高寒草地狼毒与阴山扁蓿豆种群的空间格局

Spatial patterns of Stellera chamaejasme and Melilotoides ruthenicus var.inschanicus populations in alpine grassland

不同的格局类型和空间关联性可以反映出干扰状态下天然草地植物种群的资源环境适应对策。采用草地群落学调查与点格局分析方法,分析了祁连山北坡高寒草地优势种群更替过程中狼毒和阴山扁蓿豆种群的空间格局及其种间关联关系。结果表明:随着草地退化程度加剧,狼毒种群地上生物量、密度、植株高度持续增加,空间分布类型由聚集分布转变为非聚集分布,阴山扁蓿豆种群高度逐渐降低,种群密度和地上生物量先增大后减小,空间分布类型由均匀或聚集分布转为随机分布;狼毒和阴山扁蓿豆的空间关联性由显著正关联区间不断增大转为关联性不显著。草地退化过程中群落上层禾草西北针茅种群的衰退以及狼毒和阴山扁蓿豆的植株高度差异,导致了植物对光资源的非对称性竞争,使二者的资源分配策略发生了调整,并影响了空间分布格局和种间关联性。

Different types of spatial pattern and spatial association of plant populations can reflect their adaptive strategies in using environmental resources, and can reveal the population biology under disturbances. By using point pattern analysis, this paper studied the spatial pattern and spatial association of Stellera chamaejasme and Melilotoides ruthenicus vat. inschanicus at their different succession stages on the northern slope of Qilian Mountains, Northwest China. With the degradation of natural grassland, the plant density, plant height, and aboveground biomass of S. chamaejasme population had a persistent increase, the spatial pattern transferred from aggrega- tire into random or regular. In the meantime, the plant height of M. ruthenicus var. inschanicus population decreased gradually, its plant density and aboveground biomass decreased after an ini- tial increase, and the spatial pattern transferred from aggregative or regular to random. The spa- tial association between S. chamaejasme and M. ruthenicus vat. inschanicus populations trans- ferred from increasingly positive to not significant. During the degradation of natural grassland, the decline of Stipa krylovii population at the upper layer of the community and the differences in the plant height between S. chamaejasme and M. ruthenicus var. inschanicus made an asymmetric competition of light resources, which led to the regulation of the resource allocation strategies of S. chamaejasme and M. ruthenicus var. inschanicus, and affected the spatial pattern and spatial association of the two plants.