|CERES No. 098 - March - April 1984 (FAO Ceres, 1984, 50 p.)|
To preserve precious agricultural land the Chinese are mounting a major campaign against encroaching sand
Figures concerning population and arable land in China have been cited often enough, but they bear repeating in any consideration of land use in that country. With only slightly less than one quarter of global population, China must make do with less than 10 per cent of the world's arable land. This works out to about 0.1 hectare per caput.
Pressures on agricultural land are thus enormous and increasing, as a result not only of population growth per se but also of the attendant economic and social pressures. One recent Chinese estimate is that between 1957 and 1977 the nation lost nearly 30 per cent of its farm land a total of some 33 million hectares. About 20 per cent of this loss was attributed to urban and industrial development, but the rest was due to various forms of land degradation, namely, deforestation, erosion, desertification, waterlogging, and salinization.
By no means the least of these has been desertification. The Academia Sinica estimates that during the past half century encroachment by desert on arable land has been at the rate of 1 000 square km per year. Added to another 120 000 square km that became decertified during previous historical periods, a total of 170 000 square km has become desert as a result of human actions.
Most of China's decertified land is distributed along a wide belt across the northern part of the country; including the western part of the northeastern plain, the vast area to the east of the Tarim Basin, to the north of the Great Wall and the Kunlun Mountains, and to the south of the Sino-Mongolian and Sino-Soviet borders. In all it encompasses more than 200 counties with a total population of about 35 million.
In addition to this, Chinese scientists calculate that another 150 000 square km are at risk of desertification if the land is used improperly.
Even if the threat of desertification falls mainly in some of the less densely populated regions of China, the overall implications for a country with China's land-to-population ratio are disturbing, and in recent years the Chinese have been accelerating planning and programmes intended to counteract the menace of the desert.
Lessons from history. A focal point of campaign strategy in this struggle is the Lanzhou Institute of Desert Research, an offshoot of the Academia Sinica. It is located on the fringes of the sprawling industrial city of Lanzhou, which straddles the Yellow River as it cuts across the province of Gansu to make a vast loop into Inner Mongolia. The Institute has a quarter of a century of experience in the development of desert control measures. Its present director, Professor Zhu Zhenda, who has been with the Institute since its inception spent 10 years in the forbidding
Taklimakan desert of the Xinjiang Autonomous Region (In local dialect the desert's name translates into (You can get in, but you can't get out.") There, mute testimony to the relensless historical advance of the desert can be found in the eroded ruins of Kroraina, which 16 centuries ago was a prosperous city of 10 000, an important stop on the ancient silk route out of China. Today it is a wastelaml, accessible only by camel. Nevertheless, some students of the archaeological and anthropological evidence from these areas are convinced that there was considerable agricultural productivity in the distant past that was lost through poor fanning practices and overgrazing. "In my mind," says Professor Zhu, "there is great significance in studying the historical processes of desertification."
There is opportunity to do so without making the arduous journey to the ruins of Kroraina.
Some 250 km north of Lanzhou in Ningxia Hui Autonomous region one can witness how the desert has gradually swept itself over the Great Wall of China, burying it completely in many places, eroding the exposed rocks in others. Zhongwei, on the northern slopes of the Yellow River Valley and on the main rail line built from Beijing to llruma in the 1950s, is a front line encampment in the battle against the desert. Nearby, in the valley of the Yellow River itself, is the Shapotou Research Station, one of the outposts of the Desert Research Institute in Lanzhou.
It is along this strip where the railroad touches the southern perimeter of the Tengger desert that the battle to control the drifting sands can be seen in its most dramatic form. Two or three kilometres north of the rail line a county road peters out amid 30-metre high sand dunes, where, even on a relatively calm day, a fine spume of whispering sand jetting out from each dune peak testifies to the ceaseless motion of the desert. Beyond this point, transport is by camel train, the only means of going "inside the desert".
