Wildfire in Rye, St Andrews Beach & Blairgowrie
Weed-free Coastal Alkaline Scrub
Some facts about these vegetation types and fire
Article by Wonga
These areas are included in the extreme fire danger category in the post Royal Commission Victorian Fire Risk Register, while Arthurs Seat (with a long and colourful fire history) is not. It's stated that this listing isn't due to a scientific rating of extreme inherent flammability of this bushland type or the presence of any recent fire history (research has indicated that last known wildfire of any size was in January 1910)
This part of the Mornington Peninsula on the list because of the high numbers of holiday-makers in short term rentals that have no fire plan with little sense of the need for one and the lack of exit routes, a legacy of the poorly planned ad hoc sub-division in the past and the narrow linear geography of the peninsula
Short of cutting down all the Tea-tree, which isn't going to happen, the question is how to reduce the fire danger without losing the character or any more habitat and biodiversity?
Understanding the vegetation, it's structure and dynamics and the processes acting on it, is the key to planning for fire protection and risk mitigation management
Present condition
Much of it is in a state/stage of long-term natural regeneration succession, following it's historical, industrial scale disturbance (cattle, sheep, loss of all the originally dominant Drooping Sheoaks for lime burning and the Wirilda wattle for bark and firewood, harvesting of tea-tree and Moonah fire Melbourne's bakers ovens, clearing, environmental weeds, rabbits etc)
On the higher rises (the old dunes) of the Nepean Peninsula, Coastal Moonah Woodland (an FFG listed component of Coastal alkaline scrub - EVC 858) still dominates and, when not weed-invaded, has been has been shown to be a non fire-prone vegetation type See this page for references. This vegetation type is restricted in Victoria to only a few locations on old alkaline dunes
The lower flat areas once supported a open grassy understory with scattered Banksias, Sheoak and Wattle.This vegetation type (Calcareous Swale Grassland EVC 309) is yet to be fully mapped or described for the Nepean Peninsula.
A good deal of the vegetation type in question, currently has a canopy of Coast Tea-tree, which mainly colonised the lower areas (see above) or the ridge lines the wind tolerant Sheoak and Moonah once dominated. This species (Tea-tree) only colonises bare sand or sand exposed by fire (particularly after Autumn burns). It is relatively short lived and is declining in many areas of the Peninsula. It is however an important successional phase in the development of Coastal Alkaline Scrub when left undisturbed.
Much public and private land has the waxy, flammable Sweet Pittosporum and the shrub Polygala or Myrtle-leaf Milk-wort, often in thicket proportions, as an upper and lower middle-story. All are dangerous, highly flammable in summer and completely alter and eventually dominate the naturally open vegetation structure
Add thick, weedy summer dry grasses and the fuel loads increase dramatically...
Article by Wonga
These areas are included in the extreme fire danger category in the post Royal Commission Victorian Fire Risk Register, while Arthurs Seat (with a long and colourful fire history) is not. It's stated that this listing isn't due to a scientific rating of extreme inherent flammability of this bushland type or the presence of any recent fire history (research has indicated that last known wildfire of any size was in January 1910)
This part of the Mornington Peninsula on the list because of the high numbers of holiday-makers in short term rentals that have no fire plan with little sense of the need for one and the lack of exit routes, a legacy of the poorly planned ad hoc sub-division in the past and the narrow linear geography of the peninsula
Short of cutting down all the Tea-tree, which isn't going to happen, the question is how to reduce the fire danger without losing the character or any more habitat and biodiversity?
Understanding the vegetation, it's structure and dynamics and the processes acting on it, is the key to planning for fire protection and risk mitigation management
Present condition
Much of it is in a state/stage of long-term natural regeneration succession, following it's historical, industrial scale disturbance (cattle, sheep, loss of all the originally dominant Drooping Sheoaks for lime burning and the Wirilda wattle for bark and firewood, harvesting of tea-tree and Moonah fire Melbourne's bakers ovens, clearing, environmental weeds, rabbits etc)
On the higher rises (the old dunes) of the Nepean Peninsula, Coastal Moonah Woodland (an FFG listed component of Coastal alkaline scrub - EVC 858) still dominates and, when not weed-invaded, has been has been shown to be a non fire-prone vegetation type See this page for references. This vegetation type is restricted in Victoria to only a few locations on old alkaline dunes
The lower flat areas once supported a open grassy understory with scattered Banksias, Sheoak and Wattle.This vegetation type (Calcareous Swale Grassland EVC 309) is yet to be fully mapped or described for the Nepean Peninsula.
