Effects of rehabilitation of "black soil type" degraded grassland into sowing grasslands on soil seed bank and its relationship with vegetation in the source area of Yellow River

Soil seed bank and its relationship with aboveground vegetation of black soil type degraded grassland and two sowing grasslands,single seed and mixed seeds treatments were studied.The result showed that the soil seed bank is composed by 22 species in sowing grasslands and CK.Single seed grassland,mixed seeds grassland and black soil type degraded grassland are composed by 13,12 and 21 species respectively.Perennial weeds proportion of total number of species was 61.5%,50% and 61.9%.The size of soil seed bank of each experiment treatment is small.The seeds number of single seed grassland,mixed seeds grassland and black soil type degraded grassland is(4 142.8±1 547.6)、(5 057.8±943.3) and(1 591.5±876.9) seeds/m2 respectively.The similarity of species between soil seed bank and aboveground vegetation of black soil type degraded grassland is high.But it is low of each treatment.And the similarity is high between two treatments.