Riparian ecosystems are shaped by interactions among streamflow, plants, and physical processes. Sustaining functioning riparian ecosystems in the face of climate change, growing human demands for water, and increasing water scarcity requires improved understanding of the sensitivity of riparian ecosystems to shifts in flow regimes and associated adaptive management strategies. We applied projected future flow regimes to an ecogeomorphic model of riparian and channel response to evaluate these interactions. We tested the hypothesis that components of the riparian ecosystem vary in their vulnerabilities to shifts in flow attributes and that changes in the representation of functional groups of plants result from interactions between ecological and physical drivers. Using the Yampa and Green Rivers in northwestern Colorado as our test system, we investigated ecogeomorphic response to (1) synthetic flow regimes representing continuous changes from baseline flows; and (2) future flow scenarios that incorporate changing climate, demand, and water-resource projects. For this region, we showed that riparian plant presence, composition, and cover are highly sensitive to the high flows that occur early in the growing season, but that shifts to low flows are also important, especially for determining the functional diversity of a riparian community. Future flow regimes are likely to induce vegetation encroachment on lower channel surfaces and to increase plant cover, which will be dominated by fewer functional groups. In particular, we predict a decrease in some mesic plants (shrubs and tall herbs) and an increase in presence and cover of late-seral, xeric shrubs, most of which are non-native species. Managing for high flows that occur early in the growing season must complement maintenance of adequate baseflows to maintain ecosystem functioning in the face of hydrologic alterations induced by climate change and human water demand.

河岸生态系统是由水流，植物和物理过程之间的相互作用所形成的。在气候变化，人类对水的需求不断增长以及水资源短缺的情况下，要维持河岸生态系统的正常运转，就需要更好地了解河岸生态系统对流量变化和相关适应性管理策略的敏感性。我们将预计的未来流态应用于河岸和通道响应的生态地貌模型，以评估这些相互作用。我们检验了以下假设：河岸生态系统的组成部分易受流量属性变化的影响而变化，并且植物功能组的表示形式的变化是由生态和物理驱动因素之间的相互作用导致的。以科罗拉多州西北部的Yampa和Green Rivers作为我们的测试系统，我们研究了对（1）代表从基线流量连续变化的合成流量模式的生态地貌响应；（2）结合不断变化的气候，需求和水资源项目的未来流量方案。对于该区域，我们表明，河岸植物的存在，组成和覆盖率对生长期初期发生的高流量高度敏感，但向低流量的转变也很重要，尤其是对于确定河岸社区的功能多样性而言。未来的水流态势可能会在较低的河道表面上引起植被侵蚀，并增加植物的覆盖率，而这将以较少的官能团为主导。特别是，我们预测某些杂种植物（灌木和高大的草药）的数量会减少，晚生，干燥的灌木的存在和覆盖率会增加，其中大多数是非本地物种。应对生长期初期出现的高流量进行管理，必须补充适当的基本流量，以应对气候变化和人类需水引起的水文变化而维持生态系统的功能。