Cao proposes a model to restore these grasslands, based on a three-dimensional design of herbaceous and ligneous plants, that can more fully utilize energy sources above-and below-ground. The model is based on the principle that livestock occupy less area, while each part of the system performs multiple functions. Forests surround and protect the pastures; a "shelterbelt network" reduces wind velocity, prevents wind erosion, diminishes evaporation, and eliminates damage caused by dry wind. Fodder shrub species can be used to stabilize the most volatile areas.

In one application of this model, 800 hectares of sand dunes have been enclosed. In an area of 267 hectares, 30 hectares have been planted in Pinus sylvestris var. mongolica and the rest in shrubs to stabilize mobile sands. Vegetation now covers 30% of this space. In 1983, 10,000 kg of hay and 4000 bunches of osier (wickers) were harvested. A fodder field of 33 hectares has been established within the windbreak. With such protection the ensilage maize harvest amounts to 75,000 kg per hectare, and the high-yielding fodder crop Astragalus adjurgens has reached 36,800 kg per hectare compared to conventional hay production of 1100–1500 kg per hectare.

Salinization Abatement Numerous advances have been made in controlling soil compaction and salinization in overgrazed rangelands of the northeastern meadow steppe region. Cao (1984) describes one approach tried by the Institute of Applied Ecology at the Wulanaodu Research Station. After noting treatments designed to modify the wind climate and vegetative cover in the area, Cao recommends soil remediation by plowing and harrowing. It must be noted that the soils in this area are poor in the main nutritive elements and must be replenished by fertilizers, especially in fodder fields. With regard to soil amendments, experiments to plow and harrow pastures with alkalinized soil, to apply powdered plaster to improve soil texture, and to add nutritive elements (ammonium sulfate, triple superphosphate, and zinc sulfate) to the soil have been carried out over an area of 10 hectares. According to Cao, these methods have increased hay yields by 70–100%.

Steppe Seeding and Restoration Li Yuchen (1990) of the Grasslands Station of Chifeng City, south of the Wulanaodu research area, presents a good example of "comprehensive treatment" of "sandification" in the West Liao River plain. Researchers in this area have developed tree and shrub windbreaks, fencing and to rotation-grazing systems, and aerial seeding of grasses, shrubs, and forbs.

Aeroseeding began in 1979 and by 1988 had been extended to 84,000 hectares. Test results indicate successful aeroseeding of grass and forbs on the gently sloping sandy land, with a vegetative cover rate of about 15% on "sandified" rangeland and abandoned uncultivated land. Two to three years after aeroseeding, the overall vegetative cover rate increased to 60–75%, and the highest rate to



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement