I think the situation is a lot more complicated.
The obvious one is that in the Australian situation, controlled burns
are intended to reduce the frequency and extent of major out of control
fires. The controlled burns tend to be of lower temperature and
hopefully confined to the combustion of small dried branches, grass etc.
which is likely to be recycled back into CO2 fairly quickly anyway by
bacteria, fungi etc. Most of the large trees containing a large
proportion of the carbon shouldn't be significantly affected. Most out
of control fires release a much higher proportion of the sequestered
carbon as they can burn up even large trees.
So I would suggest that in the medium to long term the use of controlled
burns could increase the average amount of sequestered carbon.
This isn't the case in places like Indonesia where the purpose of the
fires is to remove all the vegetation permanently so that the land can
be used for agricultural purposes.
A second factor is how carbon is sequestered. Most accounts refer to
sequestration of carbon in the form of 'organic' carbon. That is carbon
in organic molecules; in trees, in other vegetation and in the soil.
Unfortunately all such 'organic' carbon can and will be relatively
easily metabolized. That is, virtually every carbon atom in most trees
and other vegetation as well as 'organic' carbon in the soil is liable
to be recycled over some relatively short period of time. So a mature
forest is probably close to equilibrium in terms of the degree of carbon
sequestration in vegetable matter.
However in the case of fire, particularly in low intensity fires, a
significant proportion of the vegetation, is converted to charcoal. In
general this elemental carbon cannot be metabolized by organisms. The
only way that this can be remobilized is by oxidation (fire) or other
chemical means. This matter is likely to get mixed into the soil column
where its turnover time would be very long, and could contribute
significantly to the amount of sequestered carbon in natural areas,
although at an admittedly rather slow rate.
In this case fire is required to divert carbon into this long lived
store. So controlled fires could be a factor in allowing even
relatively mature forests to continue to accumulate carbon.
In fact there have been serious suggestions that wholesale conversion of
trees or other organic matter into charcoal and then burial would be one
way of removing significant amounts of carbon from the atmosphere.
Cheers
Andrew
Evan Beaver wrote:
Thanks a lot Chris, Rob and Andrew, I knew I could get some reasoned
debate from the birders.
The argument being presented (this was on Crikey, Tuesday, included
below) was that hazard reduction burns should be included in
Australia's Greenhouse Accounting. I think this is madness, for the
reasons stated in the quote which the author is trying to suggest is
some sort of conspiracy.
Accounting CO2 released in burns would definitely lead to 'perverse
outcomes'. My facetious example is that home owners whose house has
burnt to the ground will be handed a bill for the CO2 emitted during
the fire. More likely though, is consternation among fire
brigades/land managers about the balance between CO2 and hazard
reduction. It's just another variable, poorly defined, to throw on top
of the management problem we already have.
>From a CO2 accounting perspective it's a bit of a silly argument too.
The current guidelines state that some CO2 will be released by fires,
but some will also be taken up somewhere else at the same time. Seems
reasonable, if not a little vague. But then the problem comes from, if
you're going to count intentional burns, are we going to add 'wild'
bushfires? What about wood heaters? Volcanic eruptions? All of these
things emit carbon, but it is short term and 'mostly' part of the
natural cycle. Much better to concentrate on our intentional emissions
first. Further, are we going to deduct the methane that could have
been released had the plant matter rotted anaerobically? Or the CO2
for aerobic rotting? Madness, but expect more of it in the next few
months.
One last thing. Did anyone see '2 In The Top End' when they were
looking at Gouldian Finch burns in the north? Very interesting
discussion on the pros and cons. It's no longer available on line
though.
EB
Fuel reduction burns not included in Australia's C02 accounting
Crikey naturalist Lionel Elmore writes:
This spring and the coming autumn will see a three fold increase in
Victorian fuel reduction burns, which has a huge impact on Australia's
carbon emissions.
Nearly 400,000 hectares will be torched this year, and at emissions of
30 to 300 tonnes of CO2 (or more) per hectare, the CO2 emissions from
these alone may be from 12 to 120 million tonnes a year. That's more
than 10% of Australia's total emissions. This burning includes
so-called ecological burns in Victoria which are planned for many
National Parks and are supported by botanists.
The forest industry, however, does not include these emissions when
tallying its contribution to sequestering carbon, which it claims
amounts to 23 million tonnes of CO2 pa!
