Dams fragment the longitudinal flux of sediment and obstruct fish passage. To help remediate these impacts, dam removal has become an important tool in the river restoration toolkit. Scientifically, these removals also provide an important experimental design, fixed in time and space, to quantify geomorphic and ecological responses to removal of a disturbance. Using the removal of a 6 m high dam in Massachusetts (USA), we quantify the immediate and subsequent channel and ecological recovery to test whether the immediate ecological/geomorphic responses were sustained or transient. Initial geomorphic adjustments have been generally sustained since removal, especially for bed sediment size, where initial fining and reduction in bed caliber size has been maintained over the course of the study. Sampling of transported passive integrated transponder (PIT) tagged clasts indicates that the median of bedload grain sizes now corresponds to surface median grain sizes below the former dam. Channel cross-sectional area varied irregularly downstream initially but is now spatially uniform. Pool filling, however, has been a transient response as initial aggradation shifted to sediment evacuation. Ecologically, upstream establishment of resident fish species previously restricted to below-dam locations occurred in the first year after removal. Upstream expansion increased upstream species richness and has been maintained throughout the study period, in spite of the variability in presence and abundance of rare and migratory species such as the anadromous Sea lamprey (Petromyzon marinus). In contrast, a reduction in abundance of resident species in dam proximal sites in 2012 appears to be a transient response to abrupt and intense bed movement associated with removal of the dam, as numbers recovered and, in some cases, exceeded pre-dam removal levels. Overall, we found that immediate (within the first 1–2 yr), sustained effects on geomorphology and ecology dominated the response to dam removal in this system, a finding that may be generally applicable to small dam removals in upland catchments.

大坝会破坏沉积物的纵向通量并阻碍鱼类通过。为了帮助补救这些影响，大坝拆除已成为河流恢复工具包中的一个重要工具。从科学上讲，这些移除还提供了一个重要的实验设计，在时间和空间上是固定的，以量化对干扰移除的地貌和生态响应。通过拆除马萨诸塞州（美国）一座 6 m 高的大坝，我们量化了直接和随后的渠道和生态恢复，以测试直接的生态/地貌响应是持续的还是短暂的。最初的地貌调整自移除以来一直持续，特别是床沉积物尺寸，在研究过程中保持初始细化和床口径尺寸的减小。运输的被动集成转发器 (PIT) 标记碎屑的采样表明，床载粒度的中值现在对应于前大坝下方的表面中值粒度。河道横截面积最初在下游不规则地变化，但现在在空间上是一致的。然而，随着初始聚集转变为沉积物排出，水池填充一直是一种瞬态反应。在生态上，以前仅限于坝下位置的常驻鱼类在上游建立后的第一年发生。上游扩张增加了上游物种的丰富度，并在整个研究期间一直保持，尽管稀有和迁徙物种（如溯河海七鳃鳗）的存在和丰度存在差异。河道横截面积最初在下游不规则地变化，但现在在空间上是一致的。然而，随着初始聚集转变为沉积物排出，水池填充一直是一种瞬态反应。在生态上，以前仅限于坝下位置的常驻鱼类在上游建立后的第一年发生。上游扩张增加了上游物种的丰富度，并在整个研究期间一直保持，尽管稀有和迁徙物种（如溯河海七鳃鳗）的存在和丰度存在差异。河道横截面积最初在下游不规则地变化，但现在在空间上是一致的。然而，随着初始聚集转变为沉积物排出，水池填充一直是一种瞬态反应。在生态上，以前仅限于坝下位置的常驻鱼类在上游建立后的第一年发生。上游扩张增加了上游物种的丰富度，并在整个研究期间一直保持，尽管稀有和迁徙物种（如溯河海七鳃鳗）的存在和丰度存在差异。原先仅限于大坝以下位置的常驻鱼类在上游建立，发生在移除后的第一年。上游扩张增加了上游物种的丰富度，并在整个研究期间一直保持，尽管稀有和迁徙物种（如溯河海七鳃鳗）的存在和丰度存在差异。原先仅限于大坝以下位置的常驻鱼类在上游建立，发生在移除后的第一年。上游扩张增加了上游物种的丰富度，并在整个研究期间一直保持下去，尽管稀有和迁徙物种（如溯河海七鳃鳗）的存在和丰度存在差异。Petromyzon marinus）。相比之下，2012 年大坝附近地区常驻物种丰度的减少似乎是对与大坝拆除相关的突然和强烈河床移动的短暂反应，因为数量恢复，并且在某些情况下超过大坝拆除前的水平. 总体而言，我们发现对地貌和生态的直接影响（在前 1-2 年内）主导了该系统对大坝拆除的响应，这一发现可能普遍适用于高地集水区的小坝拆除。