【作者】 蒋勇军；

【导师】 袁道先；

【作者基本信息】 西南师范大学 ， 自然地理学， 2005， 博士

【摘要】 岩溶生态环境是一种象沙漠边缘地区一样脆弱的生态环境。近年来,我国岩溶地区由于人口迅速增加,人类活动对岩溶地区的影响强度日益增强,更加加剧了岩溶生态环境的脆弱性。土地利用是人类活动的集中体现,因此,土地利用的变化对岩溶区生态环境将产生深远的影响。 土地利用变化对生念环境的影响是国际上土地利用/土地覆被变化研究的重要内容。岩溶区土地退化的主要原因之一就是土地利用不合理,研究岩溶区土地利用变化对土壤质量变化的影响不仅能够为岩溶区土地资源的合理利用提供科学依据,而且有助于岩溶区生态环境的保护,促进社会、经济和环境的协调发展。 论文以中等空间度的云南省泸西县小江岩溶流域为研究单元,通过资料收集、野外调查和采样分析,运用地理信息系统、统计分析、地统计学模型和数学模型等方法,研究了流域20年来土地利用的时空变化特征及变化机制,从点、面相结合的角度研究了流域土壤质量的时空变化特征及变化机制,并对流域土地整理进行生态评价,为西南岩溶地区水土资源的合理利用提供理论基础。 通过解译航片和野外实地调查、填图分别获得小江流域1982和2003年土地利用图,在GIS的支持下,通过空间分析,并利用土地利用景观的多样性指数、优势度指数、均匀度指数、破碎度指数、分离度以及重心转移模型等对流域土地利用变化的空间格局进行定量分析,揭示了流域20年来土地利用的时空变化特征。(1)1982—2003年,小江流域610.12Km~2的土地利用发生了变化,占流域面积的59%;土地利用类型的变化主要表现为未利用地向耕地和林地的转化以及林地向耕地的转化,三者变化面积为475.29km~2,占流域土地利用变化面积的77.9%;(2)20年来流域土地利用动念变化十分迅速,综合土地利用变化动态度达2.95%,单一土地利用变化的动念度以园地和耕地最快,分别为34.09%和10.55%;(3)20年来流域土地利用空间格局发生很大变化,土地利用的斑块数量由1014个增加到1889个,增加86.3%,平均斑块面积由1.02 Km~2/个减少到0.55 Km~2/个,减少46.1%;流域土地利用空间格局的基本构型由以大斑块为主体、中—小型斑块镶嵌其中的构型转变为以中等斑块为主体、大—小型斑块镶嵌其中的构型;流域土地利用空间格局指数的破碎度指数增大了84.6%,多样性指数和均匀度指数增加了4.14%,而优势度指数降低1.6%;未利用地、林地的分离度指数分别增加了114.58%和69.64%,表现出分散分布趋势,而耕地的分离度指数减少45.86%,表现出集中分布趋势;20年来各种土地利用类型的重心向不同方更多还原

