PREMISE The ecological implications of hyperaccumulation have been investigated at the organismal level, but are poorly understood at the plant community level. Questions addressed here were: Does the presence of selenium (Se) hyperaccumulators affect Se distribution and concentration in their native soil, and do hyperaccumulators affect overall vegetation properties and species composition? METHODS Plant survey and soil Se mapping were performed at three seleniferous sites in Colorado. In season one, plots with and without hyperaccumulators were compared for (1) bare ground, canopy cover, and species richness; (2) relative species abundance; (3) soil Se distribution and concentration. In season two, a smaller-scale design was implemented, focusing on areas 3 m in diameter around hyperaccumulators versus nonhyperaccumulators in 44 paired plots on one site. RESULTS Plots with hyperaccumulators generally showed more bare ground, less canopy cover, higher species richness, and 2-3-fold higher soil Se levels. These patterns were not consistently significant across all sites; the effects of hyperaccumulators may have been diluted by their low abundance and the relatively large area of survey. In the smaller-scale study, highly significant results were obtained, showing more bare ground, less canopy cover, and higher species richness in plots with hyperaccumulators; soil Se concentration was also higher in plots with hyperaccumulators. CONCLUSIONS Hyperaccumulators may significantly affect local soil Se concentration and vegetation over at least a 3 m diameter area, or 4× their canopy. These differences may result from the combined positive and negative allelopathic effects observed earlier at the organismal level.

中文翻译：

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硒超富集剂对土壤硒分布和植被特性的影响

前提 已经在生物体水平上研究了超积累的生态影响，但在植物群落水平上却知之甚少。这里讨论的问题是：硒 (Se) 超富集植物的存在是否会影响其原生土壤中硒的分布和浓度，超富集植物是否会影响整体植被特性和物种组成？方法 在科罗拉多州的三个含硒地点进行了植物调查和土壤硒测绘。在第一季，比较了有和没有超积累植物的地块的 (1) 裸地、树冠覆盖和物种丰富度；(2) 相对物种丰度；(3)土壤Se的分布和浓度。在第二季中，实施了较小规模的设计，在一个地点的 44 个配对地块中，重点关注超累加器与非超累加器周围直径 3 m 的区域。结果 具有超富集植物的地块通常表现出更多的裸露地面、更少的冠层覆盖、更高的物种丰富度和 2-3 倍的土壤硒水平。这些模式在所有站点中并非始终显着；超积累植物的影响可能因它们的低丰度和相对较大的调查面积而被稀释。在较小规模的研究中，获得了非常显着的结果，显示出更多的裸地，更少的冠层覆盖，并且在超富集地块中物种丰富度更高；有超富集植物的地块的土壤硒浓度也较高。结论 超富集植物可能会显着影响至少 3 m 直径区域或 4 倍其冠层的当地土壤硒浓度和植被。