Spatiotemporal pattern of seed bank in the annual psammophyte Agriophyllum squarrosum Moq. (Chenopodiaceae) on the active sand dunes of northeastern Inner Mongolia, China

摘要

The seed banks of active sand dunes are critical for the adaptation of psammophytes to unstable habitats. However, existing reports have failed to effectively elucidate the spatiotemporal structure of these seed banks and the factors regulating them. The seed bank pattern of the annual psammophyte Agriophyllum squarrosum Moq. in active sand dunes was studied by taking into consideration the time, the depth of the soil profile, dune positions, and seed bank type (released seed bank, belowground and aboveground canopy seed banks). Most canopy-stored seeds were unburied before the following March of the maturation year; however, they were buried from March to May. The seed bank mainly comprised the aboveground canopy-stored seeds from September of the year of seed maturation to the following March. The seed bank was concentrated in the surface soil layers (0-10 cm) from March of the year following seed maturation to June and was concentrated in the deep soil layers (10-50 cm) after June. The seed bank in the lower leeward slope tended to be larger than those in the other dune positions. The canopy-stored seed:released seed ratio differed between dune positions. The findings of this study are: (1) sand burial and wind erosion play key roles in shaping the spatiotemporal pattern of the seed banks of active sand dunes, and (2) delayed seed release may be a major factor regulating the spatiotemporal pattern of the seed banks of certain psammophytes.