Study On Land Desertification And Eco-Environmental Evolvement In The Songnen Plain Abstract

Global changes and sustainable development had been the focus attention of the people all over the world at present. The eco-environment getting worse had been one of the important problems that must be faced by human being. Though dimensionality of our country was wide enough, the personal appropriation to the land resource was relatively less. In recent years, so short land resource was sharply decreased for the increasing of population and the unreasonably exploitation and utilization to it, and resulted in the aggravating loose of water and soil, land sandy, alkalization and desertification, which made the eco-environment worsen. So efficient technique measures must be adopted to orderly carry the eco-environment investigation and dynamic monitor to the land resource in time, and effective countermeasures should be put forward. Being bestriding Heilongjiang and Jilin province, the Songnen plain was the most important market grains and beans basement of China, it place an important pole in the construction of safe food supplies system of the country. As the increase of the population in the area, human activity strongly affected the land eco-environment day by day. Being influenced by the traditional custom and confined by the production condition, the coarse management fashion was followed that plane more but gain less, that was robbing production. Therefore, the land capacity generally decreased, the proportion of high produced field reduced, low produced field increased, the area of saline-alkali soil and sandy soil widen, land utilized structure maladjusted, the area of grassland lessen, and the eco-environment badly worsen, which fasten the widen of saline-alkali land and sandy land, made the problem of land desertification stand out. The factors above restricted the development of farming and stock raising. So there were important meanings to area development on agriculture and social economy that to strengthen the land renovation, to keep the worsen direction of eco-environment, and to get back and enhance the synthesis throughput. During the item research works, it was discovered that the complexity and ponderance of the eco-environment problems in the Songnen plain. It was difficult to study on it more accurate through one subject, single technique, or the same measure. So it was needed that the intercross and penetration among subjects and the amalgamation and integration from different techniques to study complex eco-environment problem. Aiming at the land desertification and the eco-environment problems, it was used in the thesis that the theory integrated among different subjects, technique integrated of RS-GIS-GPS-EIS, and multi-sources RS or non-RS data. And the dynamic study was done on land desertification and eco-environment in the Songnen plain from different time, allaround space, and various scales. Using the space analysis function of GIS, space data were widely dug out and picked up. Adopt the land utilization models of space shape and dynamic exchanges, abundant microcosmic and ration information was offered to the eco-environment study. Contraposing to the main eco-environmental and desertification problems, using MODIS data, the states of vegetation cover and desertification were monitored and studied, vegetation index figure and desertification classified figure was done, then they were stacked with desertification classified figure and numerical attitude figure under the space analysis function of GIS. It was found that the desertification of the Songnen plain was mainly in the hinterland of it, that was it mostly distributed in the hinterland of southwest plain with the attitude of lower than 200m. The area of desertification in the hinterland occupied more than 64% of that in the whole area, in which serious one occupied more than 95% to the whole area. The land quality in the east of the Songnen plain was relatively high, and vegetation cover was better. Whereas most of the desertification in the Songnen plain is alkaline one, TM data was using on alkalization in the hinterland of the Songnen plain to do dynamic monitor and stacking in various periods of time. It was analysis that the rules of taking place, developing and distributing. Study showed that saline-alkalisoil was mainly distributed in such physiognomies as the lower plain, low terrace along rivers, and lacustrine plain, and so on. From 1989 to 2001, the development of saline-alkali soil in the hinterland could be divided into two periods, in one of which, that was seven years from 1989 to 1996, the area of saline-alkali soil outspreaded obviously while the degree of it was not sharpen in evidence, in the other of which, that was five years from 1996 to 2001, the area widen a bit, and more extruded was the aggravation of the alkalization degree, which was incarnated on the enhance of the proportion of heavy saline-alkali soil to the total saline-alkali one. Land use and land cover is the most extruded sight sign in the surface layer on earth, its changes were the result of both nature condition and human activity, it showed the influence of human to the eco-environment. At first, RS-GIS integration technique was using in the thesis to land use RS dispelling from 1989 to 2001 in northern Jilin province, the dynamic changes of the land use state were taken as a masterstroke to the study on eco-environment, using the changes of number, the space model and the dynamic exchange of land use style, it was studied that the time and space evolvement course of land use in northern Jilin of the Songnen plain, which indicated the leading direction, character and rules of the changes progress, and it was the basement of the study on eco-environment evolvement. Based on the analysis of the land use styles number model, it was concluded that the land use style changes mainly incarnated in the phenomenon of "two increases and three decreases". Two increases meant the increase of the area of infield and saline-alkali soil. Three decreases meant the decrease of the area of grassland, water area and marsh. Land use space dynamic model indicated the change rules of the space shape of various land patches, which showed that the crushing degree of such land styles of infield, woodland and saline-alkali soil decreased, and the shape of the boundary was simplified and regularized, going centralizing and becoming blocks, while the crushing degree of grassland, water area and marsh increased, and the shape of the boundary was going complicated, irregular and separated. The exchange model indicated the exchange direction and number among the land use styles in northern Jilin province. It showed that the...