There is no doubt that our fire seasons are getting longer and more intense and this is starting to have potentially landscape changing impacts. There is concern that Alpine Ash forests could be wiped out in some areas where fire comes in multiple waves before the recovering trees can set seed. Parts of north eastern Victoria have been burnt three times in a decade. Mountain Ash forests face similar threats.
It is tragic that fires are so frequent and intense that we face the prospect of seeing these vegetation communities collapse. There are many ways we must respond: acting decisively on climate change, and protecting these forests from wildfire and over logging. Aerial seeding programs also aim to help these forests survive.
Alpine Ash (Eucalyptus delegatensis) is the classic tree of the sub alpine forests and tends to be replaced by Snow Gum woodlands at higher elevations. In Victoria it is also known as Woolybutt. It only exists in south eastern Australia (there is also a sub species in Tasmania).
In Victoria, it occurs at altitudes between 900 and 1,500 m above sea level.
It is estimated that only 0.47% of remaining old growth Alpine Ash remains in the Central Highlands. It is not clear what percentage of old growth Alpine Ash exists across the state. VicForests states that there is 9,478 hectares remaining of ‘modelled’ old growth Alpine Ash in the east of the state, and that 60% of this is ‘outside the footprint of the 2019/20 fire’ and hence should still be considered old growth (correspondence, 22/3/21). However, we know that ever more frequent fires are pushing the species towards collapse, requiring direct intervention by land managers. According to a research published in a report called ‘Biological responses to the press and pulse of climate trends and extreme events’, alpine ash forests face collapse. The report (from 2018) notes:
‘Since the beginning of the 21st century a series of very large, high severity landscape fires ignited by dry lightning storms have occurred throughout the Australian Alps. These fires have killed swaths of E. delegatensis forest and initiated regeneration. However, large areas of regeneration have been reburnt, in some cases twice, causing population declines or local extinction.
Previous periods of high frequency fires (e.g. fires in 1926 and 1939 at Lake Mountain in Victoria) caused the conversion of E. delegatensis forest to Acacia obliquinervia shrubland. The scale of the current vegetation type conversion appears to be historically unprecedented, driven by recent warming and drying, which is projected to continue with ongoing climate change.’
An increased frequency of extreme events can also lead to population collapse if the population does not have sufficient time to recover before the event recurs. Multiple wildfires in short succession, resulting from increased dangerous fire weather, have resulted in localized conversion of obligate seeder Eucalyptus delegatensis forest to shrubland in the Australian Alps, a process that potentially threatens the entire species’ range’.
The problem is that Alpine Ash need around 20 years to reach reproductive maturity, so if fires happen more frequently than this, local extinction is possible because there is no seed stock to create a new forest.
Other researchers note that during ‘the extensive and severe 2003, 2006/07 and 2009 bushfires in Victoria … about 189 000 ha of ash forest was killed or severely damaged by the three bushfires, which burnt a land area totalling over 2.6 million ha’.
This is not ‘new’ news. For instance, areas within the Harrietville fire boundary in 2013 have been burnt several times over the past decade and Department of Environment and Primary Industries and Parks Victoria ecology experts predict about 2,000 hectares will not be able to naturally regenerate due to the nature of Alpine Ash and its response to fire when it becomes so frequent.
ABOVE: Alpine Ash forest in the Upper Ovens Valley, NE VIC, burnt in the 2013 fires.
And it is the same story with Mountain Ash.
Climate change and extreme fragmentation of habitat is driving Mountain Ash forest in south-eastern Australia towards ‘almost certain collapse in the next 50 years’, according to an assessment by researchers from the ANU.
The key message in this research is:
Researchers “modelled 39 different scenarios and found there was a 92 to 99.99% chance of collapse of the mountain ash forest in Victoria’s Central Highlands by 2067”.
