科尔沁沙地土地沙漠化与景观结构变化的关系分析

从时空尺度分析了科尔沁沙地典型地区1975—2005年景观结构的动态变化对土地沙漠化的影响,结果表明:沙漠化程度在1975—2005年之间呈典型的抛物线变化趋势,其中在1985年达到最大值0.398；30 a来,景观尺度上的斑块密度由21个\5hm-2增加到52个\5hm-2,分维数由1.203增大到1.244,说明景观破碎化增强,结构趋向复杂、稳定；景观结构动态对沙漠化程度的影响分析表明,景观的多样化,促进沙漠化的正向发展；斑块密度越大,沙漠化程度越大,说明高的景观的破碎化程度和空间异质性对沙漠化过程对有促进作用。分维数对沙漠化过程的影响较为复杂,在2005年,分维数对沙漠化程度影响是正相关的,且有显著的线性回归关系,但在其他时间段上分维数对沙漠化的程度是负相关的,相关性不够显著。

Analysis of Relationship between Desertification and Landscape Structure Changes in Horqin Sandland

This paper formulated the ecological effect of landscape structure during desertification process of typical area at spatial and temporal scales in Horqin Sandland. The results showed that the trend of desertification process presented typical parabola from 1975 to 2005. The desertification degree index reached the climax as 0.398 in 1985. In the past 30 years, the patch density of mobile sand increased from 21 hm-2 to 52 hm-2; the fractal dimension also increased from 1.203 to 1.224. The results also indicated that the average areas of landscape types decreased whereas the patch density increased gradually, and the landscape fractal dimension index rose. Analysis of relationship between the landscape structure and the desertification process indicated that the higher landscape diversity indices and patch density were, the higher desertification degree was, which also illustrated that the higher landscape fragmentation and spatial heterogeneity promoted desertification progress. There was a distinctly positive correlation between the fractal dimension and desertification degree in 2005. However, during other periods, negative correlations were showed with insignificant relativity. The landscape diversity index, contagion index and fractal dimension index affected more on the desertification process in the past 30 years.