准噶尔盆地南缘柽柳属植物种群及群落分布格局的分形特征

Fractal Dimension on Distribution Pattern of Tamarix spp Plant Populations and Communities in the South Margin of Gurbantunggut Basin

应用分形理论中的计盒维数,分别研究了准噶尔盆地南缘天然生长的柽柳属植物种群及群落的分布格局。结果表明,准噶尔盆地南缘不同类型柽柳种群与所有柽柳属植物种群构成的群落的分布格局,均具有明显的分形特征。以该研究区植物群落主要优势种多枝柽柳、刚毛柽柳、长穗柽柳和所有柽柳属植物群落为研究对象,分析了其计盒维数,它们的计盒维数分别为1.196、0.850、0.953和1.821;其值域为0<D<2。由此可见,在一定范围内分维值越大则其柽柳覆被愈复杂、愈不规则。除了所有柽柳属植物群落之外,其他任何柽柳种群的空间分布格局具有较低的计盒维数(均<1.2),表明了在干旱区荒漠带单类种群的空间占据能力较低,这与其所处极端环境有关。通过计盒维数分析,发现干旱区柽柳群落空间分布格局均具有统计自相似性,在不同的尺度范围内具有不同的空间分布格局。计盒维数定量地反映了准噶尔盆地南缘柽柳属植物种群及群落占据生态空间的能力,柽柳属植物种群及由这些种群所构成群落的空间占据能力依次为:柽柳群落(1.821)>多枝柽柳种群(1.196)>长穗柽柳种群(0.953)>刚毛柽柳种群(0.850)。

The fractal characteristics of distribution pattern of Tamarix spp plant populations and communities in the south margin of Gurbantunggut basin were studied by using the box dimension of fractal theory. The results showed that the distribution pattern of Tamarix spp plant populations and communities in the where represents obvious fractal characteristics; the box dimensions of Tamarix ramosissima population, Tamarix hispita population, Tamarix elongata population and Tamarix community were 1. 196, 0.850, 0.953 and 1. 821 respectively, and the theshold of fractal dimension is . Bigger fractal dimension value indicates that Tamarix spp plant populations and communities cover spatial distribution are more irregular and more complex. The studied results show that spatial distribution pattern of the communities exhibits statistical self-similarity with scale dependency, and different scale represents different spatial distribution pattern. Box-counting dimension of spatial distribution pattern quantifies the scale variation degree of Tamarix spp plant populations and communities occupying ecological space in the south margin of Gurbantunggut basin. The box dimension reflects the spatial occupation degree of the communities. Size down of spatial occupation capacity of Tamarix spp plant populations and communities： Tamarix community （ 1. 821 ） 〉 Tamarix ramosissima population（ 1. 196） 〉 Tamarix elongata population（0. 953 ） 〉 Tamarix hispita population （0.850）.