Archives for June 22, 2005

I am passionate about Australia’s rangelands. They cover about 75 percent of the land area of this continent – according to a website that I’ve just discovered.
The Australian Burea of Statistics (ABS), from memory, suggests about 60 percent of Australia is rangeland under pastoral lease.

I am not sure how these vast areas should be managed. I know they are changing – always changing.

Some in the rangelands subscribe to a book published by Allan Savoy in 1999 titled ‘Holistic Management’. I can’t get my mind around much of what Savoy writes, but I do think he raises some important issues.

While I have posted some pieces at this blog that promote the use of fire, Savoy has a very different perspective. He suggests,

“The world was not terribly overgrazed before modern humans, despite animal numbers that are unimaginable today, due to the constant movement of large herding herbivores. Constant movement was brought about by one of the defense mechanisms large grazing herbivores developed to coexist with high numbers of pack-hunting and other predators in a functioning whole. Most herding herbivore females do not have horns or other means of defense. Males generally use their horns for dominating other males and defending territory rather than protecting females and young. So to survive, females of herding herbivores seem to have developed similar strategies – drop all young over a very short period to overwhelm predators, and combine in large herds, which predators fear.

What had the bunching into very large herds to do with minimizing overgrazing of plants and maintaining plant and soil health? This is easy to understand if we look at plant physiology research rather than range research, as the Frenchman Andre Voisin (1988) did over 50 years ago.

What Voisin discovered was that overgrazing of plants is a function of time of exposure and re-exposure of plants and not a function of animal numbers. Concentrated herds of grazing animals feeding with their mouths close to the ground, dung and urinate in high concentration and thus are obliged to move off any ground within a short time and not return at least until weathering has cleaned their feed.

No creatures normally will feed on their own feces, or that of closely related species. Such constant movement, involving short periods of plant exposure followed by a longer period during which plant recovery could take place, would have minimized the overgrazing of plants (only individual plants, not whole ranges, can be overgrazed). And in fact this is just what we experience with holistic planned grazing (described in Holistic Management: A New Framework for Decision Making (Savory and Butterfield, 1999), which simulates nature’s grazing of old.

I believe, as we build our knowledge, we will come to understand that just as soil cannot develop without life, so grassland soils could not have developed without grass, and that grass was mostly as animal-dependent as the animals were grass-dependent. Nature only functions in wholes and patterns. With vast numbers of herbivores, as there simply had to be for the world’s grasslands and their soils to have developed, most vegetation would be grazed by year’s end, leaving little combustible material at the time of most frequent lightning.

Today not only is burning by humans more widespread and frequent than probably at any time in history, but I believe lightening fires are more prevalent in grasslands than would have been the case before humans killed off most herbivores. Where rapid biological decay previously prevailed, today we see gradual chemical/physical breakdown providing billions of tons of highly inflammable material over vast areas of rangeland and certain forests in the U.S., Australia and elsewhere. Toward the season of most lightening, much of the land is a tinderbox simply waiting to be ignited. In addition, the more we humans use fire as a tool to maintain grasslands or forests, the more fire-dependent and flammable the vegetation becomes.”