Abstract: Based on 22 species’ Important Value (IV) at 36 sampling sites in the Yellow River Delta National Natural Reserve (YRDNNR), using Two Way Indicator Species Analysis (TWINSPAN) method, this research categorized the plant communities in YRDNNR into 6 groups, Ass. Suaeda salsa, Ass. Tamarix chinensis-Suaeda salsa, Ass. Tamarix chinensis-Phragmites australis + Suaeda heteroptera, Ass. Phragmites australis, Ass. Salix matsudana-Phragmites australis, and plantation community. At the gradient of succession, the soil pH increased gradually, the soil salinity decreased, the soils containing the most and the least moisture appear in the Ass. Phragmites australis and plantation community respectively, the total organic carbon (TOC) and total nitrogen (TN) in the soils increased, and the ratio of carbon to nitrogen decreased. The key soil environmental factors detected by Canonical Corresponding Analysis (CCA) that influenced the distribution of plants in YRDNNR were soil salinity and pH. The plant species diversity had a significant negative correlation with soil salinity, but a positive correlation with soil pH. Investigation of niche using the formulae described by Levins and Pianka at soil pH and salinity gradients showed that the dominant plant species such as Tamarix chinensis, Phragmites australis, Suaeda salsa, had a wide niche breadth; the niche overlaps between species were relatively smaller, indicating that niche differentiated under soil pH and salinity gradients, which was an essential adaptation to the stresses of soil alkalinity and salinity in YRDNNR.

Key words: TWINSPAN, CCA, species diversity, soil variables, niche analysis, Yellow River Delta

摘要： 以黄河三角洲自然保护区36个样地22个植物种的重要值(IV)为基础, 使用双向指示种分析法(TWINSPAN)将其分为6个群落类型: 翅碱蓬群落、柽柳?翅碱蓬群落、柽柳?芦苇+碱蓬群落、芦苇群落、旱柳?芦苇群落、人工林群落(刺槐林和白腊林)。在群落演替梯度上, 土壤pH逐渐增加, 土壤盐分呈下降趋势, 土壤含水量最大和最小值分别出现在芦苇群落和人工林群落, 土壤有机碳和总氮总体逐渐增加, 土壤碳氮比呈下降趋势。通过典范对应分析(CCA)发现, 影响黄河三角洲植物种分布的关键土壤环境因子是土壤盐分和pH, 植物物种多样性与土壤盐分呈显著负相关, 与土壤pH有正相关关系。在土壤pH和盐分梯度上的生态 位分析发现, 优势种柽柳、芦苇和翅碱蓬的生态位宽度较大, 植物种之间的生态位重叠一般较小, 说明物种在土壤pH和盐分梯度上出现了生态位分化。

关键词: 双向指示种分析, 典范对应分析, 植物物种多样性, 土壤因子, 生态位分析, 黄河三角洲