Tag Archives: fire

Nice Piece on Burning in the Stanford Report

As part of a series of articles on interdisciplinary environmental research at Stanford, the Stanford Report has just published a nice piece on the research on Aboriginal burning in Western Australia led by Rebecca and Doug Bird. This work is supported by a grant from the Woods Institute Environmental Venture Project fund as well as a major grant from the National Science Foundation.  We have a fairly recent paper in PNAS that describes some of the major findings, which I have written about previously here.

We've got some exciting things in the works as a follow-up to this paper thanks to the EVP funding. These include agent-based models of foraging and its effects on landscape development and new statistical methods for characterizing the scale and pattern of burning-induced landscape mosaics.  We're also hoping to move into some comparative work across foraging populations and to expand upon the ecological interactions between human foragers and plant species upon which they depend.

Some Thoughts on the Fires Down Under

I recently received some comments on my post describing our PNAS paper from the end of 2008 in which we demonstrated that aboriginal burning increases grassland biodiversity.  The comments were very angry -- and a little incoherent.  Clearly, emotions were (and are) running high in Aus following the the tragic bushfires in Victoria that have killed at least 181 people. An interesting, though rather vague, editorial appears in today's The Australian in which foreign editor Greg Sheridan argues it's time to get serious about preventing future tragedies of this kind.  He rightly notes that all the hysteria over global warming is of little practical consequence for managing wildfires. Global warming is, in my opinion, a reality and the best evidence we have suggests it is driven by human action.  Nonetheless, we can not attribute any one event, however dramatic, to global climate change.  Furthermore, blaming the fires on global warming does nothing to mitigate the effects of future fires (which are inevitable both in Aus and here in the American West). If anything, I fear that the linking of these fires to global warming disempowers people for action because they feel like they have no control over forces so much larger than themselves.

One of the comments on Sheridan's editorial really struck me (and I thank Brian Codding for bringing this to my attention).  "Steve from Hobart" wrote quite eloquently on the topic (I have attempted to edit some of the characters that didn't translate from Steve's word processor to The Australian):

The call for controlled burning has long been sounded in this country without being seriously implemented by State and Commonwealth governments of either political persuasion. The Royal Commission after the 1939 fires clearly indicated that such land management practices should be diligently implemented -- long before there were any "greenies". Similar calls came after 1967 in Tasmania, 1983 in SA and Victoria, and more recently in NSW and certainly in Canberra. Conclusion: the inaction on implementation of a systematic, cyclical prescribed burning regime is not new, so be careful about laying the blame on any particular group. Issue 2.: controlled burns a threat to biodiversity??? Perhaps it might be if such burns are only carried out when the fuel load reaches ridiculous proportions, and/or it's allowed to cover very large areas. Controlled burning is something that the ecology and biodiversity of this country thrives on, and it would appear that it has actually evolved to take advantage of a cyclical fire regime. Ask the indigenous people, they practised it for millennia. We need to make a serious effort to revisit that strategy, and not just on the urban fringe. We need to do the ecology and biodiversity of our magnificent and unique country a favour, and try to develop a modern-day fire-stick farming regime for our forests. Regular patchwork burning of smaller areas, repeated on a regular cyclical basis. And, in so doing, we'll protect human life and property.

Well said, Steve!

Here, I will copy what I wrote in response to the heckling I received regarding my previous post because the points are, I think, worth emphasizing. I was responding to extreme skepticism that ecology had anything to do with fire control and that human agency has anything to do with ecology. Again, I will edit slightly.

The tragic fires currently devastating large tracts of Victoria actually highlight the need for carefully done fire ecology. The recent events in Australia dramatically underscore this as do the enormous wildfires that have beset us here in California and the American West more generally over the past decade. So far, we have not experienced the degree of human tragedy that you are seeing in Victoria, but I fear it is just a matter of time.

Following the classic definition by Andrewartha and Birch, ecology is the scientific study of the distribution and abundance of life. If human burning affects either the distribution or abundance of plant or animal species — which it certainly does — then it is the proper subject for ecological analysis. Furthermore, ignoring human agency in such a case would yield a trivial and incomplete ecology.

In our paper on the fire-stick farming hypothesis, we actually make no claims of relevance to contemporary problems. We are trying to understand the dynamics of this particular system. That said, I nonetheless think there are findings of policy relevance embodied in this work. Fire needs fuel and the fuel for wildfires is the vegetation in “wild” areas. As you note, there are no parts of the world untouched by human influence either directly or indirectly. By setting many, small, low-intensity fires through their subsistence hunting, the Martu alter the landscape and make it less flammable. In effect, the successional mosaic that arises from this practice creates a landscape of firebreaks. This is precisely what back-country fire-control teams do in battling wildfires. The Martu just do it preemptively.

