Alpine Ash, a quintessential tree of the Australian Alps, which is restricted to higher elevations, mostly between 900 m and 1,450 m in Victoria and southern New South Wales, has had 84% of it’s range burnt since 2002. Fires have burnt 84% of the bioregion’s 355,727 hectares of alpine ash forest, with 65% burnt in 2002/03 in the north of the Alps, 30% burnt in 2006/2007 in the south, and a smaller area (2%) burnt in 2009. Four per cent of the forest area was burnt twice within five years. And last summer, additional areas were burnt in the east of the state. This has led to scientists warning that large sections of Alpine Ash forests are on the verge of collapse.
And world renowned forest researcher David Lindenmayer says that only 0.47% of old growth alpine ash is left in the Central Highlands of Victoria. Let that sink in for a moment. The amount of old growth in the east and north east of the state is not known. But these areas have been heavily burnt in recent years, with ‘at least’ 10,000 ha of the forest community on the verge of collapse.
According to a research paper called Ashes to ashes: increased fire frequency threatens alpine ash forests (2015) by Prof David Bowman and Dr Brett Murphy for The Landscapes and Policy Hub (available here):
Alpine Ash is identified as being particularly vulnerable to increased fire frequency. Alpine ash is an ‘obligate seeder’ — a fire-dependent plant that is readily killed by fire but regenerates prolifically from seed after fire and matures rapidly so that it can reproduce before the next fire. Trees can reproduce after 20 years, can live for more than 200 years, and can reach 90 metres in height. Mature trees can tolerate low-intensity fires due to the thick bark on the lower third of the trunk. Plants are not adapted to fire, per se; rather, they are adapted to fire regimes, which are characterised by the frequency, intensity, seasonality and type (for example, surface or crown) of fire. The life cycle of obligate seeders is coordinated around the fire-free intervals of the fire regime to which they are adapted. If their life cycle gets out of sync with the fire regime, they may not survive. More frequent severe fires could prevent regenerating young plants reaching maturity, resulting in landscape-wide loss of obligate-seeder forests around the world, including the alpine ash forests in the Australian Alps bioregion. This transformation in the landscape may be irreversible because, as the mature trees die, the altered understorey becomes more flammable (the regenerating trees being highly flammable). Also, when mature trees burn, the carbon stored in the trees is released into the atmosphere.
84% of the bioregion’s alpine ash has been burnt since 2002. Since 2000, almost 90% of the Australian Alps bioregion has been burnt by large wildfires. These fires have burnt 84% of the bioregion’s 355,727 hectares of alpine ash forest, with 65% burnt in 2002/2003 in the north of the bioregion, 30% burnt in 2006/2007 in the south, and a smaller area (2%) burnt in 2009. Four per cent of the forest area was burnt twice within five years. Fire severity was high (canopy entirely scorched) in about half of the burnt area of alpine ash forest.
In other words, this community of trees is being absolutely hammered by logging and fire.
There is a very good chance that we will see the end of this species in it’s mature/ older form in our lifetime.
Check here for details on the Victorian government’s reseeding program.
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