| Human have been changing the land environment with an unprecedented speed, extend and spatial scale and global changes concomitantly have been one of the most active studying domains all over the world in recent years. Ecological safety problems not only have been concerned by international society in 21s' century but also become the most critical task of sustainable development at present. The Three Gorges Reservoir Area (TGRA) lies in the jugular region of Yangtze River and is an important eco-economic fragile area. Because of its natural and socio-economic conditions and its special strategic station, TGRA has been regarded as a studying hotspot of sustainable development and environmental change. Primary studies show that a part of the eco-systematic functions are improving but degenerating as a whole and Land-Use and Land-Cover Change (LUCC) caused by human actions are the direct reason for eco-systematic degeneration.The author takes TGRA for studying object and analyze the mechanism of effect on eco-systematic safety caused by land-use change from four aspects, finally puts forward the lowest safe criterion for sustainable use of land eco-system and adjusts the structure of LUCC restricted by the lowest safe criterion. It ensures not only the lowest safe needs of eco-system but also the stability of socio-economic development and serves the sustainable use of land in TGRA.1 Analysis of space-time change of land-use in TGRAApplying RS and GIS techniques to carry through the man-machine alternative to translate the satellitic images of TGRA, the author distills space-time information of land-use change in two different periods in TGRA and analyzes them. As a result, cropland always tends to decrease while constructive-land constantly extends. Furthermore, the constructive-land increasing rate is 2.4 times after 1995 than before 1995. Forestland increases first and decreases afterward while grassland tends to decrease first and increase afterward from time of view. At the same time, great changes of the land types mainly take place in cities, riversides and some mountainous areas from space of view. Then, the author calculates the driving index of land-use change with macro-analysis model of land-use change, combining some socio-natural indexes. It turns out that eco-safety and survival economic welfare drive the land-use change.2 Analysis of ecological niche of land-use in TGRALand-use change has become the most active and common phenomenon in current eco-society and is a self-organized behavior of conversion from low niche level to high level. Under the control and concordance with land-use economic niche in different levels, the sustainable use will beturned into reality. This article has an analysis of the converting models of land-use in TGRA from both the contrived control and natural succession. On the basis of niche theory and system boundary theory, in this paper the author applies the model of land-use economic niche to quantitatively analyzing the interactional intensities between different land-use types and the diversity of economic niche in different land-use modes in TGRA by spatial information techniques. The study shows that there is a different niche of non-agricultural land and agricultural land in TGRA, and agricultural niche tends to decent from 0.165 to 0.156 while non-agricultural niche ascents from 0.835 to 0.844 during 1997 to 2002. The ecological niche margin between agricultural land and non-agricultural land is big and economic development and urbanization process make the speed and intensities of constructive land engrossing agricultural land greater than before. At the same time, the author discusses the approach for the sustainable land use of agricultural land and non- agricultural land from the economic niche of view. An increase in economic niche of agricultural land mainly depends on land-use configurable adjustment but non-agricultural land primarily lies on changes of land-use intensities. Finally, the author has a discussion about the ecological mode... |
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