Contrary to previous research, it seems now that early Australians did not cause widespread ecological changes by means of fire. The most extensive study to date of charcoal remains in the continent (including also data from New Guinea and New Zealand) shows that there was nearly no change upon human arrival, maybe some 50,000 years ago.
The intensity of fires appears instead tightly related to climate. However the arrival of Europeans in the late 18th century did increase fire activity.
""While this may seem contrary to prior studies"
ReplyDeleteIt certainly does. Sounds a bit like a whitewash to me. Perhaps because they included:
"The study was based on an analysis of charcoal records at 223 sites from Australasia, including New Zealand and Papua New Guinea".
Would alter the statistics.
"The records show that bushfire activity was high from about 70,000 to about 28,000 years ago".
So maybe humans arrived in Oz 70,000 years ago.
I can't say because only a glimpse of a paper (probably still in print) has been offered.
ReplyDeleteIn any case, Mooney seems an expert in the matter.
Including NZ and NG cannot alter the record for Australia, just provide controls and extend the information to these areas.
The case is that Australia is highly flammable, more than any other such region on Earth. And when the environment is highly flammable, it eventually burns - just a spark is needed. In fact I have the impression that Australian Aborigines use of fire is intended to prevent uncontrolled fires, and hence keep themselves and the ecosystem on which they depend safer, more stable.
My intuition is that simply measuring fire frequency is not enough to know if fires were human caused or not. The amount of material available to burn may be a product of climate, but the pattern of burns may be very different. Human presence is associated with bigger burns all at once at strategic moments (e.g. when they could kill megafauna). Natural fires are caused mostly by lightening and tend to involve more fires that are individually smaller in extent (which might be less prone to kill wildlife that can flee rapidly).
ReplyDelete"Human presence is associated with bigger burns all at once at strategic moments (e.g. when they could kill megafauna). Natural fires are caused mostly by lightening and tend to involve more fires that are individually smaller in extent (which might be less prone to kill wildlife that can flee rapidly)".
ReplyDeleteOf course the following comment applies to modern times, but a fire-fighter in Australia used to say, 'There are three main causes of bush fires: Men, women and children'. He claimed a not insignifant but far smaller proportion of fires are actually a result of lightning.
"The case is that Australia is highly flammable, more than any other such region on Earth. And when the environment is highly flammable, it eventually burns - just a spark is needed".
And it's usually accepted that the vegetation of Australia changed after humans arrived, as a result of continuous burning. Until about 50-60,000 years ago the vegetation was more similar to that of New Zealand. Eucalypts were a far smaller proportion of the forest trees than they are today.
It's a very interesting subject though. A friend used to do rersearch on pollen profiles in NZ. He discovered a huge increase in fires with the arrival of the Polynesians, about 900 years ago. Earlier ones are usually associated with volcanic eruptions.
I understand that the fire control strategies deployed by Australian Aborigines are the other way around (and never oriented to the hunt): they make smaller fires to prevent the large uncontrolled ones caused by nature more rarely but also more violently.
ReplyDeleteActually it'd be roughly the same as firefighters do in many places modernly: controlled fires to clean up the fodder and prevent larger uncontrolled ones. Fires increase in any case the diversity of prairies and other fire-adapted landscapes, including many woodlands.
"I understand that the fire control strategies deployed by Australian Aborigines are the other way around (and never oriented to the hunt): they make smaller fires to prevent the large uncontrolled ones caused by nature more rarely but also more violently".
ReplyDeleteMy understanding is that the fires were to burn off old vegetation to encourage new grass for the herbivores, so they could hunt them more easily. The prevention of larger fires was a perhaps unintended consequence. In New Zealand fires were often used to keep traveling tracks open.
"Fires increase in any case the diversity of prairies and other fire-adapted landscapes, including many woodlands".
ReplyDeleteEvidently the opposite. Fire increases the homogeneity of the vegetation. It is all at the same stage of regeneration. That is one of the arguments in favour of human extermination of the megafauna. The megafauna increased the bidiversity by browsing the vegetation, giving rise to a variety and turnover of ecologies within a region, whereas fire has the opposite effect.