Abstract: Cleistogenes songorica and Plantago lessingii are the important native plant species in desert grasslands of northwest China,and play a significant role in pasture production and vegetation restoration.The study on the seed germination characteristics of C.songorica and P.lessingii under different light,salinity and sowing depth showed that C.songorica and P.lessingii seeds had a higher germination rate when fostered in light than in dark.The germination rate declined linearly with increasing NaCl concentration ranged from 0 to 0.3 mol·L^-1,and decreased faster for C.songorica than P.lessingii.The seeds of these two species could not germinate when the NaCl concentration reached 0.4 mol·L^-1.A low NaCl concentration could promote radicle growth,while excessive NaCl would lead to inhibition.Salinity always prohibited the germination of test seeds.Seed germination rate decreased with increasing sowing depth,and no germination was found when the sowing depth was > 2 cm.

Key words: Jujube orchard, Arthopod, Community structure, Temporal dynamic, Fuzzy clustering