Modeling and sensor innovations in the last decade have enabled routine and continuous estimation of daily gross primary productivity (GPP) for rivers. Here, we generate and evaluate within and across year variability for 59 US rivers for which we have compiled a 14‐yr time series of daily GPP estimates. River productivity varied widely across (median annual GPP 462 g C m−2 yr−1, range 19–3445 g C m−2 yr−1) and within rivers (CVGPP‐Inter 5.7–37.3%). Within this dataset, we found that five rivers have become consistently more productive over time, while 11 rivers have become consistently less productive. Furthermore, trends in ecosystem phenology were identified, where cumulative annual GPP was reached earlier (n = 3) and later (n = 13) in the year across the 25th, 50th, 75th, and 95th percentiles. Understanding the drivers of productivity trends in rivers will elucidate patterns in river food webs and the functional role of river biogeochemistry.

中文翻译：

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河流总初级生产力物候表现出多年内的高度变异性，但跨年的稳定性


过去十年的建模和传感器创新使得对河流每日总初级生产力（GPP）的常规和连续估计成为可能。在这里，我们生成并评估了 59 条美国河流的年内和跨年变化，并为其编制了每日 GPP 估计值的 14 年时间序列。河流生产力差异很大（年平均 GPP 462 g C m −2年−1 ，范围 19–3445 g C m −2年−1 ）和河流内（CV GPP-Inter 5.7–37.3%）。在此数据集中，我们发现随着时间的推移，5 条河流的生产力持续提高，而 11 条河流的生产力持续下降。此外，还确定了生态系统物候趋势，其中累计年度 GPP 较早达到（ n = 3) 及之后 ( n = 13) 在这一年中 25 th , 50 th , 75 th 、95 th百分位数。了解河流生产力趋势的驱动因素将阐明河流食物网的模式和河流生物地球化学的功能作用。