中文摘要：

种子雨在一定程度上决定了植物群落的更新潜能和演变趋势.采用种子雨萌发实验,研究香溪河消落带人工和自然恢复模式下消落带种子雨物种组成、多样性和密度特征及其动态变化.结果表明,不同植被恢复模式下消落带种子雨的物种组成和物种多样性及其时空动态有较大差异.其中人工恢复地种子雨包含29种植物,而自然恢复地有36种,组成均以一年生和多年生草本为主.人工恢复地的物种多样性指数低于、但优势度指数高于自然恢复地.种子雨的多样性以消落带出露初期和后期为高,中期较低;消落带中上部高于中下部.人工恢复地种子雨月平均密度为150.09（±34.118）粒/m2,以7月份为最高;而自然恢复地为138.72（±51.298）粒/m2,以4月份为最高.人工恢复地各水位高度种子雨平均密度为489.60（±31.195）粒/m2,自然恢复地为445.16（±49.974）粒/m2,空间分布均以165 m处的种子雨平均密度最高.两种恢复地的地表植物群落和种子雨的相似性较高,其中人工恢复地相似系数略高于自然恢复地.综上所述,人工恢复有效增加了消落带植物群落种子雨的密度,并对种子雨的组成和时空分布产生影响,促进了消落带,特别是消落带下部等难以恢复地段植物群落的生态恢复.

英文摘要：

Seed rain determines the regeneration potential and evolution of plant community to a certain extent. This research aimed to explore the characteristics and dynamics of composition, biodiversity and density of seed rain through germination experiments of samples collected from the artificial and natural restoration sites in the drawdown zone of the Xiangxi River. The results showed that restoration method had significant effects on the composition, biodiversity and temporal and spatial dynamics of seed rain. There were 29 species in seed rain on the artificial restoration sites and 36 species on the natural restoration sites. The seed rain was mainly composed of annual and perennial herbaceous species in both of the restoration sites. The species biodiversity index of the artificial restoration sites was lower than that of the natural restoration site, but its dominance index was higher than that of the natural restoration site. The biodiversity of seed rain was relatively higher during the early and late exposing periods of the drawdown zone, but lower during the medium exposing period. The biodiversity of seed rain on the middle and upper part of the drawdown zone was higher than that on the middle and lower part. The monthly average density of seed rain on the artificial restoration site was about 150.09 （± 34.118）/m2. peaking in July, but was about 138.72 （± 51.298）/m2 on the natural restoration site peaking in April. The average density of seed rain in all water levels was about 489.60 （± 31.195）/m2 in the artificial restoration site and 445.16 （± 49.974）/m2 in the natural restoration site, with the highest density at 165 m in both restoration sites. The two restoration sites had a high similarity index of species composition between plant community and seed rain, though that of the artificial restoration site was relatively higher than the natural restoration site. It is concluded that artificial restoration effectively increases the seed rain density of riparian plant community in the d