毛乌素沙地景观格局变化研究

摘要

通过对毛乌素沙地不同时期的景观分类和制图以及景观格局计算，分析了50年代到90年代毛乌素沙地景观动态与景观格局变化的特征和模式。研究表明，50年代以来，毛乌素沙地景观发生了巨大变化，流动沙地、半固定沙地面积大幅度增加，固定沙地面积迅速减少，农田面积明显增加，草原、柳湾和盐湿低地等面积显著减少。50年代时，整个景观以流动沙地和固定沙地占优势，而90年代，则以流动沙地占绝对优势。伴随着荒漠化的发展，各种景观要素类型之间相互转化，景观格局发生显著变化。固定沙地面积减少伴随着斑块的破碎化，大型斑块数量减少，小型斑块数量增加；流动沙地面积增加的同时，一方面，较小的斑块不断联合形成更多的大型斑块，另一方面，流动沙地不断向固定、半固定沙地内部渗透，形成更多的小型斑块，使整个景观更加破碎。不合理的人类活动是荒漠化扩展及景观格局发生显著变化的主要驱动因素。%Based on the landscape classification and cartography and the analyses of landscape patterns,the temporal and spatial patterns of landscape from the 1950s to the 1990s in the Mu Us Sandland,Northern China were investigated.The results show that since the 1950s the landscape in this area have undergone dramatic changes.The shifting and semi-fixed sandy land expanded rapidly and fixed sandy land reduced fast.The area of farmland increased and that of grassland,willow and wetlands salinized and/or damp decreased significantly.In the landscape,both of shifting and fixed sandy land had the largest proportion in the 1950s,and the shifting sandy land occupied the dominant position irreproachable in the 1990s.As a consequence of desertification development,a significant change appeared in landscape patterns.The decrease of area of fixed sandy land was followed by patch fragmentation,the decrease of number of big patches and the increase of number of small patches.Accompanied with the increase of area of shifting sandy land,small patches associated with others to produce more big patches;on the other hand,shifting sandy land invaded into fixed and semi-fixed sandy land to produce more small patches,so that the landscape was more fragmented.Irrational human activities seem to be the main driving forces for the desertification expansion and significant changes of landscape patterns.