Data from: The hydrochorous dispersal of plant propagules in a giant river reservoir: implications for restoration of riparian vegetation

The riparian vegetation of many rivers around the world is impacted by flow regulation for hydropower. Water levels behind dams are being raised to generate electric energy, forming river reservoirs. River regulation has a large impact on the riparian vegetation which influences both the adjacent aquatic and terrestrial ecosystems. Therefore, restoration of degraded riparian vegetation in river reservoirs has been of increasing research interest. Propagules dispersed from connected tributaries via water (hydrochory) are considered a vital source for the recovery of riparian vegetation in regulated rivers. However, the hydrochorous dispersal of plant propagules in river reservoirs is unclear. We explored the dispersal distance and deposition patterns of hydrochorous propagule mimics in three tributaries that are regulated by the Three Gorges Reservoir (TGR) in China. In eight out of nine release experiments, 95% of propagule mimics were found within 3 km downstream from the release points. Cumulative wind speed was the most important factor affecting the dispersal distance of propagule mimics in the TGR. However, the dispersal distance of propagule mimics was not significantly affected by water-level variation and channel sinuosity. Variations in water level strongly affected the deposition pattern of propagule mimics, with only 6.6% of the propagule mimics stranding on the riparian zones under raised water level and 83.8% stranding under declined water levels. The majority of stranded propagule mimics were deposited at gentle slopes (0‒20°). Synthesis and applications. Our results suggest that the majority of propagules that enter river reservoirs via water would be retained within the first few kilometers. Wind and water level variation are the main factors determining the dispersal distance and deposition pattern of propagules. Our findings have applications for riparian vegetation restoration in river reservoirs. The vegetation in steep riparian zones distant from free-flowing tributaries should be the priority for restoration actions because these areas receive limited hydrochorous propagules. The plant biodiversity and hydrological connectivity of connected tributaries, which is an important propagule sources for riparian vegetation along river reservoirs, should be protected. The seasonal dominant wind pattern should be considered when evaluating the importance of tributaries as the source of hydrochorous propagules for river reservoirs.全球诸多河流的河岸植被（riparian vegetation）均受到水力发电水流调控（flow regulation）的影响。大坝库区水位被抬高以生产电能，进而形成人工水库（river reservoirs）。河流径流调控对河岸植被影响显著，而河岸植被同时会对相邻的水生（aquatic）与陆生（terrestrial）生态系统产生双向作用。因此，河流水库中退化河岸植被的修复已逐渐成为国际研究热点。通过水体从连通支流扩散而来的植物繁殖体（propagules），其传播方式为水媒传播（hydrochory），被认为是受调控河流中河岸植被恢复的关键种源。然而，目前针对河流水库内植物繁殖体水媒传播过程的认知仍较为匮乏。本研究以中国三峡水库（Three Gorges Reservoir, TGR）调控范围内的三条支流为研究对象，探究了水媒传播繁殖体模拟物的传播距离与沉积模式。在9组释放实验（release experiments）中的8组里，95%的繁殖体模拟物均在释放点下游3公里范围内被回收。累积风速（cumulative wind speed）是影响三峡水库内繁殖体模拟物传播距离的最关键驱动因子，而水位变化（water-level variation）与河道弯曲度（channel sinuosity）并未对其传播距离产生显著影响。水位变化则会显著调控繁殖体模拟物的沉积模式：当库区水位抬升时，仅6.6%的繁殖体模拟物会附着沉积于河岸带；而当水位下降时，该沉积占比可达83.8%。绝大多数附着沉积的繁殖体模拟物均分布在缓坡（0°~20°）区域。总结与应用。本研究结果表明，通过水体进入河流水库的绝大多数植物繁殖体都会被截留于下游数公里范围内。风速与水位变化是决定繁殖体传播距离与沉积模式的核心因素。本研究发现可为河流水库的河岸植被修复提供实践指导：距离自由流动支流较远的陡峭河岸带植被应作为修复优先目标，因为此类区域获取的水媒繁殖体十分有限。作为水库沿岸河岸植被的重要繁殖体来源，连通支流的植物生物多样性（plant biodiversity）与水文连通性（hydrological connectivity）应当得到严格保护。在评估支流作为水库水媒繁殖体来源的重要性时，应当充分考虑区域季节性主导风向模式。