Quantifying flooding regime in floodplain forests to guide river restoration

Determining the flooding regime needed to support distinctive floodplain forests is essential for effective river conservation under the ubiquitous human alteration of river flows characteristic of the Anthropocene Era. At over 100 sites throughout the Connecticut River basin, the largest river system in New England, we characterized species composition, valley and channel morphology, and hydrologic regime to define conditions promoting distinct floodplain forest assemblages. Species assemblages were dominated by floodplain-associated trees on surfaces experiencing flood durations between 4.5 and 91 days/year, which were generally well below the stage of the two-year recurrence interval flood, a widely-used benchmark for floodplain restoration. These tree species rarely occurred on surfaces that flooded less than 1 day/year. By contrast abundance of most woody invasive species decreased with flooding. Such flood-prone surfaces were jointly determined by characteristics of the hydrograph...

在人类世（Anthropocene Era），河流流量普遍受到人类活动改变，在此背景下确定维持独特洪泛平原森林所需的水文节律，对于开展有效的河流保护工作至关重要。我们在新英格兰最大水系——康涅狄格河流域（Connecticut River basin）的100余个监测站点中，对物种组成、河谷与河道形态以及水文节律进行了表征分析，以明确促进独特洪泛平原森林群落形成的环境条件。在每年洪水淹没时长介于4.5至91天的区域，森林群落以与洪泛平原相关的乔木为优势种；该淹没时长通常远低于两年一遇洪水的水位，而两年一遇洪水是洪泛平原修复领域广泛使用的基准指标。这些乔木物种极少出现在每年洪水淹没时长不足1天的区域。与之相反，多数木本入侵物种的多度随洪水淹没时长的增加而降低。这类易受洪水淹没的区域的特征由水文过程线（hydrograph）的各项特征共同决定……