Fires, Forests and Futures: The ANU Westoby Lecture

Summary

This paper addresses management and policy issues arising from the 2009 and other recent fires that burnt the iconic ash-type forests of eastern Victoria. After sketching a general framework for an analysis of sustainability, the paper elaborates the results of a simulation study on seed collection and storage (to be published separately), especially in relation to the risks posed to the ash-type state forests by major fires. These forest types are notably fire sensitive and easily killed by fires of moderate or even mild intensity. They are also cyclical in the extent of seed production and do not set seed in commercial quantities for the first 20 years of life. If seed collection and storage is restricted to ‘low’ levels until 2050, the risks are substantial, involving probabilities over 90% for alpine ash, implying insufficient seed to permit artificial regeneration of those burnt areas that have not regenerated naturally, whether climate change occurs or not. Those risks can be reduced substantially by higher levels of seed collection, but even at ‘median’ levels the probabilities may approach 40% under high rates of climate change. The simulated outcomes for mountain ash state forests are much less severe but the impacts of high rates of climate change are still great enough to cause discomfort.

Data for the ash-type conservation reserves were not available but descriptive reports indicate that the risks for both forest types in the conservation reserves may be very high, as many of the old-growth stands in the national parks (often closed water catchments) were severely burnt in the 2003, 2006–2007 or 2009 fires. The risks posed by fire in the next 20 y to water quality and biodiversity are very likely to be material.

This leads to advocacy of active management measures that include: (1) a well-equipped workforce, (2) removal and salvage of fire-killed trees along access roads, (3) seed collection and artificial regeneration in conservation reserves, (4) strategic swaps of age classes to the advantage of both tenures, (5) regrowth thinning for habitat management and water production, (6) better access for fire management and more fuel reduction burning and (7) strategic orientation of harvest areas.

In the past, the conservation versus development debate about forests has been a ‘zero-sum game’. Whatever one side gained the other lost, as areas were transferred from one designation to the other. That approach neglects the role of a third player, Mother Nature, especially relating to fire, and this means that a joint approach to addressing the risks is desirable.

The ash-type conservation reserves are as much about multiple uses as are state forests. Some uses are common to both, some excluded from one and not the other, and some that vary by degree rather than absolute exclusion in one or the other. We face a future in which there is a material risk that we will lose most or all of these ash-type forests, not over millennia, but in the next 60 y. We can decide to do nothing and accept that loss, or we can engage in active management to conserve their values and uses by reducing the risks across both tenures.

Keywords:

• fire
• risk
• seed production
• seed collection
• forest management
• planning
• Monte Carlo method
• Eucalyptus regnans
• Eucalyptus delegatensis