Characters And Trend Of Seeds Germinate In Autumn In Grurbantonggut Desert, China

The germination time of seeds scatters in different seasons, which contributes to the utilization of resources as well as the continuation and growth of their population. The common characteristics of autumn-germinated seeds and their environmental dependence of germination were studied via the investigation of the species of the autumn-germinated plants, their distribution characteristics in Grurbantonggut desert, the biological characteristics of the seeds and their germination response to temperature and moisture. we get conclusions:(1) Autumn-germinated species distribute in 33 sites among 67 sites and most species is ephemeral plants, accounting 25 species for 50% or more of the total number of ephemeral plants. Autumn-germination is widespread in Grurbantonggut Desert.(2) Seed germinates in different time can avoid possible risks. Seedling stage, roots and biomass of autumn-germinated are significantly greater than that of spring-germinated. With limited resources, autumn-germinated seedlings take a competitive advantage; Reproductive stage, a large number of seed yield of autumn-germinated contribute to population' continuity and expansion.(3) The high temperature range of seeds germination is broad and the germination type is not a low-temperature type of early spring and this is in correspondence to the temperature in the natural environment from September to November. Germination is sensitive to soil moisture and the RDA further reveals that moisture is a restricted factor to the germination time of seeds.(4) The fruits of autumn-germinated plants are easy to dehiscence; their seeds have a short life span; and they do not have dormancy.(5) With temperature increasing in winter and freeze time being shorten, it infers that climate change in autumn provides favorable conditions for seed germination, the proportion of seed germination prones to decrease when autumn-germination gets more advantage by model simulating. in another word, autumn-germination will sustain a stable degree under climate change if it's advantage is presented. Consequently, seed germination in Grurbantonggut Desert is determined both by seed itself and environment. In early time, propagule exists in soil as the form of seeds without the protection of parent plant. Those propagule must grow in a proper period during their limited life. In each autumn of a year, proper water temperature environment can provide an opportunity to make those seeds ripen.