Characteristics of soil seed bank of Caragana microphylla community under grazing and enclosure conditions in Horqin sandy land.

In this paper,the characteristics of soil seed bank of Caragana microphylla community under the grazing and enclosure conditions in Horqin Sandy Land,northeast Inner Mongolia,China were comparatively studied.The results are as follows:(1) The species of soil seed bank were dominated by the annual plants,and there was no significant difference in species richness between the grazed and fenced plots;(2) The seed density of soil seed bank in the grazing steppe was 3 475±519 seeds·m-2,it was 20 241±1 714 seeds·m-2 in the plots fenced for 6 years and 28 777±3 946 seeds·m-2 in the plots fenced for 12 years,and it was significantly higher in the fenced plots than that in the grazed plots;(3) The indexes of Shannon-Wiener and Simpson species diversity and Pielou evenness in the grazed plots were 1.36,0.68 and 0.56 respectively,and they were decreased with the increase of fenced time in the fenced plots;(4) Vertically,most seeds were found in topsoil of 0～2 cm in all plots,but the seed density of soil seed bank in all soil layers in fenced plots were significantly higher than that in the grazed plot;(5) The seeds were in an obvious aggregation distribution pattern in all plots,but the spatial heterogeneity of soil seed bank in the grazed plots was significant higher than that in the fenced plots.