Thursday, September 29, 2011

Restoring grasslands to their former splendor?

I'm sure many of us have heard about the problem of desertification, particularly in Africa, but also across large swaths of America (remember the Dust Bowl of the 1930's?). Well, today a very interesting article appeared in the Atlantic, looking at grassland management and preservation, what's been done wrong in the past, and how to fix it using nature's own techniques. Here's an excerpt.

The underlying technique is called holistic management, and was developed by biologist Allan Savory in Zimbabwe (then Rhodesia) beginning in the 1960s. He saw that the arid grasslands on which the region's people, livestock, and wildlife depended were succumbing to desertification. In looking for a solution, Savory recognized that the grasslands had evolved out of a symbiotic relationship with large, grazing herbivores. In time he saw that the same was true of similar ecosystems around the world, including that of western South Dakota and the rest of the Great Plains, with its once-great herds of bison.

In arid environments, plant matter doesn't degrade easily on its own -- it needs these large animals to break it down in their rumens and stamp it into the ground and generally work the land. This was accomplished naturally: As the herbivores traveled in large herds for safety against their predators, they would cause a great disturbance to the land; then, for their own sake, they would leave and not return until the plants had had enough rest to regenerate.

Now take away the Great Plains' bison, or the equivalent animals elsewhere, and replace them with cattle, property lines, and fences. The equation still includes large, grazing herbivores, but because they are relatively stationary within the landscape, the symbiosis is lost. Certain areas are overused, and elsewhere plants simply oxidize and die off from under-use; microorganisms decline, water cycles fall apart, and the land gradually collapses.

The basic premise of holistic management is to use livestock like wild animals. But whereas bison on the Great Plains moved through the landscape by instinct, now ranchers must supply that direction. Rather than simply turning cattle into a pasture, these ranchers conduct them like a herd, concentrating bodies to graze one area hard, then leaving it until the plants have regenerated. The effect can be tremendous, with benefits including increased organic matter in the soil, rejuvenation of microorganisms, and restoration of water cycles.

According to Howell and his colleagues, there can also be an exponential increase in the land's ability to sequester carbon. Savory explains in his paper "A Global Strategy for Addressing Global Climate Change" that there are already 12 million hectares (29.7 million acres) of rangeland managed holistically in Australia, Africa, and North America. Increasing those soils' organic matter by one percent would remove 3.6 gigatons of carbon dioxide equivalent (CO2e) from the atmosphere. (For context, he offers that "the annual total emissions from all sources for the year 2000 was an estimated 44 gigatons.") Savory goes on to argue that increasing the organic matter by just 0.5 percent across all of the world's 4.9 billion hectares of rangeland would sequester 720 gigatons of CO2e; increasing it by two percent would sequester 2,880 gigatons. In a nutshell, the Brown Revolution consists of sequestering massive amounts of carbon by bringing holistic management to the world's arid grasslands.

"It has to be done on a freaking massive scale," Howell says, "so it's going to require huge flows of capital to make it work. We're not going to own the whole world, but hopefully we're going to be a significant player at the table and influence land management policy on a global scale."

Howell's goal is two-fold: to implement holistic management on enough land as to have an impact on climate change, but also to provide a model that becomes the standard for grasslands management around the world.

There's much more at the link. It makes very interesting reading.

This African boy, who's seen (up close and personal) the Sahara, the Kalahari and the Namib Deserts expanding for years, hopes and prays that the project will succeed.



Anonymous said...

It will probably take more than rotating the cattle through smaller pastures on a schedule. This does help, as my family showed in our ranch operation.

But the second required part is to have herbivores that eat different classes of plants added to the rotation. As evidence, the recent news stories that showed in Africa that cattle did much better in some years when zebras grazed alongside them. The large savannahs evolved with diverse groups of herbivores grazing and using different plants, with a net benefit to all species who survived selection to make the group.

The next question is what other herbivores we can add to our cattle culture to make this work.

Here in Texas there is some cross-benefit between our cattle and the whitetail deer, but our pasture processes don't really make much for the deer. We may have to radically change our monoculture approach to pasture to get the real benefits.

Our bison might make a good choice. After hauling more hay than I want to remember back and forth from the fields, an animal that can make its own way is an attractive choice. Keeping up fences they couldn't break might not be much fun on the other hand.

acairfearann said...

Interesting article. As the author noted, the importation of humid climate habits into arid ones is at the root of it. The best example of that is grass. Native North American prairie grasses (and the host of other plants) tend to have root systems going down feet, sometimes tens of feet, as opposed to European grasses, such as the misnamed Kentucky bluegrass, along with timothy and orchard grasses (and almost all lawn grasses). The European grasses are mostly rhizomatic and are not designed for prairie/desert climates, which includes the entire Missouri/Mississippi watersheds as well as the high plains of the article. The native North American bunch grasses however, hold soil better, can get at more nutrients and more water, and are more resilient when faced with drought. They do not, however, withstand year-round grazing or higher stock numbers as well, no surprise when comparing the intensely managed European agriculture versus open range. In Europe millenia of intensive agriculture combined with a humid environment would naturally favour shallow rooted, fast growing species. Most crops, including corn, are equally shallow feeders, incapable of retaining water in the soil or accessing nutrients below the first few inches.
It would be interesting to know if the native African prairie grasses have similarly deep root systems.

trailbee said...

I live in northern CA and compared to TX I think we have much less cattle, but do have lots of grazing land per head. Within the last couple of years, especially after a wet winter star thistle has sprouted like crazy, which the cattle cannot eat. Is there such a plant in TX, or even in Africa, which stops grazing? I would imagine that this affects the grazing/land relationship in the article.