Leading ecologists say decades of underspending on environmental research mean governments will likely struggle to assess the impact on wildlife from the huge bushfires let alone develop effective recovery plans.

The assessment comes days after the Victorian and NSW governments developed initial responses to the fires, and the Morrison government declared as many as 100 threatened species had lost at least half their habitat.

The critically endangered smoky mouse may have lost a quarter of its habitat in NSW and potentially more in Victoria because of the fires. Credit:AAP

The Australian Conservation Foundation said federal Coalition governments had sliced 40 per cent off the Environment Department's budget since 2013, with more loss of staff likely once it is merged with the Department of Agriculture.

"Governments have viewed the environment as a millstone...dragging back progress," Richard Kingsford, director of the University of NSW's Centre for Ecosystem Science, said.