Riparian buffers implemented to minimize sediment, nutrients, and disturbance impacts on streams during forest operations vary greatly in the degree to which ecological criteria are used in their design. Because most forest operations are concentrated around headwater streams, our primary research objective was to identify a floristically based riparian boundary for headwater streams using plant species composition and indicator species to classify riparian environments distinct from the surrounding upland forest. Within three forested regions of the Northeast US, understory vegetation plots were sampled along perpendicular transects extending from the stream bank into the upland forest. At all sites, species richness was highest adjacent to the stream, decreasing exponentially within 6–12 m from the channel. Species composition closest to the stream was significantly different from all other lateral distances, but identified riparian indicator species were of limited practical use across all sites. However, changes in species richness can serve to identify a riparian area extent up to 6–12 m from headwater streams.

中文翻译：

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林下植物组成和丰富度能否帮助指定美国东北部梅西克源头森林的河岸管理区？

在森林经营过程中，为最大限度地减少沉积物、养分和干扰对河流的影响而实施的河岸缓冲区在其设计中使用生态标准的程度方面存在很大差异。由于大多数森林作业都集中在源头溪流周围，我们的主要研究目标是使用植物物种组成和指示物种来确定与周围高地森林不同的河岸环境，以确定源头溪流的基于植物学的河岸边界。在美国东北部的三个森林区域内，沿从河岸延伸到高地森林的垂直样带对林下植被地块进行采样。在所有地点，靠近河流的物种丰富度最高，在距离河道 6-12 m 范围内呈指数下降。最接近河流的物种组成与所有其他横向距离显着不同，但确定的河岸指示物种在所有地点的实际用途有限。然而，物种丰富度的变化可用于确定距源头河流达 6-12 m 的河岸区域范围。