On Jan 13th 2016, approximately 70 lightning strikes hit the west of Tasmania.
About 20 of those strikes started fires.
So many lightning strikes. There were more than usual. However, fire caused by dry lightning in this area is totally expected. What was not expected is the devastation that followed.
The great dry
Fires in Tasmanian alpine areas are bad for flora and fauna. Unlike many other Australian vegetation types, rainforest, confer forest and peatland vegetation are not adapted to fire. They are also not adapted to being dry. For the past 16 years the west of Tasmania—usually known for being wild, wet and windy—has been in a state of record low rainfall, in other words, drought.
Images of the Gordon River Dam, operating at an all-time low of 6.7% are sending ripples through the community – click here and here for images comparing water levels and click here for a video of Lake Gordon and surrounds currently.
The Bureau of Meteorology’s website states ‘Research suggests that long-term drying trends over southern Australia cannot be explained by natural variability alone’. Long-term processes, such as drying out of forest fuels, are most significantly affected. While in the past month soil moisture may have shown significant change for the better for some parts of Australia, it’s not so for western Tasmania where very much below average soil moisture levels remain.
The last substantial fires that decimated pencil pine, in the spring-summer of 1960–61 were during a very dry period. In fact it was the driest spring-summer on record from the 1930s to present (Holz et al. 2015). That is, it WAS the driest until the spring-summer of 2015-2016. The figure below is from automatic weather station rainfall data collected at Butlers Gorge, Tasmania. Note the recent spring-summer rainfall – 404 mm. The rainfall data from 1960-1961 spring-summer was 524 mm. The landscape so accustomed to being wet and lush is dry and crisp.
A once lush and wet landscape is now crying dry tears
Most of western Tasmania is listed as a World Heritage Area due to its natural values. Within this is the Central Plateau, a mosaic of high altitude mountain peaks and alpine tarns, surrounded by alpine heath and scrub, rainforest, conifer forest and peatlands. The outlying edges off the plateau extend to lower altitude forest dominated by towering eucalypts and an understorey of broad and narrow leaf shrubs. Whilst the low-lying vegetation, alpine heath and alpine scrub are amenable to drying and fire, the rainforest, conifer forest and peatland vegetation are not.
At the upper altitudes, relict Gondwanan species hang on. Athrotaxis cupressoides, otherwise known as Pencil Pine, is a Tasmanian endemic evergreen tree (or shrub) which can grow up to 10–20 m tall. Some trunk diameters have been recorded at 1.0–1.5 m. It mostly occurs in the high elevation (700–1300 m asl) areas in alpine and sub-alpine vegetation, mostly near the Central Plateau; it has also been recorded in rainforest but being shade intolerant it prefers canopy gaps. The species is long lived—over 1,000 years. The production of wind-dispersed seeds doesn’t begin until a tree is about 2 m tall and then it is episodic; heavy seeding can occur at 5–6 year intervals. Mast seeding for A. cupressoides and its relative A. selaginoides is synchronous; seeds mature and are released (as cones) between April and May and cones are not serotinous^. In 2015 there was a major masting of four of Tasmania’s alpine conifers–A. cupressoides was one of the four captured in a seed bank collection opportunity. Although fire sensitive, vegetative growth can occur via root suckering (Cullen and Kirkpatrick 1988).
Pencil Pine is listed as Vulnerable on the IUCN Red List of Threatened Species, and is present in three threatened native vegetation communities listed under Schedule 3A of the Nature Conservation Act 2002, with the main cause of its decline due to bushfire–the main area of its range was affected by the fires of 1960–61. These fires started in October 1960, with many extending until February 1961 (whilst the above ground fire may be out, peatlands may continue to burn underground, which in turn may kill the roots of pencil pine–see more below). The 1960–61 fire, which burnt in excess of 30,000 ha, has been described as one of ‘the most ecologically significant fires to be recorded throughout Australian history’. The fire consumed vast areas of the Central Plateau where vegetation communities not adapted to fire, such as areas of deciduous beech, conifer vegetation and peatland, were wiped out. It is estimated that the 1960–61 fire resulted in a loss of 30% of the range of A. cupressoides and A. selaginoides; a severe loss in range compared to what it once was as a consequence of uncontrolled fires since 1802 (Brown, 1988).
The World Heritage Area hasn’t seen destructive fire since the 1930s and 1960s events. Even the January 2016 fires don’t come close to darkening the devastation that has occurred previously. The 1930s fires are only eclipsed by the 1890s fires; the latter are estimated to have burnt 1,000,000 ha of the state, predominantly in the south. Although also predominantly in the south, the 1930s fires, particularly the 1933–34 event, did venture to the Central Plateau but fire boundaries are sketchy. It is estimated that fire was present around the Walls of Jerusalem National Park (in particular Lake Bill, Lake Louisa, Lake Myrtle, Lake Adelaide (Johnson & Marsden Smedley 2002).
