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

Abstract

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.

Sand burial compensates for the negative effects of erosion on the dune-building shrub Artemisia wudanica

“…Mean annual precipitation is 340 mm, 70% of September, respectively. In this region, overgrazing has led to a desertification of over 90% of the land, and consequently, active sand dunes, advancing at a rate of 5-7 m·year -1 , are widely distributed (Liu et al 2006;Ma and Liu 2008a). The active sand dune vegetation coverage is less than 5% and the plants are found at all parts of the active sand dune, i. e., windward slope, leeward slope and crest of the active sand dunes.…”

“…and A. wudanica, with a coverage less than 5%. Sand dune movement, wind erosion, and sand burial are frequent in this ecosystem (Yan et al 2005;Ma and Liu 2008a).…”

“…An important feature of active sand dune habitats is the alternation between wind erosion and sand burial (Petru and Menges 2004;Liu et al 2006;Ma and Liu 2008a). Some parabolic dunes are created under constant wind direction (Ardon et al 2009), but wind direction in many other regions is not constant and often varies by seasons., The exposed roots or rhizomes may be partly or entirely re-buried (Liu et al 2006;Ma and Liu 2008a), and buried roots or rhizomes could be exposed by erosion during the next wind event (Petru and Menges 2004).…”

“…Some parabolic dunes are created under constant wind direction (Ardon et al 2009), but wind direction in many other regions is not constant and often varies by seasons., The exposed roots or rhizomes may be partly or entirely re-buried (Liu et al 2006;Ma and Liu 2008a), and buried roots or rhizomes could be exposed by erosion during the next wind event (Petru and Menges 2004). Seedling tolerance to various degrees of sand burial or wind erosion has been widely studied (Zhang and Maun 1990;Danin 1996;Danin 1997;Gilbert and Ripley 2008;Li et al 2010a, b;Burylo et al 2011).…”

Aerial seed bank in Artemisia species: how it responds to sand mobility

“…Since seedlings emergent in the windy season are not likely to become established due to erosion or burial on an active dune (Li 1980), delay in seed release might function to postpone seed germination until near the end of the windy season, heightening the probability of seedling survival (Venable and Lawlor 1980). However, there have been only a few discussions on how aerial seed bank adapts to sand mobility (Liu et al 2006;Ma and Liu 2008).…”