| Yanchi County of Ningxia Hui Autonomous Region lies in the transition zone of arid and semiarid climates, and is a typical agriculture-animal husbandry ecotone. Due to the combined actions by nature as well as human beings, desertification that is characterized by being sandy has gradually and seriously threatened local economy development and ecology safety. For a better dynamic monitoring on desertification and a specific grasp of its state and internal mechanism, by using"3s"technology and landscape ecology theory, as well as the methods of statistic and building mathematical model, the paper analyzes and evaluates the dynamics of landscape and LUCC in Yanchi County over the past 20 years, and builds a quantitative estimating model of regional desertification degrees, and puts forward the concepts and design procedure of"integrative index of desertification degree", the paper also discusses the driving force of desertification in Yanchi County. Research results are as follows:⑴By international landscape ecology methods, the paper studies LUCC of Yanchi County since 1986. In terms of are changes, farmland increases year by year in middle 1990s and decreases after that, area of forest and civil construction increases gradually; discrete degree of plaques increases at the beginning and decreases at the end; there are two developing periods, 1986~1995 and 1995~2006, for landscape in perspectives of diversity, evenness, concentration class, and dispersion and juxtaposition index, in the latter period, it is higher in diversity, evenness, and dispersion and juxtaposition index than the former period, and concentration class is lower, which shows that in the latter period the distribution of different kinds of landscape is much more even, and the heterogeneity has increased.⑵Taking the database of interpreted remote sensing images, the paper analyzes and evaluates LUCC of the past 20 years, and forecasts future LUCC by Markov process model. The forecasting result shows, in the future development of Yanchi County, the percentage of construction land would steadily increase at a compared higher speed; the percentage of farmland would gradually decrease at a slow speed; the percentage of forest, grassland and non-utilized land would change less under the circumstances of the current policy and economy development; the percentage of water area would decrease year by year.⑶By methods of remote sensing combined with ground surveys, as well as the methods of ridge analysis, factor analysis, linear regression, the paper builds an estimating model of regional desertification degrees, and makes dynamic analyze and evaluation on desertification of different classes. The model can be expressed as: Ydesert = 4.186-0.0437Yc-0.00046Yb Where: Ydesert is desertification class, Yc is the mathematical estimated model of vegetation cover, Yb is the mathematical estimated model of biomass.⑷The paper puts forward the concept of regional IIODD, and specifies weighing of different desertification degrees in the whole desertification area by using analytic hierarchy process (AHP) based on scores given by experts. The weighing results of mild desertification, moderate desertification, severe desertification and extreme desertification are0.0553, 0.1775, 0.2622 and 0.5650, respectively.⑸Yanchi County is classified into different space and regional units by borders of towns, whose integrative index of desertification degree is extracted and analyzed by the paper, and the regional distribution discipline of the development of desertification is revealed: desertification degree decreases gradually on the whole from north to south in Yanchi County.(6) Driving forces of desertification: population is the most direct and the most important one, other ones are economy, technology, policy and culture.
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