Abstract: Betula utilis and Picea purpurea seeds were collected from different a ltitudes on the eastern Qinghai-Tibet plateau;and their germination behavior u nder an alternative temperature regime (20 ℃/5 ℃; light/dark;12/12 h) foll owing cold storage (3 ℃〖KG-*2〗-〖KG-*7〗4 ℃; 0;40;80 and 160 days) was s tudied. The results showed that the germination rate of B. utilis and P. p urpurea seeds increased with increasing altitude of their mother plants;and t he seeds from different altitudinal populations tended to increase their germina tion rate with increasing duration of cold storage. In particular;the seeds of B. utilis from high altitude (3000 m) had a maximum germination percentage ( 94% and 90%;respectively) after cold storage for 80 and 160 days. The findings indicated that both the altitude of mother plants and the duration of cold and d ry storage had significant effects on the seed germination behavior of the two s pecies. The adaptive germination strategy;i.e.;regulating the timing of se ed germination;of the population individuals at different altitudes could maxim ize the probability of their seedling survival;and ensure their race proliferat ion.

Key words: Phragmites communis, Rhizome, Age class, Bud bank, Bud flow model, Dry land habitat, Alkalinized meadow