A world-first study led by Australian National University ecologist Professor David Lindenmayer has found gaps in the forest canopy allow the forest floor to dry out, increasing flammability by as much as 50 per cent in some cases.
The team looked at the impacts of industrial logging in moist forests across the world, including tropical rainforest, North America and Russia's wet conifer forests and mountain ash forests in southern Australia.
Professor Lindenmayer said the study had ''huge implications'' for future forest management and bushfire control in Australia.
''We can't ignore the risks, particulary in the face of climate change. These trends are occurring in moist forests right across the planet. There are no excuses, no reason to claim Australia's forests are somehow different. We've got to face up to reality and do some serious thinking,'' he said.
The study, published by the international journal Conservation Letters found logging altered forest fire regimes by changing the amount, type and moisture content of fuels. The paper's four authors include University of Maine conservation biologist Malcolm Hunter and Canadian Forest Service senior research scientist Philip Burton.
Professor Lindenmayer said the team wanted to investigate whether logging made forests more or less fire-prone. ''This is a question that gets debated after any big bushfire, and we usually hear all sorts of uninformed opinions from lobby groups. So we said, 'Right, let's do some serious science.' We looked at moist forests because fires usually occur at a relatively lower frequency than dry forests.''
The team found logging changed moist forest microclimates, drying out understorey vegetation and leaf litter. Roads built for logging access also increased the number of ignition points for fires, and the area of forest edge susceptible to drying.
The study said research published almost 15 years ago, found clear-felling of moist forests in southern Australia led to ''the development of dense stands of regrowth saplings that created more available fuel'' than if the forests were not clear-felled. Professor Lindenmayer, who has spent more than 30 years doing research in the mountain ash forests near Marysville, said decades of logging had ''created a legacy of ecosystem disturbance that will be felt for centuries''.