Persistent soil seed bank in Agriophyllum squarrosum (Chenopodiaceae) in a deep sand profile: Variation along a transect of an active sand dune

摘要

Distribution of soil seed bank in a deep sand profile along a transect of an active sand dune has been rarely studied. Reports on the persistence of the seed bank of pioneering dune plants are also scarce. In mid-September of 2005, just before the new seed set, an investigation was therefore conducted to determine the magnitude of the persistent soil seed bank in the pioneering annual plant Agriophyllum squarrosum in a 1 m sand profile along a transect of an active sand dune. Horizontally, seeds on the middle and upper windward slope, and on the lower leeward slope were more abundant than those in other locations. On the leeward slope, the mean seed density increased from the upper to the lower slope, but on the windward slope a contrary trend was evident. Seeds tended to be vertically concentrated in the profile of 20-70 cm, and be buried deeper and deeper along the transect from the lower windward slope to the lower leeward slope. This study indicates that (1) the presence of a persistent seed bank is one of the mechanisms for the pioneering annual dune species to adapt to active dunes; (2) the soil seed bank pattern in the active dune at the end of the growing season differs from that at the beginning of the growing season; and (3) a shallow sand profile is not enough to elucidate soil seed bank pattern of active sand dunes.