| The variation characteristics of land use were analyzed with the ratio of contribution of changes (CCR), change intensity index, relative change rate and land use degree. In addition, the evaluation index system of land use eco-security was established by using conceptual model of"press-status-response"and the weight of evaluation indeices were made by Entropy method. The land use eco-security status in Lanzhou was evaluated from four different levels, e.g. index layer, factor layer, rule layer and target layer. And the correlation between land use degree and land use eco-security was analyzed, so as to give a way of the strategy on how to increase the land use safety level in Lanzhou. The research conclusions are as following:1. The variation characteristics of land use in Lanzhou(1) During the past 10 years, cultivated land, pasture and woodland played the significant role in land use structure changes in Lanzhou. And the great change of land use structure occurred in Xigu district, next Gaolan County, then Anning district, finally Yongdeng county. From 1997 to 2006, areas of those land use types changed greatly, CCR of those were above 21% and changes in intensity indicators of those were above 1.2. The relative change rate(R) of each type in Xigu district was all above 1, which was higher than the average value of that in Lanzhou. In Gaolan county, the relative change rate of cultivated land, pasture and woodland were higher than average value of that in Lanzhou, especially, the relative change rate of woodland reached 6.83. In Anning district, the relative change rate of woodland, grassland and residential and industrial land were higher than average value of that in Lanzhou, especially, the relative change rate of woodland reached 3.92, which followed Gaolan county. But in Yongdeng county, the relative change rates of all the types were lower than average value of that in Lanzhou.(2) During the past 10 years, the land use degree had an increasing tendency with a different level in all counties (districts) of Lanzhou except for Xigu district. Among of them, Anning district had maximum increasing amplitude which was 9.33%; next Qi Li-he and Chengguan districts which were 5.81% and 5.34%, respectively; the land use degree of honggu, gaolan, yongdeng and yuzhong counties increased slowly and their rates were less than 5%.2. Establishment of regional evaluation system of land use eco-securityCombined with social, economic, environmental conditions in Lanzhou, the evaluation index system of land use eco-security was established by using conceptual model of"press-status-response". The system includes index layer, factor layer, rule layer and target layer, which were picked to describe the Harmonious Development of society, economy and resources during the land planning and using.3. The characteristics of spatio-temporal changes of land use in Lanzhou(1) In Lanzhou, the level of land use eco-security was low and under an unsafe condition. Because of hypsography, hiemal climate and much aeolian sand, its entironment was feeble. In addition to, its unsubstantial economic base, behindhand productivity and extensive production led to exploit resources in excess. Meanwhile, its breakage speed was quicker than that of construction.(2) During the past 10 years, on the whole, the land use safety level had a positive tendency in Lanzhou. Its land use eco-security synthesis indicator was 0.6063 in 1997, which belonged to classâ…¢and means its ecological condition was sensitive. In 2006, the safety indicator was 0.6664, with 0.0601 higher than in 1997. But it still belonged to classâ…¢and sensitive condition. As such counties and districts, Chengguan, Yuzhong and Honggu districts had a higher increasing intensity, which were 25.03%, 18.09% and 17.65%, respectively; following were Chengguan and QiLi-he districts, with increasing intensity of 13.13% and 13.10%; other counties and districts had a low growth rate about 6%.4. The correlation between land use degree and land use eco-security indicators There was complex relationship between land use degree and land use eco-security index. The relationships between them in Chengguan and Anning districts were linear correlation. At the same time, the relationship achieved the most remarkable lever with r=0.977 in Anning district; it reached more remarkable lever with r=0.909 in Chengguan district; while in Qi Li-he, Xigu and Honggu districts, the correlations were quadratic polynomial with parabola trend line was down, and their average value was above 0.8 which means good relativity. In Yongdeng, Gaolan and Yuzhong counties, the trend line were the same as Qi Li-he, Xigu and Honggu districts, but they had a down parabola trend line and the relativity was common.5. The strategy on how to increase the land use safety level in Lanzhou(1) Control the population, improve population quality. The increasing population density as well as the decreasing of per capita cultivated land ends up to increasingly sharp conflict between population and foodstuff., and great pressure on the environment, further more, caused a vicious circle into the ecological environment of land. So the fertility policy must be strictly carrying out, decrease the birth rate, so as to make population and economy growth meet.(2) Promote circular economy and deduce consumption of natural resources.(3) To enhance the restoration and reconstruction for land ecology the ability to prevent soil and water loss shall be improved. In regard to eco-degradation area and sensitive area, it is suggested to theory and principles of Restoration Ecology and Ecological Engineering Technology to run the Conversion of Cropland to Forest and Grassland and restoration and reconstruction.(4) Increasing capital input in ecological land conservation, and ecological compensation mechanism should be established. Increase the input in ecological land conservation Out of the rural Tax-fee reform. System of use with compensation of land resources and ecological value of land be brought into Economic Calculations should be established.(5) Advance the ecological environment consciousness of the leaders all levels and the public, set up laws system of ecological land conservation, improve Maintenance and Management of Land Ecological Security.
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