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Chapter 1
Desertification: Crisis and Opportunity
The situation (desertification) has been accurately likened to a skin disease in which existing eruptions worsen and coalesce with new outbreaks of the disease. And, as with any disease, treating the symptoms is secondary to tackling the causes.
—Mostafa K. Tolba, Harvest of Dust, Desertification Control Bulletin (1984)
The drylands and deserts of the world have been and are being damaged and made less productive by mismanagement. The causes of desertification are myriad and often interconnected: overgrazing; overcutting for firewood and timber; inappropriate farming; poor irrigation management, leading to problems with salinity, alkalinity, and waterlogging ; mining; construction of highways and utility corridors; fire suppression; military operations; air pollution; the introduction of exotic animals and plants; recreational activities, particularly off-road vehicle recreation; industrial projects; climate change; housing; and urbanization (Lovich and Bainbridge 1999). Once damaged, deserts are very difficult to repair, but I have demonstrated that it can be done. This work, combined with research and restoration by many others here and in other areas of the world, provides new hope for the world’s arid lands.
This book provides information on development of desert restoration projects based on recent work in the southwestern United States, but it is intended to help land managers in drylands around the world. I will use examples primarily from the deserts of the Southwest because this is the area I know best, but I will make connections to other drylands of the world when I can. We can learn a great deal from the past, both in how to manage lands better and in the consequences of flawed management and overuse (Figure 1.1). The hills of Jordan once had rich soils, forests of pistachio and oak, grasses, and flowers, but now they are barren and stony. The Nabataeans once had the most highly developed runoff irrigation system ever created, supporting cities in the desert where people now eke out a difficult and precarious living, but changes in politics and economics led to its collapse.
The treatment of disturbed and degraded sites can be intensive or minimal, short term or long term, by removal from use or through changes in use. In most cases the techniques and strategies developed here will also prove useful in other drylands, but I will try to suggest where exceptions and surprises might be expected.
My goal throughout this book has been to help others in the drylands of the American Southwest, northern Mexico, and similar areas around the world to
- Characterize the adverse environmental impacts of past actions
- Better understand the causal chain of events that leads to desertification
- Minimize adverse effects of current and future activities
- Develop practical strategies and methods for restoration
FIGURE 1.1. Lessons from the past: The once-forested oak and pistachio landscape of Nabataea is now a rocky wasteland. If we consider only what we see today, we will make the wrong choices in restoration planning. (Laurie Lippitt)
- Increase active restoration of degraded drylands
- Guide evaluation, research, and monitoring of damaged and restored sites
- Protect biodiversity and habitats in arid and semiarid lands
- Make resource management in drylands more sustainable
- Improve the quality of life for people living in arid and semiarid lands
The underlying causes of dryland degradation are commonly economic and cultural rather than ecological (Hallsworth 1987; Carney and Farrington 1998; Chambers et al. 1991). The limited historic success in slowing the rate of desertification and increasing restoration is linked to the consistent pattern of treating the symptoms rather than the causes. Rhetoric about the ignorance or moral failures of ranchers, pastoralists, and farmers and research on technical fixes will not solve this complex problem.
Although additional techniques for desert restoration can still be improved, the fundamental challenge remains changing the economic and cultural pressures and incentives that lead to destruction. We need to begin more accurate accounting of the economic, social, and environmental benefits and costs of resource management. The complex issues of tenure, perverse economic incentives, subsidies, natural services, social traps, and open access problems are briefly reviewed in Chapters 3 and 14, but the focus of this book is on the ecological underpinnings and technical aspects of restoration in the field. These remain similar, whether we are working in a wealthy country, with a wide array of financial, scientific, and technical resources, or a country with very few resources other than people and dedication (Aronson et al. 1993).
Overgrazing and Desertification
Globally, the most common and serious problem affecting drylands is overgrazing. It may be driven by economic pressure, greed, desperation, and, more rarely, ignorance. The American Southwest offers many examples of the perils of severe overgrazing. As Costello and Turner wrote in 1941, “The most widespread and cataclysmic change in the desert (of the United States) in modern times has resulted from unrestricted grazing.... The desert in many places is one-tenth as productive for wildlife as when white men first came on the scene.”
