One further thought about fire. From my observation "fires aren't fires".
An area behind our house was lit up by a pyromaniac on a hot Summers day.
That was a very fast spreading and hot burn and has now (about 9 years
later) regenerated to something like the grassy woodland it was beforehand.
Another area nearby was burnt in midwinter about 7 years ago as hazard
reduction (ie a cool burn, but still quite quick spreading). It has turned
into an area of very dense scrub with next no grass.
In Tanzania, Mikumi National Park was burnt, deliberately, in the cool
season. This was a very cool burn and spread very slowly: as far as we
could see the only animals killed were insects - much to the delight of
marabou storks which arrived in large numbers. The larger herbivores
benefited from the regrowth of grass that occurred. I think this is similar
to the burns in the North of Australia
-----Original Message-----
From:
Behalf Of Chris
Sanderson
Sent: Tuesday, 5 April 2005 10:18 AM
To: Colin Driscoll
Cc: Giles Mulholland;
Subject: Fuel Reduction Burning
Hi all,
It's not really as simple as completely excluding fire, or burning
every year. In Australia our plants and animals have evolved with
fire since the last climate shift made us an arid climate in the
central band of the country. To completely exclude fire would destroy
many different habitats across the country, not just through the huge
fires that could rage out of control once the fuel load was high
enough, but from the natural succession that would take place as a
result if the areas didn't burn. Many of our plant communities
require burning every 10-15 years to remain healthy and diverse (Mulga
stands to name one). More or less frequent fires can destroy those
communities either through death or natural succession. In areas with
a history of fire-dependence (i.e. dry schlerophyll, acacia scrub),
fire ecologists now recommend that any Australian government identify
key habitats that need to be preserved, and use a mosaic patch burning
system that allows small areas to be cycled over a 5-25 year burning
program. This so far seems to preserve the most biodiversity and
allows many different habitat types to be preserved. This all changes
in rainforest (which should never be burnt unless you want to remove
the rainforest) and urban areas, where safety often takes higher
precedence than conservation.
(NB: this only applies to fire induced climax communities, any habitat
that doesn't require fire to maintain its plant structure should never
be burnt).
As a rough guide, to preserve the diversity of a desert area, it
should burn every 50 years (on a natural cycle, it really shouldn't
need human induced fires), a semi arid area should burn every 15-25
years, a dry woodland every 5-10, and grasslands every 2 to 5 years.
Yearly burning doesn't even help a grassland much. The goal is to
maintain the current plant communities present, rather than facilitate
a change in the habitat. Obviously the actuality of both lightning
strikes and traditional aboriginal burning practices are a little more
complex than this, which is why the mosaic patch burning at different
ages is recommended.
As far as endangered plants and animals are concerned, a properly
managed mosaic burn should leave many refuges for these to recolonise
from, and a proper cold burn should allow many animals to escape the
fire (in a perfect world mind you). For really small remnant patches,
there's no hard and fast rules because of lack of refuges, and the
inability to patch burn. You either burn and kill the plants and
animals, or don't burn, and have their habitat disappear.
The question here shouldn't be "should we burn", it should be "how can
we make it ecologically sustainable".
Regards,
Chris - Broome
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