Large dam removals effectively restore geomorphic and hydrologic processes, but little is known about subsequent vegetation recovery and the role of active restoration. We studied whether planting and seeding affected vegetation recovery in a dewatered reservoir, and whether effects differed on landforms composed of fine or coarse-textured sediments. The dewatered reservoir is behind the former Glines Canyon Dam, which was removed from the Elwha River in Washington State (U.S.A.) in 2011–2014. We measured bare ground in 2013–2017, and species richness, relative frequency of non-native species, woody stem density, and species composition in 2016. Sediment texture affected all response variables. Several years after seeding, bare ground was reduced on coarse sediments and non-native species frequency was reduced on both textures. Planting increased species richness. Seeding and planting altered species composition on both textures, with stronger effects on coarse sediments. High densities of riparian woody plants naturally established on fine sediments, reaching a mean of 34,000 stems/ha 5 years after dam removal began; density was only a fraction of this (5,000 stems/ha) on coarse sediments. Future dam removals should incorporate sediment texture into their revegetation plans. Seeding and planting can be valuable strategies for minimizing non-native species frequency, increasing species richness, and establishing desirable target species after dam removal, particularly on landforms composed of coarse sediments.

中文翻译：

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大坝拆除后的种植、播种和沉积物影响恢复成功

大坝拆除有效地恢复了地貌和水文过程，但对随后的植被恢复和主动恢复的作用知之甚少。我们研究了种植和播种是否影响脱水水库中的植被恢复，以及对由细或粗纹理沉积物组成的地貌的影响是否不同。脱水水库位于前 Glines Canyon 大坝后面，该大坝于 2011-2014 年从华盛顿州（美国）的 Elwha 河中拆除。我们测量了 2013-2017 年的裸地，以及 2016 年的物种丰富度、非本地物种的相对频率、木本茎密度和物种组成。沉积物质地影响所有响应变量。播种几年后，粗糙的沉积物减少了裸地，两种质地的非本地物种频率都减少了。种植增加了物种丰富度。播种和种植改变了两种质地的物种组成，对粗沉积物的影响更大。高密度的河岸木本植物自然生长在细小的沉积物中，在大坝拆除开始 5 年后平均达到 34,000 株/公顷；在粗糙的沉积物中，密度只是其中的一小部分（5,000 茎/公顷）。未来的大坝拆除应将沉积物质地纳入其重新植被计划。播种和种植可能是减少非本地物种频率、增加物种丰富度和在大坝拆除后建立理想目标物种的有价值的策略，特别是在由粗沉积物组成的地形上。高密度的河岸木本植物自然生长在细小的沉积物中，在大坝拆除开始 5 年后平均达到 34,000 株/公顷；在粗糙的沉积物中，密度只是其中的一小部分（5,000 茎/公顷）。未来的大坝拆除应将沉积物质地纳入其重新植被计划。播种和种植可能是减少非本地物种频率、增加物种丰富度和在大坝拆除后建立理想目标物种的有价值的策略，特别是在由粗沉积物组成的地形上。高密度的河岸木本植物自然生长在细小的沉积物中，在大坝拆除开始 5 年后平均达到 34,000 株/公顷；在粗糙的沉积物中，密度只是其中的一小部分（5,000 茎/公顷）。未来的大坝拆除应将沉积物质地纳入其重新植被计划。播种和种植可能是减少非本地物种频率、增加物种丰富度和在大坝拆除后建立理想目标物种的有价值的策略，特别是在由粗沉积物组成的地形上。