Field survey and laboratory experiment were conducted to study the characteristics of soil seed bank for the grassland in a typical prairie on the Loess Plateau

such as species composition

density

spatial and temporal pattern distribution

and diversity.Results showed that there were 37 species in the seed bank

which belongs to 11 families.For the species of seed bank

Gramineae

Compositea

Labiatae

Leguminosae

and Panunculaceae were dominant.From green up stage to withering stage

the percentage of Leguminosae

Gramineae

and Violaceae decreased and however

the percentage of Compositea and Labiatae increased greatly.Density of soil seed bank increased significantly.For the vertical distribution

the number of seeds took on a decreasing trend with soil depth increasing.In terms of the level distribution of soil seed bank

landforms were in the descendant order of fenced grassland and grazed grassland;lunar slope and solar slope;and top slope

middle slope

and bottom slope.Results from the study indicated that the Margalef and the Shannon—Wiener diversity indexes of soil seed bank were higher in the enclosed grassland

and Pielou evenness index was higher in the grazed grassland.They all decreased from green up stage to withering stage.