【Abstract】 The karst ecosystem is a very fragile one, which is susceptible to deterioration due to unreasonable human activities in karst area. The land use and land cover change play an important role in the deterioration of the karst ecosystem.Xiaojiang watershed of Yunnan Province, a typical karst watershed with medium size in scale, was chosen as basement to analyze the spatio-temporal variability of the land use and the soil quality, and the mechanisms of land use and the soil quality change. Based on the collection of historical data and sampling in the field, the author also made an ecological evaluation of land consolidation and rehabilitation, by using geostatistcs and GIS combined with mathematical model.Interpreting aerial photo taken at 1982 and mapping the land use through field investigations and survey in 2003, the land use maps of Xiaojiang watershed were obtained. Supported by GIS, and through analyzing the land use maps, the land use pattern change maps between 1982 and 2003 were obtained. The dynamic change in spatial pattern of land use and the driving force of land use change during the past two decades in Xiaojing watershed were analyzed. The results indicate: (1) The total land use transformed covers 610.12 km2, of which cultivated land increased by 268.5 km2 or 132.7%, but unused land decreased by 280.5 km2 or 54.36% during the past 20 years. (2) The land use change was very rapid in the past 20 years. The change speed of land use was 2.95%. Especially, the change speed of orchard land and cultivated land were 34.09% and 10.55% respectively. (3) The number of land use patchesincreased from 1014 to 1889, but the average area per patch decreased from 1.02 km2 to 0.55 km2. The spatial pattern of land use patches has changed from dominant large and scatter patches mosaic to dominant medium and scatter patches mosaic, and the types of dominating patch have also been transformed from unused land and forestland to cultivated land and forestland. (4) When the spatial pattern of land use was analyzed quantitatively by introducing the diversity index and fragmentation index, a clear picture of interference degree caused by human activities can be obtained. With the increased intensity of human activities, the diversity index increased by 4.14%, and the fragmentation index increased by 84.6%. Also, the isolation of the unused land and the forestland increased by 114.58%, and 69.64% respectively, but the isolation of cultivated land decreased by 45.86%. By analyzing the shift in the centers of unused land, forestland, or cultivated land, it was found that the spatial pattern of land use has changed dramatically during the past 20 years in Xiaojiang watershed. Centers of different land use types have changed towards different direction at different speeds. The distance in the shift of unused land center was farthest, which is 2.08 km, from northwest to southeast, and the distance in the center shift of forestland was 1.338 km from northeast to southwest, and the distance in the center shift of cultivated land was 0.222 km from southwest to northeast. (5) Through quantitative analysis by introducing social and economic data, it was clarified that the rapid growth of population and the economic development were the main driving forces of cultivated land change, and that the comparative economic benefit and the macro-policies such as ecological and environmental protection were important driving forces of forestland change in Xiaojiang watershed during the past 20 years. So the human driving force was direct factor of land use in the studied area.The new database of soil quality were established by laboratory analyzing of the samples collected in 2003 and by compared with data of 1982. Through application of Geostatistics combined with GIS, the spatio-temporal variability of the pH, organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium in soil in Xiaojiang watershed between 1982 and 2003 were analyzed. Results show that: (1) The pH, organic matter, total nitrogen, the total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium in soil in 1982 were 6.64, 33.3g/kg. 1.7g/kg. 1.7g/kg. 10.56g/kg, 114.98mg/kg, 10.68mg/kg, 66.04mg/kg, respectively; and those in 2003 were 6.74, 29g/kg, 1.6g/kg, 0.97g/kg, 11.05g/kg, 119.82mg/kg, 15.44mg/kg, 148.95mg/kg,respectively. Independent samples t-test of the tested indices of soil quality indicate that those indices have changed significantly during 20 years. (2) The parameters fitted by semivariogram models for of quality indices changed significantly in the past 20 years. (3) The spatial pattern of the soil quality indices changed significantly in the past 20 years in Xiaojiang watershed. The soil pH in 2003 was higher than that in 1982, and also the spatial pattern of the soil pH changed significantly, i, e., the soil pH increased in the east and southeast of the watershed, but decreased in the middle of the watershed. The content of the organic matter, total nitrogen and total phosphorus in 2003 was significantly lower than that in 1982, and also the spatial pattern of the soil organic matter, total nitrogen and total phosphorus changed significantly. The content of the soil organic matter decreased in the east, southeast and southwest of the watershed, but increased in the northeast and middle of the watershed. The content of the soil total nitrogen decreased in the east of watershed, but increased in the middle of watershed. The content of the soil total phosphorus decreased in the entire watershed. But the content of the total potassium, available nitrogen, available phosphorus and available potassium in soil in 2003 higher than that in 1982, and also the spatial pattern of those soil quality indices changed significantly. The content of the soil total potassium increased in the southwest and southeast of the watershed, but decreased in the middle of the watershed. The content of the soil available nitrogen increased in the middle of the watershed, but decreased in the southeast. The content of the soil available phosphorus increased in the middle and northeast of the watershed, but decreased in the southeast. The content of the soil available potassium increased in the middle, southwest and northeast of the watershed. (4) The increase of soil pH was mainly attributed to the transformation of the forestland and unused land into the cultivated land. The decrease of the content of the organic matter, total nitrogen and total phosphorus in soil was mainly attributed to the transformation of the forestland and unused land into the cultivated land, which enhanced water and soil erosion. The increase of the available nitrogen, available phosphorus and available potassium was mainly attributed to the use of more fertilizer.Through quantitative analysis by introducing relative soil quality index, it show that the soil quality decreased obviously in the past 20 years in Xiaojing watershed, but also the soil quality spatial pattern changed significantly. The total soil quality changed area covers 567.9 km2, of which the soil quality of 341.7 km2 decreased, but 226.2 km2 improved. The soil quality decreased in the southeast and southwest of the更多还原