A good deal of the vegetation type in question, currently has a canopy of Coast Tea-tree, which mainly colonised the lower areas (see above) or the ridge lines the wind tolerant Sheoak and Moonah once dominated. This species (Tea-tree) only colonises bare sand or sand exposed by fire (particularly after Autumn burns). It is relatively short lived and is declining in many areas of the Peninsula. It is however an important successional phase in the development of Coastal Alkaline Scrub when left undisturbed.
Much public and private land has the waxy, flammable Sweet Pittosporum and the shrub Polygala or Myrtle-leaf Milk-wort, often in thicket proportions, as an upper and lower middle-story. All are dangerous, highly flammable in summer and completely alter and eventually dominate the naturally open vegetation structure
Add thick, weedy summer dry grasses and the fuel loads increase dramatically...
The natural state
It should also be understood that the natural, weed-free structure of the Nepean Peninsula vegetation communities is one of a sparse ground cover by perennial and annual herbs that have disappeared by summer and scattered native grasses that are small and actively growing (green) in summer with a sparse open mid story. This is a mossy low woodland with a substantial cover of climbing, scrambling and creeping, genuinely flame-retardant indigenous succulents e.g. Bower Spinach and Sea-berry Saltbush
Many of the native mid-story, Coast Beard Heath, Olearia and Correa etc.in these woodlands have a comparatively low flammability
The grassy bowls with scattered trees and summer green native grasses are also less flammable than summer-dry pasture. In Summer an offshore fog rolls in most afternoons and in Winter the low lying bowls act as cold air drainage lines. Frosts are not uncommon. The vegetation is adapted to collecting and holding this moisture and the heavier terra rosa soils aid in this water holding capacity.
In many areas cohorts of disturbance-generated Coast Tea-tree are now scenescing (dying) and not being replaced by seedlings, as their part of the successional process is done. The next stage will then develop as the understory trees and shrubs grow and regenerate to become the canopy of a more open, older vegetation
If the sandy ground is then disturbed by clearing of the ground story or burnt at an inappropriate time (autumn) a new cohort of Coast Tea-tree will rise from the soil store of seeds and the Tea-tree primary colonisation cycle (of many decades duration) will begin again That is the Tea-tree's niche in the world.
Many of the native mid-story, Coast Beard Heath, Olearia and Correa etc.in these woodlands have a comparatively low flammability
The grassy bowls with scattered trees and summer green native grasses are also less flammable than summer-dry pasture. In Summer an offshore fog rolls in most afternoons and in Winter the low lying bowls act as cold air drainage lines. Frosts are not uncommon. The vegetation is adapted to collecting and holding this moisture and the heavier terra rosa soils aid in this water holding capacity.
In many areas cohorts of disturbance-generated Coast Tea-tree are now scenescing (dying) and not being replaced by seedlings, as their part of the successional process is done. The next stage will then develop as the understory trees and shrubs grow and regenerate to become the canopy of a more open, older vegetation
If the sandy ground is then disturbed by clearing of the ground story or burnt at an inappropriate time (autumn) a new cohort of Coast Tea-tree will rise from the soil store of seeds and the Tea-tree primary colonisation cycle (of many decades duration) will begin again That is the Tea-tree's niche in the world.
Below: Nepean Peninsula Tea-tree scrub with a natural cover of indigenous fire-retardant Bower Spinach, Seaberry Saltbush with Small-leaf Clematis. Many residents (and some authorities) slash, spray and otherwise remove this natural fire protection (sometimes on the subjective grounds that it is "taking over") and the natural replacement is almost always flammable weeds
These species are easily propagated and are available in indigenous nurseries. Bower Spinach Tetragonia implexicoma can be easily spread by planting sections of existing plants as runners
These species are easily propagated and are available in indigenous nurseries. Bower Spinach Tetragonia implexicoma can be easily spread by planting sections of existing plants as runners
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Weedy grasses are Highly Flammable
Wild Oats on a roadside
Introduced grasses can produce many times the fuel load and burn at many times the intensity of native grasses. One common invasive species, Phalaris has ten times the summer fuel load as the wallaby, spear and kangaroo grasses that naturally occur in weed-free Nepean bushland
Annual grasses are dead in summer and are dry and highly flammable, while some perennial weedy grasses are dormant and carry much dry mass in summer
All annual grasses on the Mornington Peninsula are summer-dry fire-hazardous weeds
Why are introduced perennial grasses considered a threat?
