LUCC And Emergy Evaluation On Sustainability Of Agricultural System In Arid And Semiarid Area Of Northwest China

Land use/land cover change affects the energy exchange, water cycle, soil erosion and accumulation, biogeochemical cycles and crop production such as land-based structure of the main ecological processes and functions. Especially for the direct dependence on land resources in the production of agricultural eco-economic complex systems, land use/land cover change impacts on system resources, energy input and output, therefore, complex system of agricultural production functions can have a great sustained and far-reaching impact. Therefore, land use/land cover change of the development of complex system of agricultural research should be continued. And LUCC research should be one of the main contents.Development of western region is a major strategic decision-making at the beginning of the new century in order to reach the great rejuvenation of China. It's very critical to achieve such a goal that land resources use and agricultural system are both sustainable on condition of better protecting ecological environment in arid and semi-arid area of northwest China.With the help of"3S"tecnology, ternary diagram and statistics etc., the analysis of LUCC and the evaluation on agricultural-system sustainability are processed taking Jinghe county of Xinjiang as a case study on the base of land resource science, landscape ecology, ecological economics, emergy theory, social-economic-natural complex system theory as theoretical framework and sustainable development theory. The information of LUCC in this dissertation is obtained from TM image of 1990, 1999 and 2007. With it the landscape patterns both land use and emergy distribution are spatially showed out. Acts on these objectives the core contents of thesis include:First, three TM remote sensing images act as the main source of information. Quantitative analysis of remote sensing methods combining Markov transition matrix is applied to comprehensive change research. The results focus on the change speed, the temporal-spatial transfer of status, the extent and trends of land use/land cover change and some indices of land cover:The farmland area increases then minishes gradually. From 1990 to 1999 its up speed is 13.75%/a. Land area of urban & rural construction is small in ratio. Its trend is going up at 18.15% per year from 1999 to 2007. And at the same time, the salty land & marsh is adding at more than 5%/a. However, grassland area decreases at a speed of 2.82% per year. Other types vary also, but their variable extents are not very obvious like farmland, urban and rural construction land and salty land & marsh.In landuse type transition, forest land, grassland and unused land are more obvious than others. There are all steady status in Markov transition with steps of 9-year, 8-year and 17-year. And their Markov-transition convergence closely relate to the step and initial state.From 1990 to 2007, the average NDVI of the studied area decrease with a degree higher than the landuse extent. It shows that the reducment of landuse extent can amplify the minishing NDVI, and human activities affect NDVI more and more greatly.Second, the emergy analysis is carried out on agricultural system. By means of the geostatistics module in geographic information systems, this thesis analyzes the emergy output of agricultural systems and the characteristics of the spatial distribution on it's correspond land-use types based on the classification results from TM remote sensing images.Starting from the emergy input and output in Jinghe County from 1990 to 2007, the key points are the evaluation on emergy sustainability of agricultural system. By cotrast, it is found that the tatal emergy input increase in fluctuation and the output ascend gradually. The intensive level continues to be improved. There is significant difference in spatial distribution of emergy output. And its high-value areas are mainly in the cotton and wolfberry plant field.From the emergy point of view, energy flow, material flow even information flow can all be transferred into solar energy uniformly to express. Then, some indices are inducted into evaluation on the sustainability of agricultural system. By means of the emergy evaluation results, four scenarios of agriculture development are analyzed on condition that a forecast method of artificial neural network (ANN) is choosed. They are natural development scenario, the largest ratio between input and output (EmY/ EmT) one, the maximum of marginal benefit (ΔEmY/ΔEmT) scenario and the adjustment on the ratio of 8% * EmT one. Furthermore, two indices S and D are induced into the analysis on stability of the agricultural system. Then, three general indices such as S/D, EYR and ESI are carefully analyzed. At last the most efficient one (EmR2+8EmF-8) that fits to the study area is selected out from them.Last, the results including both LUCC and emergy analysis on the agricultural system can help the sustainable development of agricultural system in Jinghe County and give some scientific basis to policy-making and stratigy-adjustment in rational use of land resources in the future.In Jinghe County it is proposed that the agricultural development in the future should learn advanced experience and successful practices on the development of sustainable agriculture or eco-agriculture from the domestic and abroad for the sustainable development of local agricultural use. Pay attention to the use of new energy and the advantages of local resources such as solar, wind, etc., improve the value of the use of renewable resources into the ratio of the agricultural systems. At the same time, we should be good at mining the resource potential of the local characteristics, such as cotton, Chinese wolfberry and artemia; based on advantage when the region to develop agriculture, forestry, animal husbandry and fishery together and grain farming, cotton, forestry, fruit, livestock, poultry , three-dimensional combination of aquaculture development.In the specific process of agricultural development, some countermeasures should be taken to improve its sustainability. The first one is to improve the farmer quality of all aspects; the second one is that lots of efforts should be spent on the agricultural water-saving for good efficicncy; the third one is to adjust the agricultural structure with the spirit of "one industry-based, diversified economy". And under the premise of basic industries in the stability of the original, insists on wolfberry plant, aquaculture operators and others such as the development of a variety of ways are nacessary. In order to ensure the effective implementation of response measures, all of the departments must actively coordinate and support the establishment of a security system for the sustainable development of agriculture in studied area. And then an excellent sample can be set for our whole northwest arid area with good agriculture development sustainability.