We have a good indication of where the 1960-61 fires were (Corbett 1995). There is strong evidence that the 1960-61 fires were deliberately lit by highland graziers. As was the practice of the time, the promotion of ‘green-pick’ was enabled by setting fire to the thick vegetation. Ironically, the fires that were lit in 1960–61 were outside areas approved for grazing (Johnson & Marsden Smedley 2002).
In 1960–61 sixty percent of the Central Plateau area burnt, including over 30% of the extent of Pencil Pine woodlands. You see the stands using Google Earth, that’s how visible the dead trees are. We know that no seeding event occurred before the 1960–61 fire, limiting recruitment. We also know that these young seedlings were browsed by introduced and native herbivores, hindering the growth of some stands. However, we know that not all the fire was of high intensity and vegetative sprouting did occur and that not all seedlings were browsed out; current mapping of dead pencil pine has patches of dead stags with a few live pencil pines present. Since this time, the number of unauthorised ignitions has significantly reduced.
Evidence from the past fuels direction for the future
The recent 2016 fires were not as catastrophic for pencil pine compared to the fires of 1960–61. In 2016, very little (close to 1-2%) of the known distribution of pencil pine was burnt.
The fires were preceded by a seeding event, and forethought means collected seeds may assist in regeneration. However, the pencil pines appear to mostly be spreading vegetatively. This information is significant for three reasons:
- pencil pines are possibly much older than previously thought,
- if clonal stands are predominant, why are the not recruiting from seed? Low in situ seed recruitment may have big implications for future restoration,
- clonal stands mean lower genetic diversity, so the resilience of the species to adapt to disturbance (disease, climate change, stochastic risk [fire]) is decreased.
In the absence of fire, fuels accumulate and aged, especially in fire dependent vegetation such as button grass moorlands and lowland wet eucalypt forests. These areas are now large, and coupled with this increased flammability is wider variation in fire weather and behaviour, partly driven by a changing climate. Burning of fire sensitive vegetation burning is an increased possibility.
This landscape can never be replaced
In Tasmania we have a fully integrated fire response system. We have mapping of fire sensitive vegetation. This mapping needs updating and I’m working with Prof. David Bowman’s group to improve what we know about the ecology and distribution of pencil pine, for both living and dead stands, in Tasmania. Our response to fire is informed, direct and efficient, but it needs constant vigilance and updating by experts.
Those with expertise in fire behaviour and management (ecologists, conservationists, fire managers) recognise that these 2016 fires threatened something unique to Tasmania: pencil pine, cushion plants, and cool temperate rainforests. Pencil pine grows on non-organic (mineral) substrates and also well drained, organic areas, such as peatland. These organic soils are ancient and valuable to pencil pine; they take eons to replace. The burning of peatland means the substrate to facilitate recruitment* and the underground storage of seeds and tissues are both killed, with no regeneration possible (root suckering is a means of regeneration for pencil pine).
Pencil Pine is sensitive to moderate to high intensity fires and has been obliterated from areas with little refuge from fire. Being pushed to the brink could be the reason why pencil pine hugs tarns and shelters under cliffs; safe havens from the conflagrations creeping up from lower elevations below. The reason it loves growing in these areas could be because it’s being pushed there as a result of fire and climate. Now, with a changing climate even these refuges are drier than usual. And that makes them more likely to burn. Where has the Pencil Pine left to hide? The suggestion of moving species to botanical gardens, or in the worst case, the subantarctic, is not as far-fetched as it sounds.
A non-ecologist friend asked me what was going to be left for our children. Between us we have eight children aged between 4 and 11 years old. Whilst she applauded that human life was protected first, she questioned how we could not value the environment with the same regard? What environmental legacy will we leave for our children? Quite frankly, what will be left for our children to see? To describe what we see today, I refer you to an article written by Prof. Jamie Kirkpatrick detailing his early experiences with the wilderness landscape that is the Central Plateau and his subsequent revisit to that area (click here for a .pdf or here for html or the whole text of ‘Celebrating Wilderness’ is here). A revisit is what I one day hope for myself and my children. The chance of full recovery of these pencil pine stands in our lifetimes is impossible. It will NEVER happen. The species is unlikely to attain the original extent of its distribution within the next several thousand years. Resurrecting the alpine flora to its pre-fire glory for our children is non-existent. Whilst I value most the lives of my family, I value the protection of ancient landscapes too.
We need better mapping to direct fire management (where to focus resources). I know, because in January I was mapping the distribution of the pencil pine as it burnt. We need more people trained to deliver remote-fire response. Because of the remoteness and incidence of dry lightning strikes in western Tasmania, fire management will always be challenged. We need more support to the ecological staff in conservation management – they need more experts employed to update fire-sensitive vegetation mapping (like pencil pines), and to provide, administer and update conservation management advice.
I certainly hope politicians rise to the occasion and change the current situation before the unique alpine landscape that the Tasmanian public treasure is threatened by fire again.
Thanks to Sam Wood and Andrés Holz for their comments and insight. Thanks also to Rob Blakers and Sam Wood for images and maps.
^serotiny = where seeds require an environmental trigger, like heat or fire, to cause release rather than instantaneously when mature
*The synchronous episodic seeding, and lack of serotiny, limit recruitment.