One quarter survive. From the desert's edge back to the railroad, one can trace the step-by-step strategy used to control the shifting dunes. The first line of defence, looking almost like a caricature of the Great Wall of China itself, is a fragile two" metre-high fence of woven willow that follows an uneven course along the upper ridges of the undulating dunes. Its purpose is to check the more severe effects of the winddriven sand, providing more shelter for the leeward side of the dunes, which are then stabilized with a checkerboard grid of straw tamped deep into the sand Within each square metre of the grid a single seedling of one of three hardy species (Caragana boschinski, Hedysarum sopariaum, or Artemisia ordesika) is planted. This method of binding the sand with straw has been adapted from one used by peasants of the region, with whom desert researchers have worked closely.
Although planting is normally undertaken after one of the region's sporadic rains, the station workers expect only a 25 per cent survival rate from the initial planting, except where irrigation is possible. Nevertheless, as one continues back from the desert's edge toward the rail line, results of previous plantings become apparent. Some of the surviving shrubs and trees are half buried in shifting sands; others have had their roots exposed where the winds have whipped away the side of a dune. Yet, little by little, these straggling ranks of trees are closed. The protected belt on the north side of the railroad ranges from 700 to 1000 metres in width and only the first 50 of these are irrigated by water pumped from the Yellow River.
Yet the narrow belt of greenery is serving the purpose for which the Shapotou Research Station was originally set up in the mid-1950s: to protect the new railway line from the drifting sands, which by that time had already crossed to the south banks of the Yellow River at some points. The bonus from the work at Shapotou has been the demonstration that not only is it possible to stop the forward movement of the desert and to stabilize the dunes, but also to reclaim the protected areas and literally to transform them into productive soils. This process of transformation becomes increasingly evident as one moves south from the railway line down the valley slope to the Shapotou station itself. There, since operations at the station began a new layer of topsoil about 30 cm deep has been created. The factors involved in this act of creation include the silt that is carried up with the irrigation water from the Yellow River which contains many properties of soil fertility, as well as green manuring with legumes as an initial crop. Station scientists estimate that it normally requires 10 to 15 years to establish a sufficient depth of topsoil for satisfactory cropping. In addition to the legumes mentioned (Astrocycles adsurgens) the station is growing pears, peaches, grapes, soybeans, and safflower.
Replicable success? Thus, while the initial purpose of the station was to protect an important transport link, it has become clear that the agricultural possibilities revealed have become increasingly important. Shapotou managers take modest pride in thc fact that communes within the surrounding county have already reclaimed some 7500 hectares of land from sand dunes and put them into crop production by using methods based on the experience at the station The county government is now expecting to add to this another 5 000 hectares over the next four or five years.
The experience gained at Shapotou will obviously be of value also in the Chinese Government's much broader campaign to combat soil erosion and land degradation across the 11 provinces of northwest, north, and northeast China where desertification is most serious. Government allocations for this "Three North" project are reported at RMB 1000 million (about US$500 million) for the period 1980-90. The project puts priority on combatting soil erosion by encouraging forestry and pasture development and the planting of shelterbelts along roads, rivers, and canals and around villages and houses. By 1990 it is expected that nearly 6 million hectares of forest will have been planted in the region, thus increasing forest coverage from 3.1 to 4.3 per cent of the total area.
Scientists at the Desert Research Institute recognize that achieving repetition of the successes of the Shapotou station on a much broader front will not be easy. Desertification as a process takes place under a variety of natural conditions and the required measures for control and for reversing the process vary accordingly. Even within the same natural zones, the degree of desertification may differ significantly and thus alter the type of corrective action required.
In their methodical approach to combatting the encroachment of sand, Chinese scientists have even classified desert movement according to speed: slow is less than 5 metres annually; medium speed is from 5 to 10 metres annually; fast deserts are those where dunes are advancing at more than 10 metres each year.
An unstable state. Scientists at the Lanzhou Institute divide decertified land into three categories: first, the region where decertified land is scattered through semi-humid zones; second, areas where desertification is developing in the steppes and in semiarid or in desert zones; third, areas where desert sands are advancing and fixed or semi-fixed sand dunes are being reactivated.
