Stream drying is increasing globally, with widespread impacts on stream ecosystems. Here, we investigated how the impacts of drying on stream ecosystem connectivity might depend on stream network size and the location of drying within the stream network. Using 11 stream networks from across the United States, we simulated drying scenarios in which we varied the location and spatial extent of drying. We found that the rate of connectivity loss varied with stream network size, such that larger stream networks lost connectivity more rapidly than smaller stream networks. We also found that the rate of connectivity loss varied with the location of drying. When drying occurred in the mainstem, even small amounts of drying resulted in rapid losses in ecosystem connectivity. When drying occurred in headwater reaches, small amounts of drying had little impact on connectivity. Beyond a certain threshold, however, connectivity declined rapidly with further increases in drying. Given the increasing stream drying worldwide, our findings underscore the need for managers to be particularly vigilant about fragmentation when managing at large spatial scales and when stream drying occurs in mainstem reaches.

中文翻译：

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河流干燥的影响取决于河流网络的大小和干燥的位置


全球河流干涸现象日益严重，对河流生态系统产生了广泛影响。在这里，我们研究了干燥对河流生态系统连通性的影响如何取决于河流网络的大小和干燥在河流网络内的位置。我们使用来自美国各地的 11 个河流网络模拟了干燥场景，其中我们改变了干燥的位置和空间范围。我们发现连接丢失率随流网络大小而变化，因此较大的流网络比较小的流网络丢失连接的速度更快。我们还发现，连通性丢失的速度随干燥位置的不同而变化。当主干发生干燥时，即使是少量的干燥也会导致生态系统连通性迅速丧失。当源头发生干燥时，少量干燥对连通性影响不大。然而，超过一定阈值后，随着干燥程度的进一步增加，连通性迅速下降。鉴于全球河流干涸现象日益严重，我们的研究结果强调，管理者在进行大空间尺度管理以及干流干河段发生河流干涸时，需要特别警惕碎片化问题。