The rapid increase in population that occurred after the Gold Rush in California led to skyrocketing demand for meat at any price. Cattle and sheep were driven to the gold fields from the southern ranchos, Texas, and as far away as Pennsylvania. Native Americans were displaced as ranchers quickly moved to increase stocking to meet the demand. Profits were enticing, and investment from the East and abroad led to a cattle boom, with livestock on the California range reaching perhaps 3 million cattle and a million sheep by 1862 (Burcham 1957). In the drought of 1863–1864 as many as a million cattle starved to death, but before they died they ate every shred of edible material and left an impoverished flora still evident today. As with any drought, some areas were hit much harder than others. In Santa Barbara County there were 97,000 cattle grazing in the spring of 1863, but by 1865 only 12,000 were still alive.
By some estimates the severe overgrazing during droughts in the late 1800s cut the permanent grazing potential of California in half, and it is likely that the impact was even larger in the desert (Figure 1.2). Very limited recovery has taken place despite much reduced grazing pressure for more than 100 years. The invasion of yellow star thistle (Centaurea solstitialis), which dominates 20 million acres of California drylands, was made possible in part by this beef boom and collapse, the sheep boom of 1880 (and subsequent collapse), and the continued overgrazing on already damaged rangelands for the last one hundred years.
In other areas of the Southwest the beef boom came later as refrigerated rail cars made it feasible to ship meat to the East Coast. Enormous profits often were made for a few short years, followed by total range collapse, declining beef prices, and bankruptcy. Theodore Roosevelt’s experience with his ranch in Dakota Territory was typical. He lost $40,000 between 1883 and 1887, and by 1887 it was said, “The grass was eaten off until it looks as if it had been shaved with a razor.”
The legacy of this exploitation remains clear today, and by some estimates less than 5 percent of the western range is in natural condition, and two thirds of it was in poor or very poor condition in 1976 (Forest Service 1980).
The same forces are at work in the growing rangeland catastrophe in western China (Brown 2003). Increasing trade liberalization and the race to the bottom (transferring manufacturing to areas with limited environmental and labor protection) have led to an expanding middle class in China. With growing prosperity has come an increasing demand for meat, and the pressure to produce new meat has focused on the fragile lands of western China. Production has increased rapidly, from 1 million tons in 1989, to 3 million tons in 1996, to 5 million tons in 1999. In Mongolia the livestock population soared from 2 million in 1987 to 18 million in 2000. Profits have been good, but the dust bowl in the making appears likely to overshadow the destruction of the American Southwest in the late 1800s (Secretary of Agriculture 1936; Sheridan 1981).
The decline of arid or semiarid rangeland often is a chain of events with positive feedback, triggered by drought, resulting in a step-by-step decline that is very hard to stop (Figure 1.3; see Chapter 3 for more detail). As a drought deepens, range managers are reluctant to cut herd size because everyone would be selling their animals at the same time, and this would ensure minimal market prices and severe economic losses. During a recent drought in Australia sheep were selling for a dollar apiece, yet there were few takers. Why sell at the bottom and take such a big loss when it might rain tomorrow or next week?
As the range is stripped of edible food, the pressure on remaining plants increases, and after everything else has been eaten ranchers may burn the thorns off the cacti so they can be eaten, too. The soil structure is degraded, and soil cryptobiotic crusts are severely damaged. The soil no longer captures water, and recovery is very slow.
The range is left barren and slowly recovers to a fraction of its original potential, but the herds also recover, and the next drought leads to a crash that is even deeper. Often a change from cattle to sheep takes place, and this enables the rancher to return to higher grazing levels because sheep eat different plants than cattle. After the sheep finish with a range, the next stage is a shift to goats or camels (Figure 1.4). These animals will eat almost anything, and the stage is set for a stone and gravel desert. This transition can be very rapid if the pressure is high enough but is more commonly a slow decline reaching bare rock after decades or hundreds of years instead of months.
FIGURE 1.2. Overgrazing is a very common problem. (a) Historic overgrazing in the Southwest often was catastrophic. This ranch had 30,000 head of cattle (X6155, Keystone Mast Collection, UCR/California Museum of Photography, University of California at Riverside). (b) The fenceline tells the tale.
FIGURE 1.3. The pattern of rangeland decline.
As vegetation is removed, more rain runs off instead of entering the soil. Diminished long-term water availability limits vegetation growth and the resistance of stream channels, and as flood flows increase gullies may deepen quickly. The arroyo shown in Figure 1.5 developed almost overnight in one severe storm event. As gullies become deeper, water tables may lead to groundwater drainage into the arroyos and a quick increase in d...
