Effects of riparian vegetation on fluvial sediment dynamics depend on morphological traits of the constituent species. Determining the effects of different morphological guilds on sedimentation rates, as influenced by multiple aspects of dam operations, can help identify viable strategies for streamflow and vegetation management to achieve riparian resource goals. Plants of increasing size and branching density or complexity have been found to have greater effects on sedimentation in free‐flowing systems; however, this relationship could differ in regulated rivers. We tested the hypothesis that plant guilds of increasing height and branching complexity would be positively associated with sedimentation rates on 23 sandbars deposited in zones of recirculating flow (eddies) along the Colorado River in Grand Canyon. We used an image‐based vegetation classification and digital elevation models from annual topographic surveys to track associations between six plant morphological guilds and topographic change over 5 years. Vegetation had significant associations with deposition after accounting for geomorphic setting, but the ordinal guild scale was not positively correlated with deposition magnitude. Instead, low‐statured rhizomatous and herbaceous guilds were particularly effective at capturing sediment in the separation zone of sandbars, whereas tall herbs and large shrubs were most effective at capturing sediment in reattachment zones. These nuanced interactions between geomorphic position and morphological guild may be a direct consequence of flow regulation through modifications to physical deposition and erosion processes. Flow regulation may also select for a narrow subset of morphological guilds, reducing the diversity of vegetation feedbacks on sedimentation and emphasizing geomorphic drivers.

中文翻译：

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大峡谷受管制的科罗拉多河沿岸植物形态学群与河流沉积物动力学之间的关联

河岸植被对河流沉积物动力学的影响取决于组成物种的形态特征。确定受大坝运营多方面影响的不同形态学对沉积速率的影响，可以帮助确定可行的水流和植被管理策略，以实现河岸资源目标。已经发现越来越大的植物和分枝密度或复杂性对自由流动系统中的沉积有更大的影响；然而，这种关系在受管制的河流中可能有所不同。我们检验了这样一种假设，即高度增加和分枝复杂性增加的植物行会与大峡谷沿科罗拉多河再循环流（涡流）区域中沉积的 23 个沙洲的沉积速率呈正相关。我们使用来自年度地形调查的基于图像的植被分类和数字高程模型来跟踪 5 年内六个植物形态学协会与地形变化之间的关联。考虑到地貌背景，植被与沉积有显着关联，但序数行会规模与沉积量级不呈正相关。相反，矮小的根状茎和草本植物群在捕获沙洲分离区的沉积物方面特别有效，而高大的草本植物和大灌木在捕获重附着区的沉积物方面最有效。地貌位置和形态行会之间的这些细微相互作用可能是通过修改物理沉积和侵蚀过程进行流量调节的直接结果。