Ongoing climate change is increasing rainfall variability in many parts of the world; in particular, the heaviest rainfall events are becoming heavier. In terrestrial ecosystems, nitrogen deposition is increasing as a result of emissions from fossil fuel burning and volatilization of nitrogen‐based fertilizers. These changes in the timing and rate of resource inputs can impact plant communities by altering competitive dynamics, succession, and community composition. In many systems, these are occurring alongside successional dynamics, making it difficult to tease apart mechanisms. Here, we resampled a nitrogen by rainfall variability manipulation experiment in a restored tallgrass prairie to examine the relative role of background community dynamics and treatment effects on plant diversity. During the treatment period, nitrogen addition and increased rainfall variability reduced diversity. Here, four and five years after the treatments were halted, we found similarly low levels of diversity across all treatments—an effect driven by dominance of a tall, fast‐growing, clonal forb, Solidago canadensis. The convergence of plots toward a low diversity state suggests that all experimental communities were gradually becoming dominated by S. canadensis, including in the absence of rainfall or nitrogen treatments. In contrast to short‐term findings from the same experiment, we conclude that our treatments accelerated succession toward a tall, clonal forb‐dominated community along an existing sere, but did not fundamentally alter longer‐term community composition—a result that was only apparent several years after the conclusion of the experiment. These findings reinforce the need to interpret the results from short‐term experimental manipulations within the context of long‐term successional change.

中文翻译：

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降雨变化性和氮素沉积的增加，加速了沿普通盆地的演替

持续的气候变化正在增加世界许多地方的降雨多变性；特别是，最大的降雨事件变得越来越严重。在陆地生态系统中，由于化石燃料燃烧和氮基肥料的挥发而产生的氮排放正在增加。资源投入时间和速率的这些变化会通过改变竞争动态，演替和社区组成来影响植物群落。在许多系统中，这些都是与连续动力学同时发生的，这使得很难区分机制。在这里，我们通过降雨变异性操作实验在恢复的高草草原上对氮进行了重新采样，以研究背景群落动态和处理对植物多样性的相对作用。在治疗期间 氮的添加和降雨多变性增加了多样性。在这种情况下，停止治疗四到五年后，我们发现所有治疗的多样性水平都较低，这是由高大，快速增长的无性系，加拿大一枝黄花。地块趋向低多样性状态表明，所有实验群落正逐渐被加拿大链球菌所控制，包括在没有降雨或不进行氮处理的情况下。与同一项实验的短期发现相反，我们得出的结论是，我们的治疗方法加速了沿现有Sere向一个高大的，克隆的，以Forb为主的社区的演替，但并未从根本上改变长期的社区组成，这一结果只是显而易见的实验结束几年后。这些发现加强了在长期连续变化的背景下解释短期实验操作的结果的需要。