Conceptual models underpin river ecosystem research. However, current models focus on continuously flowing rivers and few explicitly address characteristics such as flow cessation and drying. The applicability of existing conceptual models to nonperennial rivers that cease to flow (intermittent rivers and ephemeral streams, IRES) has not been evaluated. We reviewed 18 models, finding that they collectively describe main drivers of biogeochemical and ecological patterns and processes longitudinally (upstream‐downstream), laterally (channel‐riparian‐floodplain), vertically (surface water‐groundwater), and temporally across local and landscape scales. However, perennial rivers are longitudinally continuous while IRES are longitudinally discontinuous. Whereas perennial rivers have bidirectional lateral connections between aquatic and terrestrial ecosystems, in IRES, this connection is unidirectional for much of the time, from terrestrial‐to‐aquatic only. Vertical connectivity between surface and subsurface water occurs bidirectionally and is temporally consistent in perennial rivers. However, in IRES, this exchange is temporally variable, and can become unidirectional during drying or rewetting phases. Finally, drying adds another dimension of flow variation to be considered across temporal and spatial scales in IRES, much as flooding is considered as a temporally and spatially dynamic process in perennial rivers. Here, we focus on ways in which existing models could be modified to accommodate drying as a fundamental process that can alter these patterns and processes across spatial and temporal dimensions in streams. This perspective is needed to support river science and management in our era of rapid global change, including increasing duration, frequency, and occurrence of drying.

中文翻译：

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河流生态系统概念模型和非多年生河流：严格审查

概念模型是河流生态系统研究的基础。但是，当前的模型集中在连续流动的河流上，很少明确涉及诸如断流和干燥等特征。尚未评估现有概念模型对停止流动的非多年生河流（间歇性河流和短暂河流，IRES）的适用性。我们审查了18个模型，发现它们共同描述了局部和景观尺度上纵向（上游-下游），横向（河道-河岸-洪泛区），纵向（地表水-地下水）和时间的生物地球化学和生态模式和过程的主要驱动力。但是，多年生河流在纵向上是连续的，而IRES在纵向上是不连续的。尽管多年生河流在水生生态系统和陆地生态系统之间具有双向横向联系，但在IRES中，这种联系在大部分时间都是单向的，仅从陆地到水生。在多年生河流中，地表水和地下水之间的垂直连接是双向发生的，并且在时间上是一致的。但是，在IRES中，这种交换在时间上是可变的，并且在干燥或重新润湿阶段可以变成单向的。最后，干旱增加了在IRES中跨时空尺度考虑的流量变化的另一个维度，就像洪水在多年生河流中被视为时空动态过程一样。这里，我们专注于修改现有模型以适应干燥的基本方法，该方法可以改变河流中时空维度上的这些模式和过程。在全球快速变化的时代，包括持续时间，频率和干旱的增加，需要这种观点来支持河流科学和管理。