Direct seeding efforts in Victoria
It is clear that we will need to intervene to ensure both these species survive. In some instances this will involve direct seeding. But how does this actually happen? This radio interview, featuring Owen Bassett, of Forest Solutions, which is based in north east Victoria, outlines work being carried out to reseed burnt Ash forests. It originally aired on the Living on Earth program from PRX.
From the story:
“With no intervention, these ravaged forests, located primarily in Southeast Australia, would eventually turn into a different type of ecosystem, like savanna or grassland. Owen Bassett, of Forest Solutions, is not ready to let that happen. For years, he has collected seeds from these trees and manually replanted them in an effort to rebuild the forest”.
“Like Mountain Ash, Alpine Ash are “obligate seeders — that is, they can regenerate after fire only from seed and not from their trunks — “if we have enough seed and we have the means to spread that seed where the forest is going to experience population collapse, then we can intervene, lay seed on the ground, and these forests will return,” Bassett explained. “But it’s easier said than done. We have to collect the seed and we have to distribute the seed, and that’s a mammoth operation.”
He explains how the seed is gathered:
“Bassett has been monitoring the flowering of these species for 26 years. Every year, he maps the distribution of their flowering from a light aircraft, he explained. Once trees have flowered, he marks their location in the landscape. One year later, he can expect these trees will have seed.
At that point, Forest Solutions sends teams of climbers in to scale the 262-foot tall trees and de-limb about a third of the branches on them. “We keep the tree healthy; we keep the growing tip in place,” Bassett said. “We take just a section of that crown out and from that, we can pick the seed pods. They’re sent away and the seeds are extracted from … those pods.”
The seeds are tiny, about the size of coarse pepper, Basset added. “It’s extraordinary to think that such a tall tree, something akin to California redwoods, comes from this tiny piece of cracked pepper-size seed.”
Reseeding requires about a pound per acre, Bassett said. The seed is put in a hopper inside a helicopter and spun out the bottom of the aircraft as it flies. The swathe of seed is only 20 meters wide — about 60 feet”.
He also says that we need government support for these initiatives.
“Bassett has been pressing Australia’s federal government for years to establish a seed bank, but it has only funded small seed collection operations in reaction to fire outbreaks, rather than gather seed steadily and store it away.
“We needed 10 tonnes of seed this year,” Bassett said. That’s the equivalent of about 22,000 pounds of seeds. “At the moment, we might have a third, maybe a half, of that. … It’s very frustrating. But, at this stage, we battle on.”
In May 2020, Forest Fire Management Victoria announced that:
‘Communities in fire affected areas near Walwa and some fire affected parts of East Gippsland may see helicopters flying low over forested areas this weekend and in the coming weeks, as part of a $3 million Mountain and Alpine Ash reseeding project.
Department of Environment, Land, Water and Planning (DELWP) is preparing to reseed nearly 13,000 hectares of public land impacted by the fires. Reseeding works will focus on areas that have been previously burnt by fires in 2003, 2007 and 2014.
Many of these forest areas are not old enough to regenerate naturally, and need this seed collection and sowing project to ensure their survival.
Mountain and Alpine Ash forests are important ecosystems that support a wide range of Victoria’s wildlife and Victoria’s sub-alpine biodiversity’.
The situation is worse after the 2019/20 fire season.
There are extensive stands of alpine ash in the mountains of eastern Victoria, and much of this was burnt. After the fires, one industry rep suggested that “about 10,000 ha of Ash is at imminent population collapse in Victoria”. The company involved in the reseeding efforts noted that it had flown 70,000 ha of impacted Ash to assess the impacts and identify priority areas for reseeding.
This reseeding work continues: In October 2020, it was announced that:
‘The Victorian Government is undertaking the largest forest restoration effort in the state’s history with a $7.7 million operation that airlifted tonnes of eucalypt seeds into areas of forest devastated by last summer’s fires.
