Forestry Corporation has embarked on a seed collection program to safeguard some of the most iconic forests in New South Wales. The giant eucalypt forests of the NSW high country dominated by Alpine Ash were severely impacted by the Black Summer bushfires. Source: Timberbiz
The species, despite its enormous dimensions is highly susceptible to fire and large tracts of mature trees died in more than half of the species’ distributions across the forest estate.
A similar outcome was also recorded for the species White Ash, which occurs in tableland and coastal forests of southern NSW.
Alpine Ash (Eucalyptus delegatensis), growing up to 70-metres in height, and White Ash (Eucalyptus fraxinoides), growing up to 40-metres, are ‘obligate seeders’ meaning the trees die after exposure to fire, even where the fires are not hot or intense.
The species regenerate solely on seeds stored in soil or the tree canopy.
This means after a single fire, ash trees can regenerate in large numbers, however, the regenerating forest is vulnerable to future fires until it has matured to develop seed itself, which occurs after 20 years.
Forestry Corporation’s Southern Resources Supervisor Joel Dawson said there is now a risk that future wildfires could impact both species’ survival.
“Having a seed bank for these species will be crucial in the event of another fire. This is why it is so important that Forestry Corporation builds an insurance seed store,” Mr Dawson said.
“The collection of Alpine Ash seed has centred around Bago and Maragle state forests near Tumbarumba as these populations are most of risk of repeat fires,” he said.
To ensure these species will continue to inhabit our forests a seed program was initiated, which identifies where mature trees in the forest are carrying seed and flowering.
“We have had staff conducting surveys of flowering for a couple of years now and we are expecting good seed crops in the coming years based on those surveys,” Mr Dawson said.
Forestry Corporation has contracted trained arborists who specialise in seed collection and extraction to scale the ash trees and prune seed pods from the canopy.
“We collect from healthy trees through a light pruning of about 30-50% of the canopy. It’s a one-time collection operation from each tree and then we record their location and exclude them from future seed collection programs,” Mr Dawson said.
“We need to preserve these important species from not just fires, but also pests and weeds that threaten the health of the forest.
“We will also look to use these seed stores to actively regenerate areas where we identify poor regeneration following the 2019/2020 bushfires.”
So far this year, White Ash seed collection has occurred on the Far South Coast and Alpine Ash seed collection has been completed in Maragle State Forest.
“We have monitored the forests over the past few years to pinpoint the flowering events and found and harvested these seeds collecting 25-kilograms of white ash seed to restore the stock,” Mr Dawson said.
The seeds are extracted from pods through a drying process in a rotary kiln and then stored in a cool room at Eden.
“It’s an extensive process where nearly a tonne of seed pods produces about 25 kilograms of seed, which is just enough to fill three buckets,” Mr Dawson said.
“Eucalypt seeds are very small, and despite the massive size of the mature trees an Alpine Ash seed is only 2-3mm in size once extracted,” he said.
After the 2019/2020 bushfires some harvesting occurred in the burnt Ash forests, which allowed some of the dead timber to be utilised before it degraded, but that harvesting has now finished.
Regeneration surveys following the fires are being conducted by drones to determine if any additional rehabilitation and seed sowing might be required to regenerate the forest.
Find out more about Forestry Corporation at www.forestrycorporation.com.au
