Namadgi National Park is showing good signs of recovery after the worst fires in 60 years and worst drought in a century.
The recovery is showing the classic signs of rejuvenation of a eucalypt forest after fire.
The fire destroys all the leaves and the extremities of smaller branches. This is the active part of the tree which before the fire produced a hormone that prevented buds from sprouting along the trunk and boughs. After the fire the hormone can no longer be produced so the tree sprouts from the trunk and the major boughs. Eventually some of these will dominate and the lesser ones die and the tree will return to its normal look. Any dead branches will fall off.
In some places the fire kills the trees. Here native (and non-native) weed species and smaller plants quickly sprout, using the nutrient ash. So do the seeds of the acacia and large eucalypt species, triggered by the fire. In the absence of larger trees the new trees will grow and crowd out the smaller species so the eucalypt forest eventually returns.
In places where the larger trees survive the fire still triggers the seeds to germinate, but the saplings do not last long as the rejuvenated trees cut out their light.
If there were no periodic fires, it would enable large rainforest species to get a grip and eventually (over centuries or millennium) replace the eucalypts and even generate their own wetter weather patterns.
Despite the drought Booroomba Creek is running. The water is clear, but there is still a fair amount of black soot on the creekbed which looks like it could easily be stirred.
Estimates of the fire damage to Namadgi vary; usually larger the closer to the fire date the estimate was made. It seems that about 90 per cent of the 106,000 hectares was burnt out and there have been huge losses of native wildlife.
But it was burnt out, not destroyed and the recovery is under way.
Dr Murray Evans, senior wildlife ecologist with Environment ACT says he is pleasantly surprised at the bounce-back given the lack of rain.
“The upper water catchment has improved markedly,” he said. “Most of the sediment has been flushed and the new low-level growth has given stability on creek banks.”
In the lower catchment around Bendora the picture is different.
“Sediment is still coming down from the upper areas,” Dr Murray said. “And the fire was more severe so it will take longer for the banks to stabilise.”
On the wildlife side, the number of small ground mammals is lower than immediately after the fire.
“They had a tough winter with their cover and food sources depleted,” Dr Murray said. “But when the habitat comes back the animals will come back.”
Corroboree frogs are still doing better than expected. About 80 per cent of each bog was burnt. The sphagnum moss bogs were vulnerable to drying out and erosion.
Remedial work is being done for both water quality and wildlife.
Dr Murray said, “Fire is a natural occurrence. Usually the bush will bounce back without interference. However, in Namadgi remedial work is especially needed where there has already been human intervention in the form of roads and fire trails.”
He said that in the next five to 10 years we could expect more shrub coverage which would give way when trees began to recover.
Some areas, like the back of the Tidbinbilla Range, would take longer to recover because it had been badly affected. But with rain and time it would recover.
The story is at neither extreme. It is not all destruction, nor is it a magic bounce back as if the fire did not happen.