Weighting effective number of species measures by abundance weakens detection of diversity responses

1. The effective number of species (ENS) has been proposed as a robust measure of species diversity that overcomes several shortcomings of both diversity indices and species richness measures. However, it is not yet clear if ENS improves interpretation and comparison of biodiversity monitoring data, and ultimately resource management decisions. 2. We used simulations of five stream macroinvertebrate assemblages and spatially extensive field data of stream fishes and mussels to show (1) how different ENS formulations respond to stress and (2) how diversity-environment relationships change with values of q, which weight ENS measures by species abundances. 3. Values of ENS derived from whole simulated assemblages with all species weighted equally (true species richness) steadily decreased as stress increased, and ENS-stress relationships became weaker and more different among assemblages with increased weighting. 4. The amount of variation in ENS across the fish and mussel assemblages t...1. 有效种数（effective number of species, ENS）是一种稳健的物种多样性测度指标，被提出以克服现有多样性指数与物种丰富度测度的多项固有缺陷。但目前仍不明确，ENS能否优化生物多样性监测数据的解读与对比，最终支撑资源管理决策。 2. 本研究通过对5类溪流大型无脊椎动物群落开展模拟实验，并结合大范围空间覆盖的溪流鱼类与蚌类野外实测数据，开展了两项探究：其一，不同ENS计算形式如何响应环境胁迫；其二，多样性-环境关系如何随权重参数q的取值发生变化——该参数通过物种丰度对ENS测度进行加权。 3. 当所有物种被均等加权（即真实物种丰富度）时，完整模拟群落计算得到的ENS值随环境胁迫加剧持续降低；且随着加权程度提升，ENS与环境胁迫间的关联强度逐渐减弱，不同群落间的该关联差异也愈发显著。 4. 针对鱼类与蚌类群落计算得到的ENS，其在各样点间的变异程度……