Abstract:

Soil seed bank is a potential vegetation, which has an important impact on the stability of regional ecosystems and the structure and function of future vegetation. In this study, four ecological regions, Naiman, Shapotou, Minqin and Dunhuang, were selected to study the effects of sand dune location, sand type, vegetation, and soil depth on Agriophyllum. squarrosum soil seed bank. The results of this study indicated that the soil seed bank density of mobile sand dune in Minqin is the highest, with an average density of 51 grain /m², which are 2 times, 4 times, and 3 times that of Naiman, Shapotou, and Dunhuang; There are significant differences in the A. squarrosum seed bank in different parts of the mobile sand dunes; The seed bank of A. squarrosum mainly distributed in the middle of the windward slope and the foot of the leeward slope of the sand dunes, and scattered at the top of the dune and the leeward slope. The seed bank at the top of the dune only accounts for 28% of the middle windward slope, and the middle leeward slope only accounts for 30% of the leeward slope foot. The soil seed bank of A. squarrosum was mainly exists in the soil layer above 60 cm, the seed of 0-20 cm near the surface accounts for above 50% of the total seed quantity. With the dune fixation process, the density of soil seed bank is decreasing. The density of soil seed in mobile sand can reach 401 grain·m^-2, and it will decrease or even disappear completely in fixed sand; The total density of the soil seed bank of 0-15 cm in the community formed by A. squarrosum and C. arborescens was 800 grain·m^-2, which was twice that of A. squarrosum, 2 times of N. tangutorum + A. squarrosum, 6 times of H. ammodendron + A. squarrosum community; There was a significant linear relationship between A. squarrosum soil seed bank and the above-ground population. The soil seed density increased with the increase of the above-ground population density. Obviously, the soil seed bank and its distribution are important guarantees for A. squarrosum to adapt to severe wind and sand environment, and an important guarantee for self-reproduction，it was affected by various factors such as regional environment, above-ground changes, land type, soil depth, etc. In order to protect the desertified land, it is necessary to prohibit the harvesting of the resources on the sand land to supplement the soil seed bank of sand land.

Key words: soil seed bank, seed distribution, position on sand dune, vegetation type, Agriophyllum squarrosum