Environment-dependence of seed germination in autumn in Grurbantonggut Desert

Seed germination time scatters in different seasons,being propitious to the resources utilization and the population continuation and growth.In this paper,a field survey was conducted on the autumn-germinating plant species and their distribution in Grurbantonggut Desert,and,based on the biological characteristics of their seeds and the responses of the seeds germination to air temperature and soil moisture,the common characteristics of the seeds and the environment-dependence of their germination were studied.Among the 67 sites surveyed,33 sites had autumn-germinating species,and most of them were ephemeral plants.The fruits of autumngerminating plants were easy to dehiscence,and the seeds had a shorter life span without dormancy.The seed germination had a broader high temperature threshold,and the germination type was not a low-temperature type of early spring but in correspondence to the temperature in autumn(September-November).The germination was sensitive to soil moisture.Redundancy analysis further revealed that soil moisture was a limiting factor to the germination time of the seeds,and affected the distribution of autumn-germinating plants.Because of the increasing precipitation in autumn and winter and the shortening frozen period in winter under the background of climate change,it was deduced that that the species and number of autumn-germinating plants in Gurbantunggut Desert would be increased.