Although dissolved organic nitrogen (DON) plays an important role in the dynamic processes of nitrogen mineralization, fixation and leaching, the ecological driving forces of DON across the Tibetan Plateau remain largely unknown. Here, we measured climate, soil, plant indicators and DON concentration on the Tibet Plateau, and used “Change-point” analysis to determine DON patterns. Then correlation analysis was applied to analyze the relationship between DON and each index. Finally, the structural equation model (SEM) is used to explain the overall effect between DON and environmental factors. Our results showed that two DON patterns were presented across the Tibetan Plateau, i.e., low-DON (5.43 g/mg) and high-DON (16.36 g/mg) patterns. In the Low-DON pattern, biologic factors such as microbial carbon, microbial nitrogen and productivity were the main influencing factors of DON concentration. In the high-DON pattern, DON was strongly governed by hydrothermal synchronization and superior soil environment. This study can help for us to have a more comprehensive understanding of the response mechanism of soil soluble nitrogen pool in alpine ecosystems under climate change.

中文翻译：

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生物和非生物因素分别调节青藏高原低营养浓度和高营养浓度的溶解有机氮

尽管溶解性有机氮（DON）在氮矿化、固定和浸出的动态过程中起着重要作用，但整个青藏高原 DON 的生态驱动力仍然很大程度上未知。在这里，我们测量了青藏高原的气候、土壤、植物指标和 DON 浓度，并使用“变化点”分析来确定 DON 模式。然后应用相关性分析来分析DON与各指标之间的关系。最后，使用结构方程模型（SEM）来解释 DON 与环境因素之间的整体影响。我们的研究结果表明，青藏高原有两种 DON 模式，即低 DON (5.43 g/mg) 和高 DON (16.36 g/mg) 模式。在 Low-DON 模式中，生物因素如微生物碳、微生物氮和生产力是DON浓度的主要影响因素。在高 DON 模式中，DON 受到热液同步和优越的土壤环境的强烈控制。本研究有助于我们更全面地了解气候变化下高寒生态系统土壤可溶性氮库的响应机制。