In the view of the International Panel for Climate Change and the
Australian Greenhouse Office, the CO2 from fires is simply
"reabsorbed" when the bush regrows. But common sense dictates that the
interruption to carbon storage by fire leaves a sequestration deficit
even if the bush recovers its storage capacity after each fire. The
CO2 that would have been absorbed annually if the fire had not been
lit is effectively an ongoing emission.
There are concerns in Victoria regarding the amount of burning and the
disregard for the CO2 it produces. An email distributed by
conservationists from Gippsland sought comment from botanists,
environmentalists and others on the position of the Federal Department
of Climate Change. In part, the email stated:
Carbon dioxide emissions from fires
Carbon dioxide emissions are not reported for the burning of forests
or savannas under the UNFCCC or Kyoto Protocol accounting frameworks.
Currently, by international agreement, we assume that, for the entire
Australian forest and savanna estates, the carbon dioxide emissions
released from fires are offset by the carbon sink effects from the
regeneration of forests and savannas from previous fires over the long
term. In other words, while the emissions from any one bushfire event
may be substantial, the net effect of fire events across the entire
forest area after regrowth factored into the equation is likely to be
neutral in the long term.
Many replies to the statement expressed surprise that CO2 emissions
were not accounted for, but one stood out. It was carefully written
and supported the policy, despite the author's determination to remain
anonymous. However, their statement may reveal a "green insider" or a
botanist's knowledge of the issue:
The accounting rules are not necessarily closely related to what
actually happens -- they are more like convenient assumptions at this
stage of developing comprehensive accounts. However, they do influence
what happens on the ground -- what counts is what people pay attention
to.
There is very little information about fire and CO2 emissions.
>From my perspective, if we think of forests primarily as permanent
carbon stores, the impact of fire is usually relatively transient
(over periods of decades to centuries). The main objective should be
to maintain the ecological integrity of the forest, which in turn
maintains the carbon stores in perpetuity (not necessarily at their
maximum possible level, but at a level which can be sustained
ecologically through variation in climatic and other conditions). If
we start managing for carbon alone, all kinds of perverse outcomes
will result.
The author apparently knows that ecological and fuel reduction burns
are a significant source of CO2 emissions, like burning coal, but is
determined that they are not seen that way.
The most likely "perverse outcome" in the context of this statement
would be the end of ecological burning which some argue fosters of
biodiversity and helps to combat climate change.
There is a school of thought widespread among botanists and foresters
that fire is an essential tool in managing the Australian landscape.
This view holds that it helps to maintain plant biodiversity.
Aboriginal use of fire is frequently quoted, though the evidence cited
is often thin and circumstantial at best, especially for forests. But
the impact of fire on animals, stream flow and on diminishing rainfall
in Australia has been the subject of little research.
A perverse outcome of current landscape management has been the recent
rapid increase of the use of fire while its impact on CO2 emissions is
being actively denied. The views of botanists and foresters have
clearly held sway on other academics, the Greens, the CSIRO, the
International Panel for Climate Change and the Australian Greenhouse
Office.
It is illogical that fires in the forests of Southeast Asia are "of
concern" to the Australian Government while we impose carbon taxes on
the burning of fossil plants (coal), and then deliberately burn the
crap out of living plants actively storing carbon in Australian
forests.
On 10/29/08, Andrew Taylor <> wrote:
On Wed, Oct 29, 2008 at 01:12:35PM +1100, Evan Beaver wrote:
>From my own anecdotal evidence it seems pretty obvious; quite a few
trees seem to require fire to cast seed, and some need it to
germinate.
This is a bit of a peeve with me (OK I have lot of peeves) - you hear
this said a lot but if you think about it seems a sub-optimal strategy
for a plant to put all it eggs in one basket and keep all its seeds in
the canopy. I gather there is actually there is a spectrum of responses
even among famously fire-adapted groups such as Banskia and Hakeas.
Few species completely retain seeds - most release at least some seeds
between fires (google serotiny). I believe seed dormancy is similar in that
most plants which have seeds which lie dormant until a fire (germination
triggered by heat or smoke) also produce at least some seeds which
germinate inter-fire. As fire plays a large role in reproduction in many
Australian plants, I guess its more pedantry than anything else though.
Rob Whelan who has doen a lot of work on fire ecology at Barren Grounds
and other areas around Sydney has a book which I've been meaning to buy &
read: http://www.amazon.com/Ecology-Fire-Cambridge-Studies/
I'd agree with a lot Chris said. My personal opinion is that fire
management goals are often so vague, incoherent and/or unquantifiable
that the limitation of our knowledge don't matter.
Andrew
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