Abstract Construction of the Three Gorges Reservoir converted areas of the original terrestrial ecosystem along the shores into a draw-down zone with a fluctuating water-level at an elevation ranging between 145 and 175 m. The water-level fluctuation is regulated against the normal seasonal flooding with summer emergence and winter submergence. We investigated the seed rain and soil seed banks along elevational gradients of the Xiangxi zone in the reservoir to explore the characteristics of species composition and spatial distribution of seed rain and soil seed bank, and their similarities with standing vegetation under the regulated water-level fluctuation. The results showed that the seed rain and soil seed bank comprised 36 and 50 species of plants, respectively. These were predominantly annual herbaceous plants, which accounted for 54.02 and 66.0% of the seed rain and soil seed bank, respectively, with an average density of 445.16 ± 49.97 and 7322.18 ± 678.44 seeds/m2, respectively. The regulated water-level fluctuation resulted in greater species diversity and seed density of seed rain and soil seed bank in the middle and upper elevations of the zone than that of the lower elevations. The similarity coefficient between seed rain and seed bank, seed bank and extant vegetation, seed rain and extant vegetation was 0.488, 0.373 and 0.466, respectively. Effects of the regulated water-level fluctuation on the species compositions and spatial distribution of the seed rain and seed bank, and their similarities with existing vegetation were further discussed by contrast with the current research in the same field.

中文翻译：

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湘西河水位调控下水位下降带的种子雨和种子库及其与植被的相似性

摘要 三峡水库的建设，将原有陆地生态系统沿岸区域转变为海拔145～175 m、水位波动的下降带。水位波动受正常季节性洪水的调节，夏季出现，冬季淹没。沿水库湘西带海拔梯度调查了种子雨和土壤种子库，探索了种子雨和土壤种子库的物种组成和空间分布特征，以及它们在调节水位波动下与立地植被的相似性。 . 结果表明，种子雨和土壤种子库分别包含 36 和 50 种植物。这些主要是一年生草本植物，占 54 种。02 和 66.0% 的种子雨和土壤种子库，平均密度分别为 445.16±49.97 和 7322.18±678.44 粒/m2。受调节的水位波动导致中高海拔地区种子雨和土壤种子库的物种多样性和种子密度高于低海拔地区。种子雨与种子库、种子库与现存植被、种子雨与现存植被的相似系数分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。平均密度分别为 445.16±49.97 和 7322.18±678.44 粒种子/m2。受调节的水位波动导致中高海拔地区种子雨和土壤种子库的物种多样性和种子密度高于低海拔地区。种子雨与种子库、种子库与现存植被、种子雨与现存植被的相似系数分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。平均密度分别为 445.16±49.97 和 7322.18±678.44 粒种子/m2。受调节的水位波动导致中高海拔地区种子雨和土壤种子库的物种多样性和种子密度高于低海拔地区。种子雨与种子库、种子库与现存植被、种子雨与现存植被的相似系数分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。受调节的水位波动导致中高海拔地区种子雨和土壤种子库的物种多样性和种子密度高于低海拔地区。种子雨与种子库、种子库与现存植被、种子雨与现存植被的相似系数分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。受调节的水位波动导致中高海拔地区种子雨和土壤种子库的物种多样性和种子密度高于低海拔地区。种子雨与种子库、种子库与现存植被、种子雨与现存植被的相似系数分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。种子库和现存植被、种子雨和现存植被分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。种子库和现存植被、种子雨和现存植被分别为0.488、0.373和0.466。通过与同领域现有研究的对比，进一步讨论了调节水位波动对种子雨和种子库的物种组成和空间分布的影响，以及它们与现有植被的相似性。