Worlds apart: location above- or belowground determines plant litter decomposition in a semiarid Patagonian steppe

1. While considerable attention has been devoted to how precipitation modulates net primary productivity in arid and semiarid ecosystems, the emergence of multi-faceted controls on carbon (C) turnover suggests that there is much to be understood with respect to the mechanistic controls on plant litter decomposition. 2. In the Patagonian steppe, we conducted a long-term factorial experiment, evaluating the importance of position, litter quality, tissue origin and soil resources on rates of C turnover under natural field conditions. Leaf and root litter of dominant grass species were placed in litterbags in different positions, on the soil surface and buried at 5 cm depth, with soil treatments of labile C, nitrogen (N) and their combination (C+N) over a three-year period.  3. As predicted, leaf litter decomposed significantly (nearly six-fold) faster aboveground than did root litter belowground (P &lt; 0.001). Surprisingly, root litter decomposed significantly faster than leaf lit...1. 尽管学界已针对降水如何调控干旱与半干旱生态系统的净初级生产力（net primary productivity）投入大量研究精力，但随着碳（C）周转多维度调控机制的逐步揭示，我们在植物枯落物分解（plant litter decomposition）的机制调控方面仍有诸多问题有待厘清。 2. 本研究在巴塔哥尼亚草原（Patagonian steppe）中开展了一项长期析因实验（factorial experiment），在自然野外条件下评估生境位置、枯落物质量、组织来源及土壤资源对碳周转速率的相对重要性。我们将优势禾本科植物的叶枯落物与根枯落物装入枯落物袋（litterbags），设置土壤表层、5cm土层深埋两种放置位置，并设置活性碳（labile C）、氮（nitrogen, N）以及二者联合处理（C+N）三种土壤调控组，实验周期长达三年。 3. 正如实验预期，叶枯落物在地上的分解速率显著（近6倍）快于地下的根枯落物（P < 0.001）。出乎意料的是，根枯落物的分解速率显著快于叶枯...