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New research shows alpine grazing does not reduce blazing

The scale and impact, both economic and ecological, of recent bushfire disasters demands a rethink of fire management strategies. A controversial approach receiving more attention internationally is the…

Cattle grazing would do nothing to reduce the impact of alpine fires, such as the 2013 Harrietville blaze. AAP Image/Australian Workers Union

The scale and impact, both economic and ecological, of recent bushfire disasters demands a rethink of fire management strategies. A controversial approach receiving more attention internationally is the use of large grazing animals to reduce fuel loads.

But research we published this week shows cattle grazing does little to reduce Australia’s most destructive bushfires.

There are few specific examples of this management intervention being used in Australia. The exception is cattle grazing in the Victorian High Country, part of the Australian Alps. This has been controversial, pitting pastoralists against environmentalists, and scientists against scientists.

It raises questions about acceptable and unacceptable land uses in national parks. And it raises the issue of Australian cultural heritage, including the perpetuation of an iconic “Man from Snowy River” cultural tradition of summer pasturing of cattle in the Australian Alps.

Proponents of grazing within the Alpine National Park claim “grazing reduces blazing”. The clear public message is that the severe fires seen in Australia’s alpine forests in recent years can be reduced in extent, intensity, and ultimately damaging effects by the continuation of cattle grazing.

But environmentalists point to the degradation cattle cause to alpine ecosystems by spreading weeds, triggering erosion, trampling bogs and fouling streams.

Some scientific studies have shown that there is no link between grazing and reduced fire severity but the generality of these findings has been disputed.

This debate involves an unusual intersection of scientific, environmental, legal and political dimensions. The Victorian Labor Government banned grazing in the Alpine National Park in 2005 because of environmental concerns. When the Coalition came to power in Victoria in 2010, they proposed resolving this issue with a grazing trial of 400 head of cattle per year to investigate hypothesised fire mitigation.

This trial was then blocked by the then Labor Federal Environment Minister on the grounds it would have an unacceptable impact on endangered species under the Environment Protection and Biodiversity Conservation Act.

A Federal Court case brought by the Victorian government subsequently found the Federal Environment Minister acted appropriately. Grazing is still banned within the Park.

In this context, we tried a “natural experiment” to discover whether cattle grazing can reduce blazing. We surveyed over 11,400 km2 of the Victorian Alps by analysing satellite images of the area. We looked at vegetation maps, looked back in time using historical satellite pictures, and took advantage of the cessation of grazing this decade and the extensive area burnt by fires over this period.

To implement our study as a classical experiment - for example by manipulating grazing pressure and imposing experimental fires - would be completely impractical, and prohibitively expensive given the same geographical scale and the risks of application of extensive high-severity fires. It would also be unethical given the potential threats to biodiversity, and under current legislation, unlawful.

We overlaid maps of crown scorch derived from satellite imagery following large bushfires in 2002/03 and 2006/07 with the location of pastoral leases. Crown scorch is a measure of fire intensity, based on the degree to which flames have reached a height which enables them to burn the forest canopy. This crown scorch can be detected in satellite images.

Using geospatial statistics we found that cattle grazing had no effect on the likelihood of crown scorch in eucalypt forests and woodlands.

This result is biologically plausible given that cattle are grazing animals, not browsing animals - they do not extensively feed on woody vegetation focusing on grasses instead. Our study is also consistent with previous ground-based studies that have demonstrated the cattle prefer to graze in grassy areas.

Fires in eucalypt forests are important to study, because to their extreme intensity. Fires in these forests are driven by high fuel loads on the forest floor and dense forest structure. Eucalypt forests have the added capacity for fast-moving fires to occur in the upper canopy, carried by the highly flammable leaves. Such fires are nearly impossible for fire fighters to control.

In comparison, fire intensity in grasslands is much lower, fires are easier to control, and grasslands recover rapidly after fires.

Our study does not rule out the use of cattle to manage grassy fuels – this approach may be crucial in tropical savannas, especially where invasive grasses fuel fires that compromise the ecological integrity of native vegetation.

