Anthropogenic nitrogen (N) inputs are causing large changes in ecosystems worldwide. Many previous studies have examined the impact of N on terrestrial ecosystems; however, most have added N at rates that are much higher than predicted future deposition rates. Here, we present the results from a gradient of experimental N addition (0–10 g·N·m⁻²) in a temperate grassland. After a decade of N addition, we found that all levels of N addition changed plant functional group composition, likely indicating altered function for plant communities exposed to 10 yr of N inputs. However, N addition only had weak impacts on species composition and this functional group shift was not driven by any particular species, suggesting high levels of functional redundancy among grasslands species. Adding other nutrients (P, K, and micronutrients) in combination with N caused substantially greater changes in the relative abundance of species and functional groups. Together, these results suggest that compositional change within functional groups may buffer grasslands from impacts of N deposition, but concurrent eutrophication with other elements will likely lead to substantial changes in plant composition and biomass.

中文翻译：

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社区变化可以缓冲慢性氮影响，但多种营养素会影响规模

人为氮 (N) 输入正在导致全球生态系统发生巨大变化。之前的许多研究都研究了 N 对陆地生态系统的影响；然而，大多数添加 N 的速率远高于预测的未来沉积速率。在这里，我们展示了实验 N 添加梯度 (0–10 g·N·m ^-2) 在温带草原。添加氮十年后，我们发现所有水平的氮添加都改变了植物功能群的组成，这可能表明暴露于 10 年氮输入的植物群落的功能发生了改变。然而，N添加对物种组成的影响很小，而且这种功能群的转变不受任何特定物种的驱动，表明草原物种之间存在高度的功能冗余。添加其他营养素（P、K 和微量营养素）与 N 相结合会导致物种和功能组的相对丰度发生更大的变化。总之，这些结果表明功能组内的组成变化可能会缓冲草原免受氮沉积的影响，