| During the past century, the population grow rapidly, then the demand of food grow accordingly. At the same time, the degraded global land resource and eco-environment, due to unreasonable use of land, has threatened the security of foodstuff, the societal sustainable development and the mankind living environment. The land degradation has attracted attention of the worldwide scientist on the agrology, agriculture and environment. In recent years, land degradation researched on a wide range is controlled actively, but the overall trend is still worsening. Assessment of land degradation is basic work in the planning of the territory renovation and the scientific control of land degradation.For a long time the technical means in assessment of land degradation by 3S is singleness, mainly by supervised and unsupervised classification to decide the class and grade of the land degradation, or by integrated assessment based on the weighted indexes by RS and GIS. But there is little research on using multi-source remote sensing data. Therefore, it is necessary to make comprehensive use of various theories and methods and adopt multi-source remote sensing data and non-remote sensing data. The monitor and assessment of the land degradation were in the dynamic study from multi-time, multi-space and multi-scale.Zhenlai county lies in Ecotone between Agriculture and Animal Husbandry in Northeastern China, where the environmental problems become more and more severe with the development of population, society, economy and aridity of climate in recent years. Zhenlai county is the typical area of land degradation in western Jilin province. Therefore, there is a urgent task to study on regional situation of land degradation and analyze the reason for changing, aiming at resolving the problems caused deteriorating environmental quality and serious land degradation.At first, the paper indicate the characteristic and rule of the change of land use in 1989,1996,2000 and 2004 in the research of land use/land cover, which provided rich microcosmic and quantitative information for eco-environment research. Secondly, the diagnostic index reflecting the eco-environment changes were inversed by using TM data. On this basis, the multi-target land degradation evaluation system was established with vegetation coverage, NDVI, surface temperature and surface albedo. Then assessment of land degradation in Zhenlai during 1989 to 2004 was taken by applying decision tree classifier. The result was used to forecast the tend of land degradation in 2019 and 2034 by markov model. Through researches on major eco-environment problems in Zhenlai county, the author analyzed the eco-environmental change process. The cause, speed and character of environmental degradation were revealed, and the eco-environment development trend was forecasted. All this had great significance for management and restoration of degraded lands, protection and construction of regional ecological environment and achievement in region sustainable development.The studies have shown that the main landtype of Zhenlai appears"two increases and three decrease"in quantity."two increase"means cultivated land and salt and alkaline land increase,"three decrease"means the area of meadow, water and wetland decrease rapidly, which indicate that the land use in Zhenlai county is unreasonable. Analyzing from space pattern, landscape diversity has changed a little, and dominance is increasing gradually, which indicate the difference of each landtype increase. The result shows that the increasing dominance is due to the increase of cultivated land and salt and alkaline land. Meanwhile, the trend of brokenness degree of paddy field and salt and alkaline land was increasing, and the trend of isolation was decreasing. This is related to land use by mankind and the natural factors.The study shows that there is a little area of high albedo and higher albedo in 1989 Zhenlai County, but area of lower albedo is most. Then the continual increase of area of high albedo and higher albedo indicate the ecological environment deteriorates by degrees and the area of degradation is increasing. The area of low vegetation coverage and lower vegetation coverage is mostly in the west of Zhenlai county, which landed large area of salt and alkaline land, sand land and degraded grass land. The surface temperature in Zhenlai from 1989 to 2004 changed flexuously. The lower surface(283-288 degrees) temperature changed like"", which is opposite to the middle surface temperature(288-293 degrees). And the low surface temperature(<283 degrees) and high surface temperature(> 298 degrees) decreased at first, then increased, which is opposite to the higher surface temperature(293-298 degrees).According to the weather data, there is relationship between the change of surface temperature and rainfall at the same year. The results showed that the area of the highest and high degradation has increased and the extent of degradstion has aggravated in 15 years, with salt and alkaline land increased quickly. Totally, the degree of land degradation has deteriorated in Zhenlai county from 1989 to 2004.Based on land degradation interpretation in 1989 and 2004, the Markov Model was used to forecast degradation tendency in Zhenlai county. The result indicated that area of the highest degradation will increase until 2034, and the area of undegradation will increase too. On the whole, area of the highest will increase and the rest will tend to evenness.The reason caused land degradation and ecological environment deterioration was either natural factors or human factors. The natural actors were foundation, while human factors were inducement and primary.To control the expansion of land degradation, people must take some countermeasures, such as population growth controlling, tradition agriculture cultivation and water used custom changing as well as saline alkali land treatment and improvement.The features and innovations of the thesis were that the grade of the assessment index by applying remote sensing data in four years classified, which is the basis for assessment by using decision tree classifier, and that evaluation system was constituted with four parameters includes vegetation coverage, NDVI, surface temperature and surface albedo, which is quantitative remote sensing inversed by TM data. By analyzing these environmental parameters, the rules and characteristics of the eco-environment in Zhenlai county from 1989 to 2004 was detected. |
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