Annual grasses are dead in summer and are dry and highly flammable, while some perennial weedy grasses are dormant and carry much dry mass in summer
All annual grasses on the Mornington Peninsula are summer-dry fire-hazardous weeds
Why are introduced perennial grasses considered a threat?
Woody weeds are also Highly Flammable
Point Nepean, Woody weeds, Polygala in an otherwise open Moonah Woodland
The main woody weeds in this landscape are Sweet Pittosporum, Polygala or Myrtle-leaf Milkwort, Sydney Sallow Wattle, African Boxthorn and Italian Buckthorn
These plants introduce false middle and understory density and substantially increase fuel loads
Other considerations
A lack of loose ribbony bark and the small leaves of the dominant canopy species of Moonah, Coast Wirilda (a rare wattle), Drooping Sheoak, Coast Tea-tree, Sweet Bursaria and Coast Beard Heath means there's not much chance of "spotting" ahead of a fire by large flying embers and a much lesser chance of intense ember attack than in most Australian bushland types
The lack of wildfire experience and thus knowledge in this vegetation type may be contributing to possibly faulty perceptions about it's actual flammability in a non-weedy state. It's worth noting that the recent burns in the Point Nepean unexploded ordinance sites, the vegetation needed to be flattened by a large machine and left for some months to dry out so that it could be fired and would keep burning...
That said, given that extreme fire events are forecast to occur more often and that it's probably a case of when and not if for a wild fire, reducing the possible intensity and severity is possibly the only realistic goal and given that on Black Saturday, anything catching fire, including a roadside, paddock or a house would have burned fiercely and the fire would have rapidly spread in a southerly direction
The narrow nature of the peninsula at this point means that a fire with a hot northerly behind it, will only travel a couple of kilometres at most, with a narrow front, before it runs out of scrub to burn. The fear is that a wind change to the west and then south-west could push the flanks or a fire east along the Nepean Peninsula. Sensitive weed control along major north-south roads such as Canterbury Jetty Rd would be an efficient use of resources
Unhelpful press releases by some authorities has created confusion and amped up fear levels with residents being told beaches are not a safe place ("a death-trap") stating that Tea-tree dominated scrub goes all the way to the beach. This is not the case on the ocean beaches and on many Westernport beaches
Amplified fire hazards
In extreme weather conditions most native vegetation represents a wildfire hazard to some degree, but the majority of the actual fuel load in this area is in the ground and middle story plants, which, in much of this scrub, is weeds, both woody and grassy
A lack of loose ribbony bark and the small leaves of the dominant canopy species of Moonah, Coast Wirilda (a rare wattle), Drooping Sheoak, Coast Tea-tree, Sweet Bursaria and Coast Beard Heath means there's not much chance of "spotting" ahead of a fire by large flying embers and a much lesser chance of intense ember attack than in most Australian bushland types
The lack of wildfire experience and thus knowledge in this vegetation type may be contributing to possibly faulty perceptions about it's actual flammability in a non-weedy state. It's worth noting that the recent burns in the Point Nepean unexploded ordinance sites, the vegetation needed to be flattened by a large machine and left for some months to dry out so that it could be fired and would keep burning...