Funding from Bushfire Recovery Victoria’s $110 million State Recovery Plan is helping recover thousands of hectares of burnt Mountain and Alpine Ash forest and enabling seed to be collected from healthy bushland to ensure the re-seeding work can be ongoing.
Between May and July more than 4.5 tonnes of eucalypt seed, 3 tonnes of which came from VicForests’ contingency reserves, was spread by helicopter across nearly 11,500 hectares of fire ravaged country, an area the equivalent of about 5,650 MCGs.
The re-seeding focuses on areas of nationally distinctive forests in Gippsland and North East Victoria that also suffered the impacts of fire in 2003, 2007 and 2014, and were severely burned again in the 2019/20 season.
The 2019/20 summer fires severely impacted Alpine Ash forests in both State forests and national parks, creating concern that without action some plant species could be compromised. The BRV funding will also support research to better understand the impact of high severity bushfires to guide future forest restoration efforts.
The project is being delivered by the Department of Environment Land Water and Planning in partnership with VicForests, Parks Victoria, and contractors from regional Victoria’.
In January 2021, Forest Fire Management Victoria reported that ‘Between May and July more than 4.5 tonnes of eucalypt seed was spread across nearly 11,500 hectares of fire ravaged country, an area the equivalent of about 5,650 MCGs.’ This figure covers both mountain ash and alpine ash.
Craig Nitschke is an Associate Professor in Forest and Landscape Dynamics at Melbourne University and has a long connection with forests and fire in the high country.
He says that the reseeding program is essential because of the cumulative impacts of fire on Alpine Ash communities. “Some areas have been burnt up to four times in a short period and the impacts in some areas are absolutely shocking. The Upper Ovens Valley and the Carey State Forest (just north of the Avon Wilderness) and surrounding Alpine National Park areas are priority areas for reseeding, as is almost anywhere along the spine of the Alps where the ash grow.”
The Alpine Ash have been more extensively impacted than the Mountain Ash, which grows predominately to the west. These forests were impacted by the 1926 and 1939 fires, causing a loss of Mountain Ash in places. While it is just a matter of time before it happens again, in recent years the fires have not been as intense in that community. The fires in the Alpine Ash are a mix of light to heavy severity, with the impacts greater in the heavily burnt areas. But even across the burnt regions, a mosaic of forests burnt at different severities has been created. It is worth noting that in some areas the Ash are persisting without intervention. Even tripled burned areas can sometimes retain young regrowth and have new seedlings. However, other areas are transitioning into something else. “It likely will not be the same type of forest that it was before the fires”.
Craig feels that the reseeding program is a good one and seed availability and ability to distribute it in affected forests should be able to keep up with the need to regrow severely affected forests for the moment. However, he is concerned that if fires continue to occur more frequently this balance will be lost in the future.
In the Snow Gum forests, researchers are seeing more mortality after three fires. Fire affected forests where the canopy survives tend to be more open, with the understory community affected after multiple fires with more grass present, and fewer shrubs. Snow Gums at higher elevations seem to be more susceptible to mortality after fire. Craig reminds us to look beyond the trees: “It’s the understory where much of the biodiversity is”.
“We probably don’t know enough yet about the impacts of fire on woodlands at higher elevations”. Fire may help rejuvenate the seedbank but multiple fires or severe fire may change the seedbank composition and hence influence what trees and shrubs come back after fire.
And as trees in the Snow Gum woodlands start to collapse after earlier fires, it is not yet clear what impact this might have on future tree growth and forest health. On one hand, having lots of logs on the ground means it may burn hot in the case of a fire. But log tangles can create micro sites that may provide sheltered habitat for seedlings or protect them from browsing.
Having repeated fires tends to push forests towards heterogeneity. Yet within these burnt landscapes there is still huge diversity in the age and structure of forests due to the patchy nature of how wildfire tends to burn. In many areas the Alpine Ash will recover if the frequency of fire can be controlled. But in other areas, intervention through reseeding is necessary to see the Alpine Ash communities continue to thrive.