattern before, that the amount of burning just falls away the longer we have without bushfires," he said.

"There's always opposition to prescribed burning and agencies are not immune to people ringing up and saying, 'you're not allowed to burn in my backyard'."

Environmental laws were too onerous for landowners to protect their property.

A spokeswoman for national parks said that almost 20,000 hectares of bush had been cleared since July 1 in prescribed burns.

Last year, the amount was more than 60,000 hectares.

A Rural Fire Service spokesman said hazard reduction procedures depend on variables including the weather and landscape.

"Sometimes a hazard reduction will occur on a relatively small and difficult piece of land but secure a high number of properties."