关键词: 黄河分洪区, 季节动态, 土壤种子库, 水淹干扰

Abstract: Taking seed germination test, this paper studied the seasonal dynamic variation of soil seed banks at April (spring), July(summer), October(autumn)  in 3 different sand dunes (fixed dune, semi-fixed dune, mobile dune) of the Yellow River diversion area; and analyzed the water-level-fluctuating zone (including the flooded, non-flooded and control areas) and the relationship between standing vegetation and soil seed bank. The results showed that: at flooded area, the density of soil seed bank declined gradually with time flowing i.e. April (201 seeds/m2)>July (176 seeds/m2)>October (170 seeds/m2). At non-flooded area, the density of soil seed bank was in the following order: April (1 063 seeds/m2)>October (1 036 seeds/m2)>July (733 seeds/m2). The figure of each month was bigger than that of the control area, and the same monthly variation rule was. The soil seed bank density was fixed dune>semi fixed dune>moving dune with distinguish monthly variation i.e. April (1 002 seeds/m2)>October (903 seeds/m2)>July (609 seeds/m2). There were 23 species belonging to 8 families and 23 genera in soil seed banks of the Yellow River diversion area. Most of them belonged to Chenopodiaceae and Poaceae, accounting for 65%. Judging from the lifestyle, each month took annual herbage species as principal. In terms of species composition, the number of soil seed banks in July was obviously smaller than that of April and October. At the non-flooded area, a microecological environment was formed by alternating wetness and dryness. It was more favorable for foreign species to enter. Thus, the species in soil seed bank were more abundant. Species in soil seed bank at hydro-fluctuation belt was more than that in the standing vegetation. However the control section was relatively small. Their Jaccard similarity coefficients of species composition between the seed bank and standing vegetation were respectively 0.357, 0.333 and 0.289 in flooded area, non-flooded area and the control area. The results indicated that the similarity coefficients were flat.

Key words: Yellow River diversion area, seasonal dynamics, soil seed bank, flooding disturbance