毛乌素沙地羊柴种群点格局分析

在宁夏盐池毛乌素沙地,分别在固定沙地和半固定沙地设立一块50 m×50 m典型样地,应用Ripley’s K函数的双变量点格局分析方法,对飞播条件下羊柴种群的点格局进行研究。结果表明:羊柴种群的空间分布格局与植株大小及生境2种因素关系密切,随着羊柴植株形体的增大,其集聚强度加强;对于羊柴种群的空间关联性,随着2个大小级的形体大小差异减小,它们的空间正关联关系将加强;半固定沙地上的羊柴种群及其各大小级与固定沙地相比更趋向于集群分布,同时各大小级之间的空间正关联也更明显;移植羊柴时,应尽量将其栽种成集聚分布形式,以提高植被成活率。

Pointpattern analysis of Hedysarum laeve population in Mu Us sandy land

Hedysarum laeve is an important and widely planted sand fixation plant in north China arid region.Population pattern of this specie is studied with the method of point pattern analysis.Two 50m×50m typical sample plots with different aerieal seeding periods were selected as research sites in Mu Us sandy land,Ningxia Province.As to the analysis method,Ripley＇s K function bivariate point pattern was performed to find the space correlation between the plants.The results show that： space distribution pattern of Hedysarum laeve depends on two factors,individual sizes and environments.Along with the increase of plant size,Hedysarum laeve is more likely to follow clumped distribution.The spatial association between plants will turn from negative correlation to positive correlation if their size differences are diminished.Unlike the Hedysarum laeve plants growing in fixed sandy land,those plants in semi-fixed sandy land are easier to follow clumped distribution and associate with each other positively.If Hedysarum laeve plants are transplanted into shifting sandy land for sand control and vegetation restoration,they ought to be arranged in the form of clumped distribution rather than regular distribution.