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11 Comments sorted by

  1. John Newlands

    tree changer

    If hoofed animals are 'unnatural' in parks then so are humans dropping matches from helicopters. The fire frequency must determined by lightning strikes alone. Ditto bulldozed firebreaks and access roads...not natural at all. There's no argument about grazing damage but I don't think we should use that to entirely dismiss grazing as a fuel reduction tool. if the animals were not subsequently sent to the abattoir that might appease some.

    I think that prior grazing can slow a half hearted fire. However an 80 kph 40C flame front seems to be able to leap from treetop to treetop. That makes grass and shrubbery irrelevant. My solution is battery power mulching machines but I doubt they'll catch on.

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  2. Michael McCarthy

    ARC Future Fellow at University of Melbourne

    A summary of the science on effects of grazing in Australia's alps reached the same conclusion as this new research. Cattle grazing does not reduce fire risk: http://www.ecolsoc.org.au/hot-topics/alpine-grazing-does-it-reduce-blazing

    Such a result is not surprising because in alpine areas, fires are driven by woody vegetation not the grass that cattle predominately eat. Alpine grasses are much less flammable than shrubs, etc - this has been demonstrated through correlative studies and by burning experiments. Beyond effects of cattle on vegetation structure (somehow using cattle to replace trees and shrubs by grass, which could only happen over many years by grazing), there is no plausible mechanism by which cattle would reduce fire risk.

    If there is a substantive fire risk in Australian alpine environments, then fuel reduction burning is proven to be effective.

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  3. Wil B

    B.Sc, GDipAppSci, MEnvSc, Environmental Planner

    This argument is coming from false premises. The Victorian government is not at all interested in the science of appropriate fuel reduction in the Australian Alps, they are all about providing privileged access to a small number of families, some of whom happen to be closely related to Ted Bailleau, others that have been Lib or Nat MPs in the past. The only reason they have to pretend that this has anything to do with science is because of the National Parks Act. But all the bureaucrats in the fire division of DEPI know that cattle gazing does nothing, all of the scientists at the Arthur Rylah Institute know that it causes significant damage to ecosystems. This comes very much from the top down, from the Minister's office.

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    1. Henry Verberne

      Once in the fossil fuel industry but now free to speak up

      In reply to Wil B

      I think this is correct and has been my view too. The evidence is clear that grazing has minimal or best ambiguous impact on fires. Self interest and ideology rules.

      Their propaganda is also served by those who display the vacuous slogans on their (usually 4wd's) : "mountain cattle men care for the high country".

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    2. Sebastian Poeckes

      Retired

      In reply to Wil B

      And the whole concept of cattle grazing as a fuel reduction method was dismissed as useless even as far back as the Royal Commission into the Black Friday fires of 1939.

      There's no doubt in my mind that the LNP Government just wants to pay off a few mates with access to almost free forage for their cattle. Anyhow, surely we don't need to put cattle back into the high country to test the concept - we can just examine the effects of the myriad wild horses, goats and deer rampaging around the landscape. (And then shoot them).

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  4. Ian Alexander

    Reader

    Nah, you greenies have got it all wrong.

    If you cut down all the trees, chuck down a bit of super, let plenty of cattle loose and overgraze to buggery there is no chance of bush-fires!

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    1. Alice Kelly
      Alice Kelly is a Friend of The Conversation.

      sole parent

      In reply to Ian Alexander

      Very funny Ian, these are the sort who expect hazard reduction burns will have a great impact also. Despite the fact that if native plants get no rain in winter and spring, most burn really well, and turn into a match themselves. Yes we all know parks are responsible for out-of control fires, and the greens and labour.

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    2. Brett Murphy

      Research Fellow at University of Melbourne

      In reply to Ian Alexander

      Thanks Ian, you are absolutely right that if you really wanted to prevent bushfires you would just chop all the trees down. This mightn’t be so sensible in a national park (where you’d bugger up your park in the process), but might be a realistic option around some population centres. Might lead to less excessive prescribed burning beyond the wildland-urban interface.

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  5. Richard Dunwell

    logged in via email @clear.net.nz

    Hi guys.
    The point of using cattle is not whether to graze or not graze, but to use herd impact to push the carbon down into the soil so it can't catch fire. Have you done this and if so what was your stock density in kg/ha?
    How many disced fire breaks do you have and how wide are they?
    You have a huge amount of carbon sitting there every year.
    You have to put it in the ground or it's going to catch fire.
    Which one do you want?

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