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Leymus chinensis is a dominant and most promising grass species in the Songnen Grassland of Northern China. Experiments were conducted to determine the effect of temperature, salinity, alkalinity and their interactions on seed germination. Seeds were germinated at four alternating temperatures (10-20, 15-25, 20-30 and 25-35°C), with saline stress (9:1 molar ratio of NaCl:Na 2-SO 4 ) and alkaline stress (9:1 molar ratio of Na 2 CO 3 :NaHCO 3 ). Germination percentage and rate were inhibited by either an increase or decrease in temperature from the optimal temperature range of 20-30°C, and were also inhibited by an increase in salinity and alkalinity at all temperatures. The inhibitory effects of high salinity on germination were greater at 25-35°C, but seeds were subjected to more stress even though the alkalinity was low under this temperature. Recovery percentage was highest at 400 mM M salinity at 20-30°C, but only at 100 mM M alkalinity, and 25-35°C also resulted in lower recovery percentage under both stresses. Results suggest that saline stress and alkaline stress have different impacts on seed germination and that saline-alkaline tolerance of L. chinensis seeds is affected by the interactions of temperature and salinityalkalinity. Early July sowing in the field is recommended when temperature is optimal and salinity-alkalinity concentrations are reduced by the high rainfall.

To understand how shrub cover affects the spatiotemporal patterns of the soil seed bank and to assess the role of vegetation in the restoration of desertified land in a semi‐arid region of China, we investigated the species composition and seed density of the soil seed bank under and outside the canopies over two seasons for an age sequence of Caragana microphylla shrubs in the Horqin Sandy Land region, Inner Mongolia. The results showed that a total of 24 plant species seeds were present in the soil seed bank, of which 20 were annuals or biennials. The seed densities in the soil seed bank were in the range of 830 – 13882·5 seeds m−2 at 10 cm depth. Species richness in the soil seed bank did not increase as the shrubs aged, whereas the seed densities increased significantly. Five annual species: Setaria viridis, Eragrostis pilosa, Chenopodium acuminatum, Chenopodium glaucum and Corispermum acuminatum, contributed above 90 per cent of the seeds to the soil seed bank. On the basis of seed characteristics and seed reduction amount during the growing season, we concluded that it represents a mixture of persistent and transient seeds in different proportions. More seeds accumulated under the canopies than outside the mature shrub cover, but no significant difference was found the younger cover. These results suggest that shrub size and age had an important role in augmenting seed abundance of the soil seed bank but not the species richness. We confirmed the important effects of shrub cover on seed accumulation and vegetation recovery, especially the value of more mature age vegetation for countering land degradation. Copyright © 2012 John Wiley & Sons, Ltd.