【摘要】 绿洲是西部干旱区人类生存发展的基础,绿洲的形成、发展和演变一直是干旱区生态与地理研究的核心内容。本研究以位于新疆焉耆盆地库鲁克塔格山北麓、博斯腾湖南畔的库鲁克绿洲为案例,利用4期1973年~2005年期间的遥感影像数据,在斑块水平和景观水平上完整回溯了库鲁克绿洲早期形成、发展和演变的时空格局动态过程。通过空间分析表明,库鲁克绿洲发展演变过程和格局呈现出景观镶嵌斑块的"散布、扩展和融合"循环往复的节律性动态过程特征,不同斑块的规模由子斑块扩散速率、边缘扩展、斑块边界接触和融合过程决定。斑块镶嵌格局的时空节律变化导致了聚集斑块的等级镶嵌结构和动态格局。研究结果可为今后干旱区绿洲形成、发展和演变过程的时空动态预测模拟、管理规划与环境保护等提供了基本理论依据。更多还原

【Abstract】 Landscape analysis based on remote sensing technique allows precise dynamics quantification of the oases in arid land of western China. The spatial patterns of oasis expansion on the margin of fluvial fan in the north piedmont of the Kuruktag Mountains in Xinjiang Province between 1973 and 2005 are monitored and analyzed by using Landsat MSS/TM/ETM+ and CBERS2-CCD images. Based upon the human related factors and land use history, the development and evolution of Kuruk oasis can be categorized into four stages: initial invasion and establishment stage, dispersal stage, domination stage and succession stage. In the initial stage of the invasion, the shifting between pastoral nomadism and cultivation were intensively replaced by settled agricultural cultivation. Land degradation was closely related to the substantial increase in population, especially during the period from the 1900s to 1973, as well as the associated intensity of land use and abuse. In the dispersal stage (1973~1990), salt marsh and riparian forest were converted into oasis agriculture with favorable irrigation conditions. The oasis expansion entered into a period of slow development due to the surface water shortage. In the domination stage (1990~2000), the improved groundwater irrigation technologies triggered the rapid expansion and spread of artificial oases, which led to the abruptly increase in water demand. The shrubland of oasis-desert ecotone declined dramatically. With the development and expansion of the piedmont oases, the Kuruk oasis entered into the succession stage (2000~2005). Groundwater shortage became a bottleneck in the development of oases. The ephemeral lake area of Tsagan Sag Playa exhibited highly-frequent fluctuations and reduced continuously. Many factors are analyzed in this paper, including the growth velocity pattern of new oasis emergence patches, edges collision of patches, the oscillating frequencies of the gaps in the expansion of patches, the dynamic changes in patches and landscape matrix characterizing the expansion rate of oasis ecosystem. The results show that the development rate of irrigated oasis agriculture is greatly constrained by existing land and limited water resources. Conversions of desert shrub to oasis agriculture as well as uncontrolled groundwater pump continuously damage the already fragile arid ecosystem. Regularities in the spatio-temporal oscillation between the expansion and connection in the oasis growth are revealed, highlighting the important research findings in each stage. Oasis patch size is determined by the expanding rates of sub-patches, lateral expansion, collision and subsequent joint. When individual or isolated oasis patches are not very far from the core oasis, they continue to expand, resulting in a joint of the parent patches with the satellite patches. The joint stops or slows down significantly, leading to the landscape patterns of joined pieces through land reclamation and cultivation. The result can offer new insights and opportunities for oasis management and environment protection, provide information for future research into the spatio-temporal dynamic evolution of oasis, and further develop the existing oasis theory.更多还原