How to manage highly flammable landscapes in more densely settled areas like coastal Australia and the American West is an enormous problem and I don’t claim to have the answers. However, ideas informed by landscape ecology are clearly part of the solution. Engineering human-dominated landscapes with greater structural heterogeneity seems essential for dealing with this emerging chronic problem of arid temperate and sub-tropical climates.

Doug Bird, Rebecca Bliege Bird and I are working on longer essay that addresses these vital problems of contemporary human ecology.  I will, no doubt, write about that again here soon.

Press on our PNAS Paper

Our new paper at PNAS has been out a day now and Wired Magazine has already done a story on it.  It's a nice piece but it gets several things hilariously wrong. It says:

Bird's team recently published a study on "fire stick farming," a traditional method of ecosystem management still used by aborigines in Australia's Western Desert. By burning wooded areas, lizards are driven towards hunters; cookpot-friendly kangaroos and emus fatten themselves on grasses flourishing on newly cleared lands.

The thing is that (1) Martu don't use fire to drive game, and (2) Murtu don't burn woodland -- only spinifex grassland.  That's really what drives the process.  Spinifex may be bullet-proof.  It may puncture the tires on your Land Rover. It may eat other plant species for breakfast.   But, boy, does it burn!  By burning spinifex, Martu hunters open the grasslands up for colonization by early successional species that couldn't otherwise compete.  From a hunter's perspective, burning increases access to goanna burrows and therefore  increases foraging returns.

Science reporting is hard.  You have to turn around comprehensible -- and compelling -- stories on tight deadlines.  It's nonetheless a shame that this piece gets such a fundamental piece of the story wrong.  One thing that is very nice, however, is that there is a link to the actual paper.

Aboriginal Burning Promotes Grassland Biodiversity in Australia’s Desert

We have a new paper out in this week's Proceedings of the National Academy of Sciences Early Edition.  The paper suggests that subsistence related burning increases local landscape heterogeneity and may promote biodiversity in Australia's Western Desert.  What's really interesting about this is that promoting biodiversity is not the goal of individual hunters – they are really just trying to maximize their foraging returns.  My Stanford Anthropology colleagues Rebecca Bliege Bird and Doug Bird have been working with Martu foragers in Western Australia since 2000.  They gather amazingly detailed quantitative ethnographic and ecological data, focusing on such classic problems as understanding subsistence economy in a foraging population and the ecological factors favoring a sexual division of labor.

Martu foragers burn the climax spinifex grass in search of goanna lizards and in so-doing, promote the growth of plant species that cannot compete with adult spinifex, which is a nasty grass with high-silica content:

Spinifex is extremely flammable and once a fire is started in a patch, it will race through until it is pretty much all burned.  The vegetation that characterizes other successional stages is far less flammable.  Previous work by Doug and Rebecca has shown that burning increases hunters' encounter rates and probability of capturing goanna lizards and other prey species. 

Using their detailed information on hunting and burning, we correlated foraging activity with measures of habitat heterogeneity derived from satellite imagery.  We compared local habitat heterogeneity in areas where Martu were actively foraging (and burning) to areas where there was no foraging and the fire regime was instead driven by lightning ignitions.  What we found was that the heterogeneity in the foraging localities was greater than in the "natural" burn regimes.  In particular, foraged localities had remarkably uniform distributions of successional stage.  The non-foraging localities would show peaks at different successional stages -- depending on the age of the last burn -- but the frequency of whatever stage was present would typically fall off from whatever the characteristic mean was.  In contrast, the successional stage distribution we observed in the foraged localities looked like a mixture of several different smaller "natural" localities.  This is because that's essentially what they are!

When people burn for subsistence needs, they tend to start lots of small fires at many different times.  What results is a mosaic of successional stages. But this is really a local re-arrangement.  When we looked at the landscape level, the diversity of habitats looks very much like that of the smaller foraging localities.

One interesting implication of this work is that the human impact on the Australian environment -- grassland engineering, if you like -- was likely to only be substantial following the establishment of more intensified aboriginal economies (approximately 1500 years ago).

It may seem counter-intuitive that hunting with fire promotes biodiversity, but that really seems to be what is happening here.  The results have clear conservation and management implications. Excessive fire suppression in highly flammable grasslands is probably not a good idea.  Now we need to measure the actual species diversity rather than simply the diversity of habitat types.

See Rebecca's fire ecology website for more on this research and reprints of various papers.  The full text of our paper can be found here.