| - Land uses in the farming-grazing transitional zone (FGTZ) have been varying so quickly and drastically that their impacts on environment are profound. Studies on land use option in the scale of farming and grazing households can provide some scientific, deep gists with pertinence and maneuverability for regional development and environmental policymakings. The study is based on household data of spot check, investigated land use data on landform section, local domestic statistical data, meteorological observation data, land use data by remote sensing and conventional investigation. Methods of statistics analysis, yoss marginal analysis, geo-statistics analysis and methods of historical geography were employed in this study. Mechanism and environmental effects of land use option by farming and grazing households are studied from the aspects of ecological suitability, economic feasibility, and social acceptability. The results indicate that land use options for farming and grazing households in FGTZ are the integrated results by many factors such as ecological vulnerability, poverty,tremendous changes of communities and culture.At a long-term scale, the main driving forces to the land use option in the FGTZ are the immigrant pressures to this area and the tensile force from farming pressure, but the restriction of land use was caused by eco-environmental vulnerability. The interaction of these two forces were closely related to climate changes, peoples changes and population migration.The climate changes at different time scale are the foundation for the options of different land use types. The spatial and temporal coupling of precipitation, air temperature and strong wind result in severe wind erosion in spring and winter seasons and land degradation. And the production fluctuation caused by climate changes lead to local farmers to take some unwilling but practical measures such as harvesting a little with cultivating extensively, planting dispersedly and irrigating with wells, combining herbage meadows with woody ones, in the years when disaster happened increasing output of livestock which has become fully-grown and ready for slaughter and planting fast growing and early trees.There are some regularities, which can be found for the effects of the topography on different land use types. The amount of cultivated land decreased, in-order, from the bottomlands to the hills with soft covers, the hills with hard covers and sand lands, while the amount of grassland is in an opposite direction. The differences influenced by human activities become smaller. So, the pattern of three-circle land use is facing humanity obstacles. The different land use environmental effects are caused by the farming and grazing household to take different land use types according to the grasslands with different topographies.For the limited soil resources, we should improve the fertility by the way of reclaiming the lands with high fertility, green manure or burning the grass on waste land, reclaiming sandy lands, and increasing applications of fertilizers and manures. But the amendment of soil properties depending on the economy and technology are still facing the restriction of boundary effects.As the main bodies of land use option, the farmers and the herds should not only follow the rules for the ecological friendly changes, but regulate the land uses by people's demands and market development according to the economic laws.On the average, when cultivated land was converted to meadow and woodland, the gross profit for farmers or herds decreases notably, which is the inner driving force for the woodlands to be convertedinto meadow, meadow into cultivated land, and woodland into cultivated land. That changes of the economy profit for several primary crops were accompanied with the progress of structure adjustment indicated that the ecor.omy profit is the main driving force to the structure adjustment. And the economy profit of grassland varied greatly according to its type and quality, the low gross profit of...
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