基于景观连接度的斑块分级的尺度效应

The scale effects of patches prioritization based on the landscape connectivity

认识到尺度对景观格局分析结果的影响,生态学家们越来越多地进行尺度效应的相关研究。已有的尺度效应研究多注重描述景观格局指数对尺度变化的响应,这只能对景观的状态进行描述,无法辨别那些对景观功能具有重要意义的关键景观元素。文章选取8个景观连接度指数,通过改变最小制图单元和物种的搜索范围,研究尺度对斑块分等定级的影响,并据此确定各连接度指数的尺度敏感性。结果表明:景观中斑块的相对重要性随尺度变化而变化,其变化程度因指数而异。其中,AWF为尺度效应最不明显的指数,PC和IIC次之,其余指数(NL,NC,LCP,H和F)的尺度效应均十分显著;在衡量景观的连通性时,除IIC外的其他所有指数的尺度效应均十分显著。由此说明,根据连接度指数确定的斑块相对重要性的尺度敏感性与该指数本身的尺度敏感性无关。

Recognizing the effects of the spatial scale on landscape pattern analysis, the ecologists have conducted more and more researches related to scale effect. Nevertheless, previous studies have just focused on describing the reactions of different landscape metrics to the scale variation, which could only describe the state of the landscape and not be able to identify those critical landscape elements for eco-function. In this paper, 8 connectivity indices were selected to examine the effects of scale on the identification of patches prioritization by changing the minimum mapping unit and dispersal distance of the animals, and then the scale sensitivity of all the connectivity metrics were determined. The results showed that the relative importance of patches in landscape was scale-dependent, and the responses to scale change were different for various metrics. AWF was the most robust metric, closely followed by PC and IIC, and the others （NL, NC, LCP, H and F） were strongly scale-dependent. For the measure of the whole landscape connectivity, all of the indices, except IIC, were strongly scale-dependent. So it could be concluded that the scale sensitivity of patches prioritization which was decided by connectivity indices had nothing to do with the scale sensitivity of these indices themselves.