中文摘要：

对新疆干旱区分布的濒危物种大赖草的种子雨及土壤种子库动态进行了研究。结果表明，大赖草的种子8月上旬成熟，散落从8月中旬一直持续到10月初，散落的高峰期集中在9月上旬。种子成熟后因自身重力多集中于母株附近，同时还受风向、地形和天气等因素的影响；种子雨共采集到种子457粒，仅有18．6％为成熟饱满种子。土壤种子库中秋、春两季在O～2cm层中分布的种子数量分别占总种子数的80．5％和58．0％，其余种子分布在2～6cm层。土壤种子库中的种子数量受大赖草的个体分布、周围植被的密度、地形等诸多因素的影响；秋、春两季共得到种子分别为108粒、62粒，其中成熟饱满种子仅为24粒、4粒，各占总种子数的22．22％和6．45％。大赖草生长环境恶劣、种子雨及土壤种子库中种子从数量到质量均较差，严重影响了大赖草种群的自然更新。

英文摘要：

Leymus racernosus （Lain.） Tzvel is an endangered species in arid areas of Xinjiang,China.The dynamic characteristics of seed rain and soil seed bank of L. racemosus were studied in this paper. Results showed that the seed of L. racemosus began to mature in the first ten-day period of August; the seed rain occurred from in the middle ten-day of August to early October and the peak of scattered seed rain concen- trated in the first ten-day of September. The seeds mainly scattered around mother plants; besides, the wind direction, topography and weather also influenced the seed dispersal. A total of 452 seeds were col-lected during the period of seed rain,but the matured seeds only accounted for 18.6%.The numbers of soil seed bank at 0-2 cm soil layer occupied by 80.5% and 58.0% of total amount of soil seed bank in autumn and spring,respectively;the rest of soil seed bank distributed at 2-6 cm layer.The soil seed bank of L. racemosus was influenced by the distribution of mother plant, individual plant density of the surrounding vegetationand topography, etc. 1 0 8 and 6 9 seeds were obtained in autumn and spring respectively, but with the matured seeds of 24 and 4 only,accounting for 22.22% and 6.45% of the total seeds, respectively. In conclusion,the habitat where L. racemosus grew population was worse, the quantity and quality of seed rain and soil seed bank were low; these were unfavorable for the natural reproduction of L. racemosus pop-ulation.