Understanding the mechanisms behind biodiversity dynamics is central to assessing and forecasting anthropogenic impacts on ecological communities. However, the manner in which external environmental drivers act in concert with intrinsic ecological processes to influence local temporal turnover is currently largely unexplored. Here, we determine how human impacts affect multiple metrics of bird community turnover to establish the ecological mechanisms behind compositional change. We used US Breeding Bird Survey data to calculate transect‐level rates of three measures of temporal species turnover: (1) “short‐term” (initial rate of decline of Sørensen similarity), (2) “long‐term” (asymptotic Sørensen similarity), and (3) “throughput” (overall species accumulation rate from species–time relationship exponents) over 2692 transects across 27 regional habitat types. We then hierarchically fit linear models to estimate the effect of anthropogenic impact on these turnover metrics, using the Human Modification Index proxy, while accounting for observed species richness, the size of the species pool, and annual environmental variability. We found broadly consistent impacts of increased anthropogenic pressures across diverse habitat types. The Human Modification Index was associated with greater turnover at long timescales, but marginally slower short‐term turnover. The species “throughput” (accumulation rate) was not notably influenced. Examining anthropogenic impacts on different aspects of species turnover in combination allows greater ecological insight. Observed human impacts on short‐term turnover were the opposite of existing expectations and suggest humans are disrupting the background turnover of these systems, rather than simply driving rapid directed turnover. The increased long‐term turnover without concurrent increases in species accumulation implies human impacts lead to shifts in species occurrence frequency rather than simply greater arrival of “new” species. These results highlight the role of intrinsic dynamics and caution against simple interpretations of increased species turnover as reflections of environmental change.

中文翻译：

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群落变化较慢但更深：内在动力学调节人为对物种时间周转的影响


了解生物多样性动态背后的机制对于评估和预测人为对生态群落的影响至关重要。然而，外部环境驱动因素与内在生态过程协同作用以影响局部时间周转的方式目前在很大程度上尚未得到探索。在这里，我们确定了人类影响如何影响鸟类群落周转的多个指标，以建立成分变化背后的生态机制。我们使用美国繁殖鸟类调查数据来计算物种周转的三个时间指标的横断面水平率：（1） “短期”（Sørensen 相似性的初始下降率），（2） “长期”（渐近的 Sørensen 相似性）和 （3） “吞吐量”（来自物种-时间关系指数的总体物种积累率）超过 27 个区域栖息地类型的 2692 个样带。然后，我们使用人类改造指数代理分层拟合线性模型，以估计人为影响对这些周转指标的影响，同时考虑观察到的物种丰富度、物种库的大小和年度环境变异性。我们发现，人为压力增加对不同栖息地类型的影响大致一致。人类改造指数与长期尺度上的较高人员流动率相关，但短期人员流动率略慢。物种 “吞吐量” （积累率） 没有受到显著影响。结合研究人为因素对物种更替不同方面的影响，可以更深入地了解生态学。观察到的人为对短期周转率的影响与现有预期相反，这表明人为正在破坏这些系统的后台周转率，而不仅仅是推动快速的定向周转率。 长期周转的增加而物种积累没有同时增加，这意味着人类影响导致物种出现频率的变化，而不仅仅是“新”物种的更多到来。这些结果突出了内在动力学的作用，并警告不要简单地将物种更替增加解释为环境变化的反映。