农牧交错区沙地景观空间格局的间隙度分析

Lacunarity Analysis of the Spatial Patterns of Sandy Landscape in Agri Grazing Ecotone

科尔沁沙地农牧交错区典型景观空间格局的间隙度分析表明：放牧活动是造成该地区景观变化的主要原因，这一过程直接导致了半固定沙丘斑块（放牧场）在整个景观中的间隙度指数增高、面积减少；相反，半流动沙丘斑块间隙度降低，面积增大。农业生产活动对农田斑块的影响要小于牧业对半固定沙丘斑块的影响。同时研究结果还指出，尺度对空间格局的分析有较大的影响，对同一研究对象采用不同的尺度来研究，可确定两者间的相互关系。景观间隙度分析，可以为研究不同的生态学过程在景观中的扩散、转移提供必备的条件和依据。

Lacunarity has been used to analyze spatial patterns of Agri Grazing Ecotone which is a typical sandy landscape in Horqin region. Results show that grazing action induced landscape changes is a principal reason in the studied area; the lacunarity indices of semi fixed sand dune and shifting sand dune patches, which are directly affected by pasturing, vary significantly when grazing action came about from 1958 to 1981. But the alteration trends of lacunarity indices are different. For semi fixed sand dune patches, lacunarity index increased in above mentioned period, otherwise lacunarity index decreased meantime for the patches of shifting sand dune. The lacunarity indices of spatial patterns of the cropland patches have altered less than that of sand dune area, so we consider that grazing action made landscape change more dramatically than agricultural action in Horqin region. For elucidating different compositional patches of typical landscape in this area, we divide whole patches into three types to study different spatial patterns of sandy landscape by using the lacunarity analysis. The sandy pasture, which indicates the effect of grazing action, is the first type that includes the semi fixed sand dune and the shifting sand dune patches; the second is cropland patches that indicate the effect of agricultural regime; and the third is lake patches which indicate the integrated effect of agri grazing. Comparing the lacunarity variation of sandy pasture patches with the lacunarity variations of cropland and lake patches, the curve of sandy pasture patches is the most severe fluctuation among three types from 1958 to 1981, and that of lake patches is the least alteration. In addition, the investigation scales of both the space and time play a very important role in the lacunarity analysis. It not only affects research results but indicates the lacunarity variation trends which represents the patch contagion degree. Consequently lacunarity index can be used as a foundational matching factor for studying relationship between landscape patterns and ecological processes, especially for studying the patch patterns in temporal scale.