That said, given that extreme fire events are forecast to occur more often and that it's probably a case of when and not if for a wild fire, reducing the possible intensity and severity is possibly the only realistic goal and given that on Black Saturday, anything catching fire, including a roadside, paddock or a house would have burned fiercely and the fire would have rapidly spread in a southerly direction
The narrow nature of the peninsula at this point means that a fire with a hot northerly behind it, will only travel a couple of kilometres at most, with a narrow front, before it runs out of scrub to burn. The fear is that a wind change to the west and then south-west could push the flanks or a fire east along the Nepean Peninsula. Sensitive weed control along major north-south roads such as Canterbury Jetty Rd would be an efficient use of resources
Unhelpful press releases by some authorities has created confusion and amped up fear levels with residents being told beaches are not a safe place ("a death-trap") stating that Tea-tree dominated scrub goes all the way to the beach. This is not the case on the ocean beaches and on many Westernport beaches
Amplified fire hazards
In extreme weather conditions most native vegetation represents a wildfire hazard to some degree, but the majority of the actual fuel load in this area is in the ground and middle story plants, which, in much of this scrub, is weeds, both woody and grassy
Fire-breaks
Phalaris aquatica invading a recently constructed "firebreak" on a Rye reserve
Fire is an emotive issue and perceptions are powerful. Public fear, whether justified or not, is the big driver of pressure to clear the bush or create "firebreaks" on public land and land managers often respond with a cleared strip around the edge of the bush. There is no dispute (see the various fire royal commissions) that in a wildfire, fire-breaks have no effect in arresting the spread of a wildfire
Fire-breaks (usually 5 metres wide in Nepean shire reserves) are misnamed and while going some way to appease fearful neighbors, they merely function as access tracks and control lines for possible controlled burns and also have an edge effect where the adjacent vegetation is degraded and in total, new breaks represent a significant loss of habitat, biodiversity and connectivity
Disturbance of any kind in bushland, particularly to the ground layer, results in weed invasion Invasive weeds are often the most successful primary colonisers of disturbed ground
That's why they're called invasive weeds
Usually, the fire break itself is immediately invaded by summer dry, high fuel load, grassy and other weeds (see Phalaris on a break above) and may become a greater fire danger than the bushland that was cleared to build the break
The cleared strips then consumes already sparse shire bushland management resources that could have been used to remove 100% of the flammable weed loads in the reserve and having a genuine effect on the intensity and spread rate of a fire. Since the 2009 fires, the shire has had to create kilometres of new "fire-breaks" around reserve edges that now need to be managed
Pressure for works to clear narrow firebreak strips along the National Park boundary on the ocean coast is destructive, impractical and next to useless, given the fact the wildfires will always come from the other direction. Parks Victoria, to their credit, have been instead concentrating on reducing fuel loads beside the many access roads to the beach, by removing flammable woody and other weeds and simply reducing the height and mass of the indigenous road side shrubberys by pruning
Fire-breaks (usually 5 metres wide in Nepean shire reserves) are misnamed and while going some way to appease fearful neighbors, they merely function as access tracks and control lines for possible controlled burns and also have an edge effect where the adjacent vegetation is degraded and in total, new breaks represent a significant loss of habitat, biodiversity and connectivity
Disturbance of any kind in bushland, particularly to the ground layer, results in weed invasion Invasive weeds are often the most successful primary colonisers of disturbed ground
That's why they're called invasive weeds
Usually, the fire break itself is immediately invaded by summer dry, high fuel load, grassy and other weeds (see Phalaris on a break above) and may become a greater fire danger than the bushland that was cleared to build the break
The cleared strips then consumes already sparse shire bushland management resources that could have been used to remove 100% of the flammable weed loads in the reserve and having a genuine effect on the intensity and spread rate of a fire. Since the 2009 fires, the shire has had to create kilometres of new "fire-breaks" around reserve edges that now need to be managed
Pressure for works to clear narrow firebreak strips along the National Park boundary on the ocean coast is destructive, impractical and next to useless, given the fact the wildfires will always come from the other direction. Parks Victoria, to their credit, have been instead concentrating on reducing fuel loads beside the many access roads to the beach, by removing flammable woody and other weeds and simply reducing the height and mass of the indigenous road side shrubberys by pruning
Conclusion
The control/elimination of flammable environmental weeds from Nepean Peninsula bushland, both on public and private land, is by far the most effective management technique available to authorities and landholders to reduce wildfire ignition likelihood, spread, intensity and severity
This is the only realistic and practical bushland management action that will actually have a substantial and lasting effect on the safety of residents and summer visitors
See this page for references used in this article