Within the first of these categories, provided that the ecobalance is not further destroyed, a few slight measures may often bring about the process of self-reversal. Even within the second category, there exists the possibility of reversing the trend toward desertification, but the process is much slower and less certain because of the fragile ecobalance. Any further aggravation of the desertification process renders the possibility of self-reversal smaller and smaller. For already decertified land in the arid steppes and desert steppe zones, there is generally no possibility of self-reversal after the ecobalance has been destroyed, because natural conditions are so severe.
Desert researchers emphasize that the historical processes of desertification rarely follow a simple, undeviating course, at least not until an advanced stage is reached in which all human activity has ceased in the area. Instead, because of repeated substitution of one type of agriculture or animal husbandry for another and under the influence of variable amounts of precipitation each year, desertification follows an uneven pattern of expansion interspersed with temporary intervals of stability or even recession. These fluctuations are further affected by the growth of population and the intensification of economic activity. Essentially, the ecological system is always in an unstable state, but the general trend is toward increasing desertification.
In a report published about two years ago, the Lanzhou Institute identified the chief causes of modern desertification in north China as follows (figures indicate the percentage of total area desertified in modern times):
Almost all of these causes, the study points out, reflect the pressure of population growth. "Therefore," the study concludes, "it is of essential importance to control the growth of population in order to restore the ecological balance and to reverse desertification."
Quite aside from long-term national policies to restrict population growth, China's campaign against desert encroachment embraces an impressive range of more immediate measures, all tailored, as at Shapotou, to match local conditions. The basic objective, however, is to combine agricultural and forestry activities within a forest shelter framework to create, eventually, a stable "eco-structure". It puts emphasis on forage production to ease the pressure of livestock on grazing land. It stresses careful, overall planning of the drainage areas of river systems to determine a rational and equitable distribution of water between upper, middle, and lower reaches of the system.
Failures in funding. Besides sharing techniques of desert control with peasant communities across north China, scientists from the Lanzhou Institute have shown themselves eager to exchange experiences internationally. Institute personnel participated in the 1977 UN Conference on Desertification, and subsequently arranged two international seminars at the Institute, in 1978 and 1981.
It remains to be seen, however, whether the priority that China has accorded her own schemes for desert control will provide new impetus to the global campaign against desertification that was launched seven years ago. A two-year survey just completed by the United Nations Environmental Programme (UNLP) has found that the worldwide threat of desertification is increasing in severity. The survey estimated that a total of nearly 3.5 billion hectares of the world's range, rainfed cropland and irrigated land - an area approximately the size of North and South America combined - is affected by desertification. And each year, another 21 million hectares is reduced to a state of near or total uselessness.
Even more disturbing, however, is what UNEP Executive Director Mostafa K. Tolba has called "the absurdly inadequate" level of contributions to the special account set up five years ago to finance a plan of action agreed upon by 94 countries at the UN Conference on Desertification in 1977. At the end of last year, contributions totalled less than $50 000, all from developing countries. Meanwhile, over a six-year period, an effort mounted by the UN General Assembly to mobilize funds needed to halt desertification has raised only $26 million as compared with an estimated annual requirement of $4.5 billion for the next 20 years. The apparent unwillingness of nations to tackle desertification, says Tolba, reflects a failure to recognize that desertification and other threats to the planet's life support systems are causing social and political breakdowns "which in turn threaten our tenuous global security".
"The main difference," he says "between UNEP's understanding now and seven years ago of the nature of the problem is a more thorough appreciation of the universality of its impacts and causes which extend well beyond the drylands most immediately affected. Desertification results not only in the loss of nations' productive resource base but also in the loss of valuable genetic resources, increase in atmospheric dust which could have as yet unknown consequences on the global climate, disruption of natural water recycling processes, loss of markets... The list is long."
Tolba's warning, and the findings of the UNEP survey, will be placed before a special two-day session of UNEP's Governing Council in Nairobi in late May.