Nitrogen addition drives local extinction of legumes in meadow steppe

Nitrogen (N) enrichment poses a critical threat to legume diversity through three interlinked mechanisms: stimulating growth of non-leguminous competitors, enhancing community canopy coverage, and inducing light limitation. Canopy management practices such as mowing may partially mitigate these impacts by reducing species dominance and restoring light availability. Through a decadal field experiment in a meadow steppe, we systematically investigated the interactive effects of chronic N addition and mowing regimes on legume biomass dynamics and species persistence. Our findings demonstrate a time-dependent relationship between N enrichment and legume species richness. Most legume species, particularly rare and subordinate ones, were eliminated at intermediate-to-late stages when N addition rates exceeded 10 g N m−2 yr−1. This collapse correlated with the progressive suppression of legumes by biomass accumulation in the dominant non-legume species, Leymus chinensis. Beyond this ecological..., , , Description of the data and file structure The dataset is related to the paper \"Nitrogen Addition Drives Local Extinction of Legumes in Meadow Steppe\". The excel file contains four sheets. The “field experiment” (contains data from 2014-2023), “light transmittance” (2023) and “soil data” (2023) sheets contain data collected from the study site (field), and “greenhouse” sheet contains data collected in 2019 from the greenhouse of *Thermopsis lanceolata*. **Description:** *Variables* * plot: The nitrogen (N) treatment plot. The study site contains 480 plots, of which 384 are relevant to our study. * block: Study block. Each block contains 60 plots and total 8 blocks.  * type: N fertilizer types. This study includes (NH₄)₂SO₄, NH₄HCO₃, urea, slow-release urea. * dose: the N addition rates. Six rates are included, which are 0, 2, 5,10, 20 and 50 g N m⁻² yr⁻¹. *  mowing: The mowing treatment. * year: The study year. * ANPP: Aboveground net primary productivity in each plot (g m⁻² yr⁻¹)...,氮（Nitrogen，N）富集通过三种相互关联的作用机制对豆科植物多样性构成严重威胁：促进非豆科竞争植物的生长、提升群落冠层覆盖度，以及诱发光照限制。诸如刈割的冠层管理措施，可通过降低优势物种的竞争地位、恢复光照可及性，从而部分缓解上述负面影响。 本研究依托草甸草原的十年野外定位实验，系统探究了长期氮添加与刈割管理措施对豆科植物生物量动态及物种存续的交互影响。 研究结果显示，氮富集与豆科植物物种丰富度之间存在时间依赖性关系。当氮添加速率超过10 g N·m⁻²·yr⁻¹时，多数豆科物种（尤其是稀有种与从属种）在实验中晚期阶段会逐渐消亡。这一物种衰退过程与优势非豆科物种羊草（Leymus chinensis）通过生物量积累对豆科植物产生的渐进性抑制作用密切相关。[原文此处截断]……数据与文件结构说明 本数据集关联于题为《氮添加驱动草甸草原豆科植物局部灭绝》的研究论文。该Excel文件包含四个工作表：其中“野外实验”工作表涵盖2014-2023年的采集数据，“光照透射率”工作表与“土壤数据”工作表均包含2023年野外样地的实测数据，“温室实验”工作表则包含2019年在披针叶黄华（*Thermopsis lanceolata*）温室中获取的实验数据。 ### 变量说明 * **样地（plot）**：氮添加处理样地。本研究共设置480个样地，其中384个样地纳入本研究分析。 * **区组（block）**：研究区组。每个区组包含60个样地，共计8个区组。 * **氮肥类型（type）**：本研究使用的氮肥包括硫酸铵[(NH₄)₂SO₄]、碳酸氢铵(NH₄HCO₃)、尿素以及缓释尿素。 * **施氮剂量（dose）**：氮添加速率。共设置6个施氮梯度，分别为0、2、5、10、20和50 g N·m⁻²·yr⁻¹。 * **刈割处理（mowing）**：刈割管理措施。 * **年份（year）**：实验年份。 * **地上净初级生产力（ANPP）**：各样地的地上净初级生产力（单位：g·m⁻²·yr⁻¹）……