Study On Land Use/Land Cover Change And Ecologic Effects In Western Jilin Province

Land use and land cover change (LUCC) is the most significant aspect in the research field of globe changing. Affected by both of natural and artificial factors, the global LUCC and land resources quality varied continually. As a result, it demoted the quality of regional eco-environment and the function of regional ecological service system. The Western Jilin is a major part of fragile ecological zone in the north of China. With the climatic anomaly and human's irrational activity in the past decades, the potential of fragile ecological environment brought about some real environmental calamity such as land desertification, alkaline, grassland degeneration, lake atrophy, wetland land degeneration and so on. Therefore, it seriously restricted the coordinated development of the regional economy, society and ecological environment. So, the western Jilin where the zone has a typical feature of fragile ecological environment was selected as a case. The LUCC and its ecologic effects for regional scale, which is a hot issue in current research area of resources and ecological environment, were studied in this thesis. Firstly, the theories, methods and the latest advance of LUCC, landscape ecology, Emergy (economy–energy) and the ecological service system domestic and foreign were comprehensively summarized in the thesis. Then, the author had a thorough research on the methods for land degradation dynamic monitoring by employing the remote sensing and geo-information technique. The research results indicated that the saline-alkaline desertification in the western Jilin was expanding in area and intensifying in degree within 1989-2001. The area of saline-alkaline soil was 138.31 104 hm2 in 1989 to 166.85 104 hm2 in 2001. The ratio of serious saline-alkaline area is 10% in 1989 and it come up to about 35% in 2001. In addition, the author built up a LUCC spatial database, which included of year 1989,1996 and 2001, by means of reomote sensing and geographic information system. With that, and making use of some model and method, such as spatial analysis technique; atlas pattern and land use/land cover change model,the author further described and analyzed the research area's LUCC in both qualitative and quantitative ways. From the change of land use structure, the main feature of LUCC in western Jilin is "2 increase & 3 decrease". It is means the farmland and saline-alkaline land increased obviously, but the grassland, water area and wetland decreased. From the shift of the land type, the main shift ways are from grassland to unirrigated farmland, from water area to saline-alkaline land, from grassland to saline-alkaline land, from unirrigated farmland to paddy field, from wetland to paddy field, from unirrigated farmland to saline-alkaline land, and from wetland to saline-alkaline land. The increasing farmland accounts for 46.5% of total LUCC. The increasing saline-alkaline land accounts for 38% of total LUCC. From the result of LUCC model analysis, the shift type of LUCC display a two-direction shift situation, the LUCC there is in a status of imbalance. From the index of landscape pattern, the pattern of grassland, unirrigated farmland and wetland appeared a distinct fragmentized trend, due to the influence of human activity and the deterioration of ecological environment. Emergy analysis, presented by Odum H. T., is a new method to evaluate natural an ecosystem services. With the unified unit, it can brings the value of nature resources into evaluation of environmental economic system, solves the problem of resources services on economic progress that traditional methods could not measure, and evaluate the sustainable development ability of ecological-economic system thoroughly. In this thesis, an emergy analysis of the Western Jilin agroecological system was presented. The total emergy used for Western Jilin agriculture had increased from 7.25×1021sej in 1985 to 11.1×1021sej in 2001. Free environmental resource emergy accounts for 13.2% ~28.5% of the total emergy use driving Western agricultural system,applied energy from industry accounts for 39.1%~63.2%,applied organic fertilizers emergy accounts for 21.6%~29.9%, nonrenewable environmental resource emergy accounts for 2.0%~3.7%. During the past decade there have been remarkable increases in Western Jilin agriculture fossil-fuel energy for machinery, fertilizers, and pesticides. However, the organic energy has long been an important source for agriculture production in Western Jilin. For the organic energy, the major inputs were from human labour and animal work. The organic emergy use was estimated from 2.11×1021sej~2.40×1021sej, accounting for above 50% of the total renewable emergy inputs, which plays an important role in Western Jilin agriculture for its sustainability. However, nonrenewable fossil energy used in Chinese agriculture is now much more than organic energy,especially including inputs of commercial fertilizers and pesticides. Some indices were also adopted to evaluate the regional agricultural environment resource basis, production power and its sustainable development ability from 1985 to 2001. The results show that Environmental Loading Ratio (ELR) of Western Jilin agroecological system had undulately increased from 3.07 in 1989 to 5.60 in 2001, which indicates that the agroecological system had been suffering a huge pressure.The Emergy Sustainable Index (ESI) had appreciably declined from 0.26 in 1989 to 0.19 in 2001, which indicated that the development of agroecological system was placed in an unstable and unsustainable status. It is because there were no sufficient investment of science technology and funds, no enough awareness of the importance for the agroecological system in Western Jilin Province.