水淹干扰对松嫩草原三种禾草种群分布格局的影响

Influences of Flooding Disturbance on the Distribution Patterns of Three Grass Populations on the Songnen Steppe, Northeastern China

为探明1998年水灾对松嫩草原禾本科植物种群分布格局的影响,对不同水淹干扰梯度上的羊草、碱茅和野稗种群进行了格局分析和对比研究。结果表明:三种禾草主要表现为集聚型分布,水淹干扰对同一物种种群的分布格局类型影响不显著;水淹干扰通过促进土壤物质的水平交流,降低了土壤异质性,从而减小了靠种子繁殖的禾草(如碱茅、野稗)种群的分布格局强度;水淹干扰对靠地下根茎扩繁种群的羊草的分布格局规模影响甚微,对靠种子繁殖种群的禾草的分布格局规模有一定程度的影响;洪水对种子等繁殖体的二次散布作用对种子的分布产生影响,使得后续生长的种群更加趋于随机分布。

To investigate the influence of 1998 flood on the distribution pattern of grass populations on Songnen Steppe in Northeastern China, we conducted a comparative study along the flooding gradient on the distribution patterns of three grass species: Aneurolepidium chinense, Puccinellia chinampoensis , and Echinochloa crusgali. The results are as follows: the three species populations, in spite of the flooding, remain in congregated distribution patterns. Flooding facilitates the horizontal interflow of the soil substances, and smoothes out the soil differentiations, thus lessening the distribution pattern intensities of P.chinampoensis and E.crusgali , which depend mainly on seeding to propagate and regenerate. Flooding disturbance influences remotely the distribution patterns (including pattern style,pattern intensity and pattern scale) of A.chinense populations, which mainly depends on the vegetative propagation of rhizomes to regenerate, though does affect the distribution pattern scales of P.chinampoensis and E.crusgali populations. Flooding disturbance alters the suitability and competitiveness of the plants by modifying the soil environments, thus affecting their population densities, and modifying their population distribution patterns.