| Desertification is one of the most serious global eco-enviromental problems, desertification has resulted in environmental deterioration and poverty, and tops the list of the ten problems facing enviroment and development. China is one of the most desertification-endangered countries in the world, with an annual economic loss of 54,000,000,000 RMB to desertification. So the study of it is of great significance to China. Located at the western frontier of China, Xinjiang is the province with largest and most widely spread deserted land. In the past ten decades, a series of eco-environmental problems caused by human activity like over cultivation has greatly constrained the expliotaion and utilization of resources and therefore become a main obstacle to the development of local economy. In the dissertation, the writer analyzes systematically the regional features, dynamic features, monitoring index, and driving factors of the desertification in Xinjiang by employing RS and GIS, and therefore provides some evidences for the prevention and control of desertification in Xinjiang.1. Based on the former study of desertification, the dissertation further analyzes the connotation and denotation of the definition of desertification through contrast, summary in a systematic way and simple words. And also the similar definitions are compared and contrasted and lay a theoretical foundation and provide some theoretical evidence for the defining and the categorization of different levels of desertification and the determination of driving factors.2. Based on a rather long temporal series of remote sensing data, employing RS and GIS as its tool and FVC that is of rather high sensitivity over the coverage of vegetation in arid area as its monitoring index of desertification, the dissertation analyzes the features of the dynamitic variation of desertification in Xinjiang over the years by using the slop variation to reflect the features of temporal-spatial distributing and the changes of areas of the desertification in Xinjiang.3. By overlapping the charting of land desertification and the types of vegetation, the writer analyzes the relation between the two and reaches a conclusion that desertification occurs more often in plain low grassland cover and mountain low grassland cover. The two kinds of vegetation are more likely to become naked grand and therefore are likely to be ruined by natural or human activity. They are frequent occurrence areas of desertification and a weak chain of the vegetation in arid area.4. By overlapping the charting of land desertification and the types of soil, the writer concludes that desertification is common to semi- hydromorphic soil and desert soil. And the reversion of alkaline soil shows the achievements of improvement of quality of alkaline soil.5. Based of the meteorologic data of the 45 years from 1960 to 2004,from the perspective of temporal series analysis, the dissertation analyzes the features of climate variation, and its influence over the desertification of Xinjiang as well as the natural driving factors of it. The result shows that the precipitation increased in recent 45 years and which will bring good effects for entironment, the vegetation will look up and desertation expand contrandictorily. The temprature is getting warming, which will bring bad effects for entironment, desertification expand. Dryness indexdroped, which can be considered the precipitation's change larger than tempriture's. That is, the variation of climate will do more good effects for entiroment than bad effects, do more positive driving than negative driving fordesertification. The asymmetric distributing of water and heat is one of the factors to make for desertification in Xinjiang.6. The dissertation modifies the model of Holdridge's indexes of lifezone according to the features of the ecological climate of Xinjiang. The influence of the variation of vegetation caused by the climate variation of Xinjiang in recent decades is also analyzed. In recent 40 years, the type of life zone hasn't changed, the area and number of patch changed only. The diversity changed but not too much..That is, diversity of life zone changed in little range, the whole entiroment is still be a rather stable state, whill be goo for desertation expand contrandictorily.7. Taking into the social and economic situation of Xinjiang into consideration, the writer, with experience in the study of the mechanism of the desertification of land in Xinjiang, shows the man-made driving factors of the desertification of land in Xinjiang. And also the fundamental reasons for it under the influence of the intervening of human activity.8. By using Arcmap, the writer figures out the statistics of Xinjiang form the 1km-Grid-Dis of China recourse and environment. And then the writer modifies the statistics by employing GPS to do the fieldwork and check. And some statistics are combined after topology is established. After all these works, a charting of land utilization of the 1980s and the 1990s are finished. Analyzing these statistics by the way of polygon fold and transfer matrix, the writer shows the influence of variation of land-use pattern over the desertification of land in Xinjiang in the 1980s and the 1990s and figures out the reaction between land-use pattern and the desertification of land in Xinjiang.9. From the perspective of the evolution of geomorphy, on the basis of dynamics, the writer establishes a mathematic model of the influence of human activity in the process of desertification and tries to quantity the influence of human activity in the process of desertification in northern and southern Xinjiang. The result shows that human effects occupy 66.55 percent while the natural factors occupy 33.45 percent during the desertification process in northern Xinjiang , 57.33 percent of human effects and 42.67 percent of the natural effects in southern Xinjiang. So, concludes that the influence of human factors is more influential than the natural factors. Due to the fact that the natural condition of southern Xinjiang is worse than that of the northern one and is more vulnerable to natural factors, the conclusion is made that the influence of human factors over the northern Xinjiang is more serious that that over the southern one.10. On the basis of the studies of the regional features of desertification of land in Xinjiang, the status quo of desertification and driving factors, in accordance with the regional characters of Xinjiang, the writers puts forward the counter measurement, restoration, reconstruction and improvement model of the desertification which is of the regional features of Xinjiang by employing the theory of eco-economic and systematic theories.
|
PDF Full Text Request