Fjölrit RALA - 05.12.1999, Blaðsíða 103

LlU XlNMIN ETAL.
101
Naiman Experiment Station has completed a demonstration experiment in the Yaole-
dianzi Village and reversed desertification by readjustment of Iand use structure, inter-
plantation of erosion-resistant grass and crops, and maintenance of stubbles and resi-
dues. Before the demonstration experiment, the village had more than 220 ha of crop-
land and 500 ha of rangeland. Most of the cropland was rain-fed. The newly cultivated
rain-fed cropland has suffered from severe soil erosion, with a maximum loss of fertile
top soil of about 3,900 tons per hectare in a year (Xu Bin et al. 1996). At the same
time, wind erosion caused changes in relief of ground surface which in tum further
changed the erosion pattems. The vicious circle of more expansion of rain-fed crop-
land, more destmction of vegetation and soil structure and poorer production leads to
extremely severe desertification. Through readjustment of land use structure, the 100
ha of the cropland in depressions has been transformed to irrigated land with higher
production, equipped with 12 wells and pumps. About 20 ha of rain-fed cropland have
been inter-planted with grass, and stubbles and residues are maintained in winter and
spring. About 100 ha of rain-fed cropland has been abandoned and transferred to natu-
ral rangeland by revegetation. As a result, under the same condition of population
(about 105 people), the total production of agriculture and animal husbandry has dou-
bled and the vegetation coverage increased from less than 15% to more than 25%.
In the regions with large areas of rangeland on gently sloping sandy ground the de-
sertification is mainly caused by over-grazing and over-gathering of fuelwood. It is,
however, a very difficult task to release the rangeland from over-grazing pressure di-
rectly by decreasing the number of domestic animals, because that could temporarily
decrease the production of animal husbandry and have a great impact on the popula-
tion. A part of the population has been organized and migrated to the above-
mentioned sand dune area to construct 'small biosphere’ and a part of them organized
to manage leather and wool factories or to build reservoirs. This organization makes
lighter grazing system possible. From a long-term point of view, a fundamental meas-
ure for wind erosion controlling in sandy rangeland is the establishment of shelterbelt
networks. In the study region, the distance between the main protective forest belts
was taken as 200-300 m. The main belts are composed of four rows of trees and two
rows of shrubs. The auxiliary belts, with about 400 m of interbelt distance, are com-
posed of 2-3 rows of trees and 2 rows of shrubs. As a result, the rangeland has been
restored to sustainable use and the shelterbelts have supplied enough fiielwood for the
herdsmen.
In conclusion, the desertification in the ecologically fragile belt with rangeland-
cropland interlocked pattem can be reversed. To do so, anthropogenic pressures need
to be redistributed. Appropriate models need to be selected and the proper technical
measures adopted to increase the capacity of the land to sustain people and to improve
the environment and renewable resources in the whole region.
References
Liu Xinmin et al. 1994. A primary study on desertifícation dynamics and its reversion strategies in the
Middle Part of Horqin Sandy Land, China. In: Proceedings of the Japan-China Intemational Sympo-
sium on the Study of the Mechanism of Desertification (ed. Masami Ichikuni). Toyo Publishing and
Printing Co., Ltd, Tokyo.