The construction of desertification-hazard system for revegetation

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1. The status of desertification and revegetation in the Mu-Us Sandy Land was studied on the 20 years changes of satellite images. GIS was constructed with this data thematic maps and governmental statistics. Field survey was conducted in the desertificated area or stable area, where we approached with the satellite data and GPS. Interview to local people was done, associated with vegetation and soil survey. The main factor of desertification was identified as over-grazing on the results of survey and the analysis of satellite data. Desertification was promoted when the animal density was more than 2 heads per 1 ha of grassland. High percentage of goat necessarily caused severe desertification. Inversely, revegetation was promoted in the surroundings of agricultural villages. Attention should be paid on the use of governmental data, since the statistics of breeding animals were reported excessively.2. The planning of revegetation was discussed with special reference to sustainable use of water resource, based on the analysis of water efficiency of plants using isotopic methodology. The water efficiency of Sabina vulgaris was higher than that of Artemisia ordosica, Caragana korshinskii and Salix matsudana. The consumption of groundwater should be suppressed by the use of such plants with high efficiency for water use. The water use of Salix matsudana was larger than Artemisia ordosica, and Caragana korshinskii, because the root system of this Salix was deeper than that of Artemisia and Caragana. Consequently, the conservative ability of shrubs should be higher than trees.