food and agriculture > features > world�s rangelands are turning to desert
World�s rangelands are turning to desertPosted: 11 Feb 2002
by Lester Brown
Earlier this year (2002), a dust storm originating in northwestern China engulfed Lhasa, the capital of Tibet, closing the airport for three days and disrupting tourism. Such dust storms are no longer uncommon. Dust storms originating in Central Asia, coupled with those originating in Saharan Africa that now frequently reach the Caribbean remind us that desertification of the world's rangelands is ongoing.
Even though the damage from overgrazing is spreading, the world's livestock population continues to grow, tracking the growth in human population. As world population increased from 2.5 billion in 1950 to 6.1 billion in 2001, the world's cattle herd went from 720 million to 1.53 billion. The number of sheep and goats expanded from 1.04 billion to 1.75 billion.
With 180 million pastoralists worldwide now trying to make a living tending 3.3 billion cattle, sheep, and goats, grasslands are under heavy pressure. As a result of overstocking, grasslands are now deteriorating in much of Africa, the Middle East, Central Asia, the northern part of the Indian subcontinent, Mongolia, and much of northern China. Overgrazing of rangelands initially reduces their productivity but eventually it destroys them, leaving desert. Degraded rangeland, worldwide, totals 680 million hectares, five times the US cropland area.
Rangeland in Mongolia, where much pastoral land has been damaged. Credit: Nordic Institute of Asian Studies/Ole Bruun
Rangelands, consisting almost entirely of land that is too dry or too steeply sloping to support crop production, account for one fifth of the earth's land surface, more than double the area that is cropped. Tapping the productivity of this vast area depends on ruminants-cattle, sheep, and goats--animals whose complex digestive systems enable them to convert roughage into food, including beef, mutton, and milk, and industrial materials, importantly leather and wool.
Some four fifths of world beef and mutton production, roughly 52 million tons, comes from animals that forage on rangelands. In Africa, where grain is scarce, 230 million cattle, 246 million sheep, and 175 million goats are supported almost entirely by grazing and browsing. The number of livestock, a cornerstone of many African economies, often exceeds grassland carrying capacity by half or more. A study that charted the mounting pressures on grasslands in nine southern African countries found that the capacity of the land to sustain livestock is diminishing.
Fodder needs of livestock in nearly all developing countries now exceed the sustainable yield of rangelands and other forage resources. In India, with the world's largest cattle herd, the demand for fodder in 2000 was estimated at 700 million tons, while the sustainable supply totaled just 540 million tons. A report from New Delhi indicates that in states with the most serious land degradation, such as Rajasthan and Karnataka, fodder supplies satisfy only 50-80 per cent of needs, leaving large numbers of emaciated, unproductive cattle.
China faces similarly difficult challenges. The northwest of China, where there are no land ownership rights and no fences, has become a vast grazing commons. Since the economic reforms of 1978, there has been little incentive for individual families to limit the size of their flocks and herds. As a result, livestock numbers have soared. The United States, which has a comparable grazing capacity, has 98 million head of cattle while China has 130 million head. But the big difference is in the number of sheep and goats: 9 million in the United States, 290 million in China.
In Gonge County, for example, in eastern Qinghai Province, the local grasslands can support an estimated 3.7 million sheep. But by the end of 1998, the region's flock had reached 5.5 million--far beyond its carrying capacity. The result is fast-deteriorating grassland and the creation of a new desert, replete with sand dunes.
The mounting pressures on rangelands in the Middle East are illustrated by Iran, a country of 71 million people. The 8 million cattle and 81 million sheep and goats that graze its rangelands supply not only milk and meat, but also the wool for the country's fabled rug-making industry. In a land where sheep and goats outnumber humans, and where rangelands are being pushed to their limits, the current livestock population may not be sustainable.
Land degradation from overgrazing is taking a heavy economic toll in lost livestock productivity. In the early stages of overgrazing, the costs show up as lower land productivity. But if the process continues, it destroys vegetation, leading to the erosion of soil and the eventual creation of wasteland. A UN assessment of the earth's dryland regions, done in 1991, estimated that livestock production losses from rangeland degradation exceeded $23 billion.
In Africa, the annual loss of rangeland productivity is estimated at $7 billion, more than the gross domestic product of Ethiopia. In Asia, livestock losses from rangeland degradation total over $8 billion. Together, Africa and Asia account for two thirds of the global loss.
Arresting the deterioration of the world's rangelands presents a difficult challenge. One key to arresting the growth in livestock populations is to stop the growth in human populations. Iran, recognizing the threat of overgrazing and other population-related stresses it was facing some 15 years ago, dropped its population growth from 4 per cent a year to scarcely 1 per cent in 2001, illustrating what can be done with committed leadership.
Another key to lightening pressure on rangelands is the spreading practice of feeding livestock crop residues that would otherwise be burned, either because they are needed for fuel or because double-cropping requires destruction of the residues. India has been uniquely successful in converting crop residues into milk--expanding production from 20 million tons in 1961 to 80 million tons in 2001, and without feeding grain. Its farmers did so almost entirely by using crop residues and by stall-feeding grass cut and collected by hand.
China also has a large potential to feed corn stalks and wheat and rice straw to cattle or sheep. As the world's leading producer of both rice and wheat and the second-ranked producer of corn, China annually harvests an estimated 500 million tons of straw, corn stalks, and other crop residues. Feeding crop residues in the major crop-producing provinces of east central China--Hebei, Shandong, Henan, and Anhui--has created a "Beef Belt," whose beef output dwarfs that of the northwestern grazing provinces of Inner Mongolia, Qinghai, and Xinjiang.
In rangeland reclamation, where successes are few, a promising low-cost technique for reclaiming overgrazed and exhausted rangeland is being developed at the International Center for Agricultural Research in the Dry Areas (ICARDA) in Syria. ICARDA scientists have developed a simple implement that slightly depresses the soil in double rows 20 centimetres (8 inches) apart. The implement seeds grass in these twin depressions, which follow the contour of the land, enabling them to trap rainwater runoff and restore vegetation.
It will take an enormous effort to stabilize livestock populations at a sustainable level and to restore the world's degraded rangelands. This will be costly, but failing to halt the desertification of rangelands will be even costlier as flocks and herds eventually shrink and as the resulting poverty forces large-scale migration from the affected areas.
Lester Brown is President of the Earth Policy Institute � a Washington-based non-profit organization which aims to provide a vision of a sustainable economy.