Abstract: By using Two-Way Indicator Species Analysis (TWINSPAN) and Detrending Canonical Correspondence Analysis (DCCA), the type and structure of the plant communities in the Yellow River Delta were analyzed, with the distribution pattern of the communities and related affecting factors approached. The vegetations on 134 sampling plots were classified into 7 communities. Robinia pseucdoacacia, Imperata cylindrical, and Miscanthus saccharifleus communities were distributed on the areas with good soil nutrient condition and high ground water depth, Suaeda heteroptera and Aeluropus sinensis communities were on the areas with high soil salt content but low organic matter and total nitrogen contents and low ground water depth, Phragmites communis community was widely scattered on low-land areas, and Tamarix chinensis community occurred on the areas with high soil salt content and low ground water depth. The classification of the community types mainly reflected the variations of soil salt content and ground water depth, which were decided by microtopography. Among the factors affecting the distribution patterns of the plant communities, environmental factor accounted for 45.2% of the variation, spatial factor accounted for 11.8%, interactions between environmental and spatial factors accounted for 2.23%, and the undetermined factors due to biological and anthropogenic factors accounted for 40.8%.

Key words: Redundancy, Redundancy degree, Optimal growth redundancy degree, Agro-ecosystems management