Memories of Black Saturday reminder that our forests need time to grow

Friday, January 13, 2017

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We did not know it was coming until a spot fire blazed red a hundred metres away. Flames crackled through wattle and blackberry thickets; gum trees exploded with a woomph; and a dog and a black mountain possum dashed towards us in terror. 

The inferno raged for hours around our mud brick cottage at Granton, near Narbethong, devouring the crown land forest alongside our block and incinerating the garden, sheds and neighbouring homes. The next morning brought the full horror of a silent, charred landscape; the news of deaths; and Marysville reduced to smouldering ruins. Eight years on, the forest and garden have re-greened, most bird species have reappeared, and white tree skeletons that poke through the tangle of regenerating bush have their beauty. The surrounding mountains are shrouded by a ghostly fuzz: vast areas of dead mountain ash trees reaching above the re-growth.

The combined impact of logging and fire means swathes of ecologically rich mountain ash forest has been converted to immature, fire-prone areas. Photo: Paul Rovere

Since Black Saturday we've been blessed with eight years of reasonable rainfall, but with climate change, more droughts and large-scale fires are inevitable. With two or three dry months and baking summer temperatures, the bush will be tinder dry: it could easily happen again. But what if government policy, in its support for industrial-scale logging, is ignoring Australian and international fire research, thereby putting local communities and remaining forests at increased risk?

A detailed study carried out by researchers at Melbourne University and scientists at the ANU (Taylor et al, 2014) indicates that intensive clear-fell logging significantly increases the severity of bushfires in mountain ash forests. Their spatial analysis of 10,000 sites in Central Highlands forests that were burned on Black Saturday found that tree age was more significant than other variables in contributing to fire severity. The most severe fires that consumed tree crowns and forest canopies occurred in stands of young mountain ash between seven and 36 years of age. In stands more than 36 years old, the risk of crown fire decreases because the trees are taller and gaseous eucalyptus fuel is more dispersed. Older forests are less dense and a moist understorey including rainforest plants, ferns and mosses, acts as a retardant.

It follows that the severity of the 2009 fires was exacerbated by the predominance of young mountain ash trees, the legacy of 30 years of widespread clear-fell logging in the region. An estimated 30 per cent of mountain ash forests in the Central Highlands had been clear-felled before 2009 and an additional 35 per cent (13,500 hectares) was destroyed in the fire. But about 6000 hectares have been logged since then. The combined impact of fire and logging means that vast swathes of ecologically rich, 70- to 80-year-old ash forest north-east of Melbourne have already been converted to ecologically impoverished, fire-prone forest mostly under 20 years old.

VicForests argues that less than .05 per cent of Victoria's state forests are logged annually, but only a small proportion of available forests are high-value, 70- to 80-year-old ash forests. But it is precisely these forests with their majestic (but not officially "old growth") trees that are being ripped out instead of being left as precious biodiversity refugia and old growth forests of the future. While VicForests claims it has reduced logging statewide by 30 per cent, an expert report commissioned by the Rubicon Forest Protection Group (RFPG, 2016) found that the permitted rate of logging in the Central Forest Management Area (including Toolangi, Marysville and the Rubicon) has doubled since Black Saturday.

Remnant unlogged areas are often fragmented as linear strips alongside roads and streams or buffer zones. Places such as the Royston and Rubicon valleys have been turned into chequer boards of young, plantation-like regeneration trees, or scrubby, weed-infested wasteland in coupes where regeneration has failed.

Eight years ago I saw young eucalypts bursting into crown fire alongside older, taller trees whose leaves were still green the following day. The conversion of mature, biodiverse mountain ash forests into young, dry, single-species forests exacerbates the fire hazard, thereby endangering lives and property. Our marvellous mountain ash forests, containing the world's tallest flowering plants and unique, endangered wildlife, must be allowed to re-grow and flourish in a Great Forest National Park that would attract tourists, modulate climate extremes, protect water catchments, absorb carbon dioxide and slow the spread of fires.

Jill Sanguinetti is a writer and member of the Rubicon Forest Protection Group.